Hyperalgesia and Medical Cannabis: What Research Shows
Short answer · 1 minute read
Hyperalgesia means something that normally hurts a little hurts far more than it should. It is a sign of an oversensitive pain system, not a disease of its own, and it can follow nerve damage, inflammation, a stroke or long-term opioid use. Cannabinoids have been studied for it almost only in animal and lab studies, so nobody can promise relief in people. Whether cannabis has a place in your pain plan is a question for a physician who sees your full medicine list, opioids above all.
On this page, results in rats, mice and lab dishes are labeled as such and kept apart from what is known in people. The full review starts at how strong the evidence is.
Why you can rely on this guide
- Every research figure carries a source you can open in the reference list.
- Each study is labeled: people, animals or cells in a dish.
- A study that found no benefit stays on the page and says so.
- Checked by physicians licensed in the states where we work. Meet them.
Pain that keeps getting louder: why hyperalgesia is so exhausting
A seam in a shirt. The spray of a shower. A friend’s handshake that lasts a second too long. With hyperalgesia, small things that should barely register can set off pain that lingers, and the people around you see nothing wrong. Many patients hear “it can’t hurt that much” long before anyone puts a name to it.
It wears you down in loops. Pain breaks your sleep, and a short night makes the next day hurt more. On opioids, the dose goes up and the pain goes up with it. None of this is in your head: it is the pain system turning up its own volume.
Small things set it off
A pinch, a bump or warm water that should sting for a moment hurts hard and keeps hurting. The area that is sore can slowly widen.
More medicine, more pain
When pain spreads and worsens while the opioid dose rises, doctors consider opioid-induced hyperalgesia rather than simple tolerance.
Pain and poor sleep feed each other
Broken nights leave the nervous system on edge. One mouse study traced that link to the brain’s own cannabinoids.
Where does your pain sensitivity start? Find your path
Pick the situation closest to yours, and the guide points you to the parts that answer it.
You have taken opioids for months and the pain is getting worse
Rising pain on a rising dose can be tolerance, withdrawal between doses or opioid-induced hyperalgesia. Telling them apart is your prescriber’s job, and no change to the opioid should happen without them.
Opioid-induced hyperalgesia · What is known about cannabis here · Interactions
The pain began after shingles, a stroke or an injury to a nerve
Damaged nerves and a changed spinal cord or brain can keep pain turned up long after the first injury healed. These are some of the best-known causes of hyperalgesia.
Your scalp turns tender during headaches
Brushing hair or resting your head on a pillow can hurt during a migraine attack. That tenderness shows how sensitized the pain system has become.
You live with cancer or have had chemotherapy
Tumors, surgery, radiation and some chemotherapy drugs can sensitize nerves, and many patients also take opioids. The interaction section matters most here.
Your state does not list hyperalgesia
No state program names hyperalgesia on its own. The condition behind it, such as chronic pain, cancer or migraine, is what a licensed physician checks against your state’s current list.
What is hyperalgesia? Definition, meaning and pronunciation
Hyperalgesia is an increased pain response to something that is normally painful: a pinprick, a pinch, a hot surface. The stimulus is the usual one. The pain is bigger, often longer, and sometimes spreads beyond the spot that was touched. The International Association for the Study of Pain defines it as “increased pain from a stimulus that normally provokes pain” [1].
In simple words: your alarm system still rings for the right things, only far too loudly. It is a sign, the way a fever is a sign, and doctors look for what is driving it.
Pronounced hy-per-al-JEE-zee-uh. British and Australian texts spell it hyperalgaesia. From Greek hyper (over) and algesis (sense of pain) [2].
Primary and secondary hyperalgesia
Primary hyperalgesia
Where it hurts
Right at the injured or inflamed spot: the burn, the cut, the swollen joint.
Why
Nerve endings in damaged tissue become easier to fire. Doctors call this peripheral sensitization.
Secondary hyperalgesia
Where it hurts
In the healthy skin around the injury, often in a widening ring.
Why
The spinal cord and brain amplify incoming signals. Doctors call this central sensitization.
What “hyperalgesia syndrome” means
There is no single disease called hyperalgesia syndrome. People use the phrase for a lasting pattern of oversensitive pain, most often opioid-induced hyperalgesia or the widespread sensitivity seen with conditions such as fibromyalgia. A doctor names the condition behind the pattern.
How the same touch can hurt differently
How to read it: choose a stimulus, and the three rows show how much it tends to hurt with a typical nervous system, with hyperalgesia and with allodynia. This is a schematic built from the IASP definitions, not measured data [1].
From something that never hurts to something that hurts anyone. Think of what set off your pain today and find the closest step.
A typical nervous system
–
With hyperalgesia
–
With allodynia
–
Show as a table
| Stimulus | Typical | With hyperalgesia | With allodynia |
|---|---|---|---|
| Feather touch | No pain | No pain | Moderate pain |
| Warm water | No pain | No pain | Moderate pain |
| Firm press | Mild | Moderate | Strong |
| Pinprick | Mild | Strong | Not the right term: it is meant to hurt |
| Hot pan | Strong | Severe | Not the right term: it is meant to hurt |
Quick answers
Is hyperalgesia a symptom or a condition?
A symptom, or more exactly a sign that the pain system is sensitized. Doctors treat it by finding and treating what lies behind it, such as nerve damage, inflammation or long-term opioid use.
Hyperalgesia is seen in which conditions?
Most often in neuropathic pain, shingles and postherpetic neuralgia, pain after a stroke, cancer and its treatment, migraine, fibromyalgia, inflamed or injured tissue and long-term opioid use. Each is explained in what causes hyperalgesia.
Is pain from a light touch hyperalgesia?
Strictly, no. Pain from something that should not hurt at all, like a feather or clothing, is called allodynia [1]. The two often appear together, which is why they are mixed up. See the comparison.
Is there an ICD-10 code for hyperalgesia?
Not one that names it. The visit is coded under the condition behind it, explained in how doctors diagnose hyperalgesia.
Hyperalgesia vs allodynia vs hyperesthesia: what’s the difference?
Hyperalgesia is more pain from something painful; allodynia is pain from something that should not hurt at all [1]. Hyperesthesia is the wider word for any heightened sensitivity to touch, warmth or cold, painful or not. Hyperpathia and dysesthesia complete the family that doctors use to describe how a sensitized system behaves.
A guide for the conversation with a doctor, not a way to diagnose yourself.
Compare hyperalgesia with:
| What to look at | Hyperalgesia | Allodynia | Hyperesthesia | Hyperpathia | Dysesthesia |
|---|---|---|---|---|---|
| What sets it off | Something that normally hurts a little | Something that should not hurt at all | Any touch, warmth or cold | A repeated or stronger stimulus | Touch, or nothing at all |
| What the person feels | Pain that is bigger and lasts longer than expected | Real pain from something harmless | Everything feels too strong, painful or not | Explosive, building pain that outlasts the trigger | An unpleasant, odd sensation such as burning or crawling |
| Everyday example | A flu shot that aches for days | A bedsheet on the skin hurts | A tag in a shirt feels unbearable | Light taps that suddenly flare into severe pain | Burning feet at night with nothing touching them |
| Often seen with | Inflammation, nerve damage, long-term opioids | Migraine, shingles, fibromyalgia | Nerve injury, skin conditions | Nerve damage with numb areas | Diabetic neuropathy, multiple sclerosis |
Hyperalgesia and allodynia: why they are named together
Both come from the same sensitized system, and one person can have both at once: the sunburned back that hurts under warm water (allodynia) and burns far too much when slapped (hyperalgesia). Searching “hyperalgesia to touch” usually describes allodynia. Doctors test them separately, with a soft brush for allodynia and a pin or pressure for hyperalgesia.
Hyperesthesia is the wider term
Hyperesthesia covers any increase in sensitivity, including touch that feels too intense without hurting. Hyperalgesia and allodynia are both kinds of it. Hyperalgesia of the skin, the skin hurting too much when pricked or warmed, sits where the two words overlap.
Hyperalgesia symptoms: skin, touch, heat and headache
The core symptom is pain out of proportion to its cause. A doctor will want to know which kind of stimulus sets it off, how far the sore area reaches and how long the pain lasts afterward. Hyperalgesia can be mechanical (pressure, pinprick), thermal (heat or cold) or both, and the pattern points toward the cause.
Which of these do you notice?
Tap “I notice this” on the right for each change that matches yours. Nothing is saved or sent.
Touch and pressure
What most people feel
A firm squeeze or a bump stings for a moment, then fades.
What sensitized pain feels like
The same squeeze brings sharp pain that throbs for minutes.
Heat
What most people feel
Hot tap water is uncomfortable, and you pull your hand away.
What sensitized pain feels like
Warmth that others find pleasant burns, and the burning stays.
Cold
What most people feel
An ice cube feels cold and a little sharp.
What sensitized pain feels like
A cold drink or a draft brings aching or stabbing pain.
Pinprick
What most people feel
A blood test or a splinter hurts briefly.
What sensitized pain feels like
A small prick feels like a deep cut, and the skin around it aches.
Scalp during a headache
What most people feel
Brushing your hair feels the same as on any other day.
What sensitized pain feels like
During an attack, a ponytail, glasses or a pillow make the scalp hurt.
Spread and after-pain
What most people feel
Pain stays where you were hurt and settles as it heals.
What sensitized pain feels like
The sore area widens over weeks and keeps hurting after the trigger is gone.
Hyperalgesia headache and a tender scalp
During migraine attacks many people find their scalp, face or neck sore to touch, a sign that pain pathways in the brainstem have become sensitized. Tenderness that comes with every attack and lingers between them is worth describing to your doctor, because it can change which preventive treatment makes sense. More on migraine and medical cannabis and headache.
When to get help right away
- Sudden numbness or weakness of the face, an arm or a leg, especially on one side, trouble speaking or a drooping face: call 911, these are stroke signs [3].
- New burning pain with a rash in a band on one side of the body, which may be shingles; early treatment matters [4].
- Pain that spreads quickly with fever, red or hot skin.
- Pain rising on opioids together with deep sleepiness or slow breathing.
What causes hyperalgesia? Conditions it is seen in
Hyperalgesia is caused by sensitization: nerves, the spinal cord or the brain turning up the volume on pain signals after injury, inflammation, nerve damage or long-term opioid use [5]. Most people with it have one of the conditions below.
Peripheral and central sensitization, in plain words
Peripheral sensitization happens at the site. Inflamed or injured tissue releases chemicals that make nearby nerve endings fire more easily, so a light pinch reads as a strong one. This is why a sprained ankle is so tender.
Central sensitization happens higher up. After strong or lasting pain, nerve cells in the spinal cord and brain start amplifying every signal they receive and keep doing so after the injury heals. In animal studies, the body’s own cannabinoids take part in this amplification and in damping it, which is why researchers study them; see the endocannabinoid system.
Shingles and postherpetic neuralgia
The shingles virus damages nerves in a band of skin. Pain that stays after the rash heals is called postherpetic neuralgia, and the skin often hurts to touch and pressure [4].
Pain after a stroke
A stroke in the pain pathways of the brain can leave one side of the body oversensitive to touch, heat or cold, sometimes months later. See brain ischemia.
Nerve damage and neuropathy
Diabetes, injury, surgery and some infections damage nerves, which then misfire and overreact [6].
Cancer and cancer treatment
Tumors press on nerves, and surgery, radiation and some chemotherapy drugs can injure them [7]. See cancer and medical cannabis.
Headache and migraine
Repeated attacks sensitize pain pathways in the head, which is why the scalp turns tender. See migraine.
Long-lasting pain and fibromyalgia
Months of pain from arthritis, the back or fibromyalgia can turn central sensitization into the main problem. See chronic pain.
Sleep loss and stress
In rats and mice, broken sleep and chronic stress made animals more sensitive to pain [8][9]. See the sleep study and insomnia.
Long-term opioids
Opioids can themselves sensitize the pain system, so pain grows as the dose grows [10]. See opioid-induced hyperalgesia.
No causes match this filter.
Opioid-induced hyperalgesia: when pain medicine makes pain worse
In short: opioids can make the pain system more sensitive, so pain grows and spreads even as the dose rises. The FDA added this warning to every opioid pain medicine label in 2023 [10].
Opioid-induced hyperalgesia (OIH) is increased sensitivity to pain caused by opioids themselves. It differs from tolerance, where the same dose simply works less well. With OIH, pain may become more widespread, change its character and appear in places that did not hurt before, and raising the dose makes it worse rather than better [10].
Tolerance, OIH or withdrawal?
Three patterns that look alike from the inside. Choose one to see how clinicians tell it apart.
Tolerance
When the dose goes up
Pain eases again, at least for a while.
Where it hurts
The same place as the original problem.
What clinicians look at
Whether the underlying condition has changed and whether the plan still fits.
Opioid-induced hyperalgesia
When the dose goes up
Pain gets worse, not better.
Where it hurts
More widely, often in new places, with touch or warmth starting to hurt.
What clinicians look at
A careful dose reduction or a different plan, never on your own [10].
Withdrawal
When the dose goes up
Pain and other symptoms settle.
Where it hurts
Aches, sweating, restlessness and gut upset as a dose wears off or after a cut.
What clinicians look at
Timing against doses, and a slower taper [11].
Can long-term opioid use cause hyperalgesia?
Yes. It can follow months of daily use, higher doses, or quick dose increases, though it can appear at other times too [10]. It is one reason guidelines ask prescribers to review long-term opioid plans regularly with the patient [11].
Remifentanil and pain after surgery
Remifentanil, a very short-acting opioid given during anesthesia, has been linked with stronger pain after surgery. In a rat model of this effect, a lab-made cannabinoid injected into the spinal canal reduced the extra pain by calming support cells in the spinal cord [12]. That is an animal result and not a treatment.
Can tramadol cause hyperalgesia?
Tramadol is an opioid pain medicine, and the opioid-induced hyperalgesia warning applies to its label as it does to the others [10]. If tramadol seems to work less and less while pain spreads, tell the prescriber rather than taking extra doses.
Can OIH be reversed? Ketamine and other options
Often it improves once the opioid plan changes. What that change looks like is an individual clinical decision: a slow reduction, a different medicine, or adding a non-opioid approach. Ketamine, an NMDA receptor blocker given under medical supervision, is one of the options studied for OIH. There is no single “best opioid” for it.
What is known about cannabis and OIH · Opioids and cannabis together
How doctors diagnose hyperalgesia: exam, testing and ICD-10 codes
There is no blood test or scan for hyperalgesia. It is found at the bedside, by comparing how a sore area and a healthy area respond to the same gentle tests, and by a careful history of medicines.
- A history: when the pain began, what sets it off, and every medicine with its dose, opioids especially.
- A pain map: you or the doctor shade where it hurts, so changes over time can be compared.
- Bedside tests: a soft brush (for allodynia), a pin or a pressure device, and something warm and cold, each on the sore and the healthy side.
- Quantitative sensory testing (QST) in some clinics: measured heat, cold and pressure to find the exact point where each starts to hurt.
- Ruling out look-alikes: new nerve damage, a progressing disease, an infection or withdrawal between doses.
Hyperalgesia ICD-10 code: is there one?
ICD-10-CM, the coding system used in the United States, has no code titled “hyperalgesia” [13]. Clinicians code the condition behind it, or a group such as disturbances of skin sensation (R20) or pain not elsewhere classified (G89). The exact code depends on the clinical picture and is chosen by the clinician.
What gets coded instead?
The underlying diagnosis: postherpetic neuralgia, a neuropathy, central pain after a stroke, chronic pain, a cancer, or an adverse effect of an opioid. That diagnosis, not the word hyperalgesia, is also what a medical cannabis program looks at; see qualifying conditions.
What should I bring to the appointment?
Two weeks of a pain diary, your medicine list with doses and any visit notes that name a diagnosis. The checklist is in how to talk to your doctor.
Does my pain sound like hyperalgesia, and is cannabis worth raising with a physician?
Thirteen short questions about how your pain behaves, the medicines you take and your health. Your answers stay on this page and show what to bring to a physician.
13 questions · about a minute · your answers stay in this browser
How to treat hyperalgesia: standard options and does it go away
Treatment depends on the cause: treating the condition behind it, reviewing medicines such as opioids, and pain-focused therapies chosen with a clinician. For nerve-related pain, UK guidance (NICE CKS) starts with amitriptyline, duloxetine, gabapentin or pregabalin, and keeps capsaicin cream for small areas [14]. US clinicians use similar first steps.
Treating what drives it
Controlling blood sugar in diabetic neuropathy, treating shingles early, managing inflammation or a cancer. When the cause settles, sensitization often settles too.
An opioid review
If opioid-induced hyperalgesia is suspected, the prescriber may lower the dose slowly or change the plan [10][11].
Gabapentin and pregabalin
Nerve-calming medicines used first for neuropathic pain [14]. They cause drowsiness and dizziness.
Duloxetine and amitriptyline
An SNRI and a tricyclic antidepressant used at pain doses, which strengthen the body’s own pain-damping pathways [14].
Lidocaine and capsaicin
Numbing patches and creams, and high-strength capsaicin, act on a small sore area with little effect on the rest of the body [14].
NMDA blockers such as ketamine
Used in specialist care, for example around surgery or for opioid-induced hyperalgesia, under monitoring.
Physical therapy
Graded movement and gentle desensitization, touching the sore area with softer then firmer textures, retrain an overreacting system.
CBT and pain education
Cognitive behavioral therapy changes how the brain weighs pain signals and helps with the fear of moving.
Sleep
Regular hours, treating sleep apnea or insomnia, and less screen time at night. Better sleep is one of the few levers you hold yourself.
No treatments match this filter.
Is medical cannabis worth raising with a physician for hyperalgesia?
For some people, yes, as a question rather than a plan. The conversation is about your symptoms and the condition behind them, not a treatment for hyperalgesia itself, because no such treatment has been tested in people. A physician weighs the diagnosis in your records, what you have already tried, every medicine you take and the risks that apply to you. Then they say whether a recommendation fits, or why it does not.
A conversation makes sense if
- Standard treatment has not settled the pain, or its side effects are hard to live with.
- The condition behind it is diagnosed and written in your records.
- You can bring a complete medicine list, opioids included.
- You want an honest view of the evidence, not a promise.
It is not the right step if
- The hope is to replace or cut an opioid on your own.
- New numbness, weakness or a rash has not been checked yet.
- You are pregnant or have had psychosis.
- You need to drive or work with machinery right after a dose.
The evaluation is a one-on-one appointment with a physician licensed in your state, who reviews your history and medicines. The fee for your state is shown before you pay.
Why cannabis comes up in pain sensitization: the endocannabinoid system
Your body makes its own cannabinoid-like messengers, called endocannabinoids, and the receptors they act on sit along the whole pain pathway: in nerve endings, the spinal cord and the brain areas that turn pain up or down. In animal studies this system takes part in both directions. It can damp an overreacting pain signal, and in some settings it helps a touch pathway become painful [15][16].
That double role is why cannabis is discussed for hyperalgesia and why the answer is not simple. Everything in this section comes from experiments on animals or cells, not from patients.
The parts of the system, one card each
Anandamide
animal studies
One of the body’s own cannabinoids. Given locally in rats it eased pain at the paw [17], and mice whose pain nerves kept more of it had less inflammatory pain [18].
2-AG
animal studies
The most plentiful endocannabinoid. In rats it helped inflammatory pain resolve [19]; in leech nerve cells it helped touch synapses turn painful [16].
NADA
animal studies
N-arachidonoyl dopamine, a lesser-known endocannabinoid. In mice, broken sleep lowered it in the thalamus, and pain sensitivity rose [8].
THC
animal studies
The main intoxicating compound of cannabis, acting on CB1. In an animal model of eye pain, a small amount of delta-8-THC combined with a CB1 booster eased pain from capsaicin [20].
CBD
animal studies
A non-intoxicating cannabinoid. In rats with acute inflammation it reduced hyperalgesia through TRPV1 rather than through CB1 or CB2 [21].
CB1 receptor
animal studies
Found on nerve cells. In mice, spinal CB1 receptors carried pain sensitization from strong nerve-fiber activity [15]; in rats they took part in morphine-induced hyperalgesia [22].
CB2 receptor
animal studies
Mostly on immune and support cells. A drug acting on CB2, injected into the spinal canal of rats, reduced hyperalgesia after remifentanil [12].
TRPV1
animal studies
The heat and capsaicin sensor on pain nerves, the same one chili peppers trigger. Several cannabinoids act on it, CBD among them [21][23].
FABP5 and FAAH
animal studies
A carrier and an enzyme that clear anandamide away. Removing FABP5 in mouse pain nerves calmed TRPV1 [18]; FAAH rose in a pain-control area of rats with nerve injury [24].
THC and CBD act on different targets. A result for one does not carry over to the other, and none of these results tells you how a product from a dispensary would act in you.
The sleep and pain study · More on the endocannabinoid system
Sleep loss, pain and the brain’s own cannabinoids: a mouse study
Anyone who has slept badly for a week knows that everything hurts more. A 2023 study in mice looked for the reason inside the brain, and found it in an endocannabinoid [8].
-
In mice
Sleep was broken night after night
The animals were repeatedly woken over several days, a model of chronic sleep disruption.
-
In mice
NADA and CB1 activity fell in the thalamus
The thalamic reticular nucleus, a gatekeeper for incoming signals, had less NADA and weaker CB1 signaling.
-
In mice
More pain signals got through
With the gatekeeper quieter, the part of the thalamus that relays pain grew overactive, and the mice became hyperalgesic. Restoring NADA there reversed it [8].
What was shown in mice
A clear chain from broken sleep to an endocannabinoid in one brain area to stronger pain. The substances were placed directly into the brain, a method that has no counterpart in medical use.
What it means for people
This study did not test people or any cannabis product, so it says nothing about whether cannabis would help your sleep or your pain. What it does support is a practical step: tell your physician how you sleep, because sleep belongs in any pain plan. Read whether cannabis is good or bad for sleep.
How strong is the evidence? What research shows, from strongest to weakest
In short: almost all of it comes from animals and lab dishes. No trial has tested cannabis for hyperalgesia in people, so these results cannot be applied to patients.
A randomized trial, where people are assigned by chance to a treatment or a placebo, can show whether something helps. A study that observes people can show a link. An animal experiment can show a mechanism. Here is what exists for hyperalgesia on each rung.
| Level | What exists for hyperalgesia | What it can and cannot tell you |
|---|---|---|
| Trials in people | None that test cannabis or cannabinoids for hyperalgesia. One mouse experiment on FABP5 carries a trial label in research databases [18]. | This is the rung that would show benefit and side effects in patients. It is empty. |
| Studies in people | An experimental pain model in volunteers alongside mouse work on spinal sensitization [15]. | Shows that the mechanism exists in humans, not that a product helps. |
| Animal and lab work | Rats, mice and leeches given cannabinoids by injection into a paw, the spine or the brain [8][19][12]. | Explains why scientists are interested. Says nothing about doses or forms for people. |
What kinds of studies is this evidence built on?
How to read it: one row per type of study on cannabinoids and hyperalgesia; a longer bar means more studies. Stronger designs come first. Gray bars are animal and lab work, useful for ideas, unable to show whether patients benefit. The two studies labeled as trials include the FABP5 work, which was done in mice [18].
Show as a table
| Design | Studies |
|---|---|
| Narrative review | 1 |
| Labeled as clinical trials | 2 |
| Cell and lab studies | 3 |
| Animal studies | 72 |
| Decade | Studies |
|---|---|
| 2000s | 2 |
| 2010s | 10 |
| 2020s | 6 |
Browse the studies yourself
Each card is one paper this guide cites, summed up in a sentence or two. Papers that found no added benefit, or that test something other than a cannabis product, stay in the list and carry a label.
Stress hormones, 2-AG and pain that resolves
During paw inflammation, natural stress hormones raised 2-AG in a pain-control area of the brain and helped pain resolve; constant stimulation made CB1 receptors less responsive [19].
Broken sleep and NADA in the thalamus
Chronic sleep disruption lowered NADA and CB1 activity in the thalamic reticular nucleus, and the mice grew more sensitive to pain [8].
How touch pathways turn painful
Strong activity in pain fibers strengthened nearby touch synapses through endocannabinoids and NMDA receptors, a simple model of touch becoming painful [16].
Removing FABP5 from pain nerves
More anandamide in pain nerves calmed TRPV1 and reduced inflammatory pain in genetically altered mice [18].
Gene changes behind opioid-induced hyperalgesia
Mice given repeated morphine showed widespread changes in how genes are spliced in a pain nerve hub and a reward area of the brain [25].
Delta-8-THC and eye pain
Eye drops with CB1-boosting compounds, alone or with a small amount of delta-8-THC, eased pain and inflammation of the cornea; a CB1 blocker removed the effect [20].
Electroacupuncture and morphine hyperalgesia
Electroacupuncture eased morphine-induced hyperalgesia through spinal CB1 receptors; a CB1 agonist added to it and a CB1 blocker weakened it [22].
An antipsychotic that works through cannabinoids
The pain-relieving effect of aripiprazole at the paw depended partly on the endocannabinoid system [26].
Cannabinoid plus opioid at the paw
Given together into an inflamed paw, a CB1 agonist and an opioid agonist worked against each other rather than adding up [27].
Olvanil and heat hyperalgesia
A non-burning cousin of capsaicin reduced heat hyperalgesia and desensitized TRPV1 [23].
Chronic stress and two kinds of pain
Repeated stress made some body regions more sensitive than others, with different endocannabinoid changes in each [9].
A CB2 drug after remifentanil
JWH015, injected into the spinal canal, reduced remifentanil-induced pain after surgery by calming spinal support cells [12].
Local cannabinoids and the noradrenaline system
Anandamide and PEA given at the paw eased pain by switching on the body’s noradrenaline pathway [17].
Common painkillers and cannabinoid receptors
Tested whether cannabinoid receptors take part in how dipyrone, diclofenac and other NSAIDs ease pain at the paw; the answer differed by drug [28].
Inflammation and spinal fat messengers
Paw inflammation set off production of signaling lipids in the spinal cord that sustain touch hyperalgesia [29].
Spinal endocannabinoids and sensitization
Intense pain-fiber activity released endocannabinoids in the spinal cord, and CB1 receptors there helped spread sensitivity to nearby touch [15].
FAAH after nerve injury
Three weeks after a nerve injury, the anandamide-clearing enzyme FAAH rose in a brain pain-control area, alongside a slower heart rate [24].
CBD and acute inflammation
CBD reduced hyperalgesia in acute paw inflammation, and its effect ran through TRPV1 rather than CB1 or CB2 [21].
No studies of this type are cited here.
Cannabis and opioid-induced hyperalgesia: what’s known so far
Nothing has been shown in people. No study has tested whether cannabis or a cannabinoid helps opioid-induced hyperalgesia in patients. What exists are four animal experiments, and one of them found the opposite of what people might hope.
| Study | Model | What was tested | Finding (in animals) |
|---|---|---|---|
| 2021 [25] | Mice on repeated morphine | Gene changes behind OIH | Widespread splicing changes in pain and reward areas; not a cannabinoid test |
| 2019 [22] | Rats with morphine hyperalgesia | Electroacupuncture and spinal CB1 | Relief depended on CB1 receptors in the spinal cord |
| 2014 [12] | Rats after remifentanil and surgery | A CB2 drug injected into the spinal canal | Less extra pain, through calmer spinal support cells |
| 2016 [27] | Rats with an inflamed paw | A CB1 agonist together with an opioid agonist | The two worked against each other, not together |
Look at how the substances reached the animals: injected into a paw or into the fluid around the spinal cord. That has nothing in common with a gummy, an oil under the tongue or a vape, and none of these results transfers to them.
What science doesn’t know yet
Here the unknowns outweigh the knowns. The authors of these studies name the same limits again and again, and they are worth knowing before anyone decides anything.
- Almost every result comes from rats and mice, and the study authors themselves note that several experiments used only male animals.
- One line of work rests on leeches, whose nerve cells may not behave like a person’s [16].
- Most models are short bursts of inflammation, not the months or years of pain people live with.
- There is no randomized trial of cannabis for hyperalgesia in people, so no dose, form or THC to CBD ratio has been tested.
- Nobody knows whether these effects carry over to opioid-induced hyperalgesia or to central pain after a stroke in patients.
- Substances were injected into paws, the spine or the brain; how swallowed or inhaled cannabinoids would act was not studied.
- Some promising findings involve the body’s own cannabinoids, not anything a dispensary sells [19][18].
How to read a headline about cannabis and pain
News stories rarely say which kind of study they describe. Five questions sort most of them in a minute.
- Who was studied? Mice, cells or people. A result in animals is a reason to run a trial, not to change care.
- How was it given? An injection into a rat’s paw is not a product you can buy.
- Was there a comparison group? Pain changes when people expect it to. Without a placebo, a gain may be expectation.
- Which product and how much? THC, CBD and lab-made compounds act differently.
- What was measured? A paw withdrawn a little later is not the same as a better week.
If an article cannot answer most of these, treat it as a question for your appointment rather than an answer.
Forms of cannabis: what each form avoids and what stays
Medical cannabis is smoked and vaped, but it is also eaten, swallowed as capsules, dropped under the tongue, rubbed on skin and worn as a patch. The studies on this page used injections in animals, so they say nothing about any of these forms. What can be said is what each form avoids and what it keeps. None of this recommends a form: that choice is made with a physician.
Which form are you asking about?
The card that applies to every form stays in view; choosing a form adds what is specific to it.
Smoking: joints, blunts, pipes, bongs
Burning plant matter sends smoke into the lungs and airways. The THC in each puff cannot be read off a label, and effects start within minutes.
Vaping and dabbing
Dry-herb vaporizers, oil pens and cartridges heat rather than burn, yet warm aerosol still reaches the airways. Wax, shatter and rosin used for dabbing are very strong, so a small slip becomes a large dose.
Shared devices
A joint, pipe or vape passed between people passes on colds and other infections too.
Edibles, drinks and capsules
No smoke and no aerosol. They take an hour or more to act and last for hours, and the liver works on them first. A second helping “because nothing happened” is a common route to taking too much.
Tinctures, oils and mouth sprays
Held under the tongue or sprayed inside the cheek, they avoid the lungs and are counted in drops or sprays. Part of each dose is still swallowed and goes through the liver.
Creams, balms and patches
Creams and balms act mainly where they are rubbed in, which is why people with skin that hurts to touch ask about them; no study on this page tested them. Transdermal patches are different: they release cannabinoids into the blood, so drowsiness and interactions apply as with anything swallowed.
Suppositories
Rarely used. They bypass the stomach and lungs, but what reaches the blood still acts on the brain and on other medicines.
Prescription medicines: dronabinol, nabilone, Epidiolex
Dronabinol (Marinol, Syndros), nabilone (Cesamet) and cannabidiol (Epidiolex) are FDA-approved medicines with an exact dose, prescribed by a doctor and filled at a pharmacy [30]. They are not bought with a medical card, and none is approved for hyperalgesia.
True of every form
- THC in any form can bring drowsiness, dizziness and slower thinking, and it stacks with opioids, gabapentinoids and sleeping pills.
- CBD and THC pass through liver enzymes shared with many prescriptions, so levels of those medicines can shift [31].
- A risk of THC does not transfer to a CBD-only product, nor the other way round.
- No driving after use [32].
All forms as a table
| Form | What it avoids | What it keeps |
|---|---|---|
| Smoking | A delayed onset | Smoke in the airways, shared devices, an unmeasured dose, every effect of THC |
| Vaping and dabbing | Burning plant matter | Warm aerosol in the airways, very strong concentrates, shared devices, every effect of THC |
| Edibles and capsules | Smoke, aerosol, shared devices | Slow onset, long effect, the second-helping trap, liver processing, interactions |
| Tinctures and sprays | Smoke, aerosol, shared devices | Effects on the brain, part of the dose swallowed, interactions |
| Creams and balms | Most effects on the brain | Skin reactions; untested for hyperalgesia |
| Transdermal patches | Smoke, aerosol, swallowing | Effects on the brain, interactions, drowsiness |
| Suppositories | Swallowing, airways | Effects on the brain, interactions |
| Prescription medicines | Unknown product content | Drowsiness, dizziness, interactions; not approved for hyperalgesia |
Is cannabis safe with hyperalgesia? Side effects and who should not use it
The studies on this page measured pain in animals; none recorded side effects in people with hyperalgesia, so there are no figures to give here. What is known about THC in general comes from public health agencies, and it matters most for people who already take sedating pain medicines [33][34].
Drowsiness
THC can make you sleepy, and opioids, gabapentin, pregabalin and sleeping pills add to it.
Dizziness
Light-headedness and a drop in blood pressure on standing, worst when getting up at night.
Slower thinking
Memory, attention and reaction time slip while THC acts [34].
Anxiety or paranoia
Higher THC doses can bring a racing heart, worry or suspicion, especially in people new to it [33].
Falls
Sleepiness and unsteadiness add up, and older adults on several medicines are most at risk.
Driving
Cannabis slows reactions and impairs driving; driving after use is illegal in every state [32].
Two habits lower the risk whatever is decided: keep one written list of every medicine and product with its dose, and never take more because a swallowed product “hasn’t kicked in yet.”
Who should not use cannabis for pain sensitivity
For some people the honest answer is “not now” or “not at all,” however strong the pain. Trials in this field usually leave these groups out, so there is no evidence that cannabis is safe for them.
Which of these apply to you?
Tap everything that applies, and only the matching notes stay below. Nothing is saved or sent.
Pregnancy or breastfeeding. THC reaches the baby through the placenta and breast milk, and no amount is known to be safe [34].
A history of psychosis. THC can bring back or worsen hallucinations and delusions [33]. See cannabis and psychosis.
Serious heart disease. THC can speed the heart and change blood pressure, so a physician weighs any new drug with care.
Teenagers and young adults. The developing brain is more sensitive to THC, and most programs set extra rules for minors [34].
Several sedating medicines. Opioids, benzodiazepines, gabapentinoids and sleeping pills already slow breathing and thinking; adding THC deepens that.
Recent falls. Dizziness and drowsiness raise the risk of the next fall, and a broken hip outweighs any expected benefit.
“Not now” and “not at all” are different answers. A recent fall or a medicine change in progress can push the conversation back a few weeks. A history of psychosis may close it. The physician should say which applies and why.
Drug interactions: opioids, gabapentinoids, antidepressants
For people with hyperalgesia, the medicine list often matters more than the diagnosis. Below is what is known, marked by the kind of source behind it. It is not a full list, and the physician checks each medicine by name.
What is on your medicine list?
Take the pharmacy printout or the bottle labels and tap everything you take; the matching entries open below.
Opioids, benzodiazepines and sleeping pills clinical source
Each of these slows the brain, and with THC the effects add up: deeper drowsiness, slower reactions and, with opioids, a risk of slowed breathing [10][33]. Opioid labels warn against combining them with other sedating substances [10]. See mixing cannabis and Xanax.
Gabapentin and pregabalin clinical source
Both cause drowsiness and dizziness on their own [14]. Added to THC, the sleepiness and unsteadiness can stack, which matters for driving and falls.
CBD, liver enzymes and many prescriptions clinical source
CBD blocks liver enzymes of the CYP450 family that clear many medicines, including some antidepressants, seizure drugs and blood thinners, so their levels can rise [31]. Duloxetine and amitriptyline are cleared this way. With five or more prescriptions, a pharmacist review before any change is worth asking for.
Steroids (glucocorticoids) animal data
In rats, the body’s own steroid hormones raised 2-AG in a pain-control area, and too much stimulation made CB1 receptors less responsive [19]. What this means for a person taking prednisone and cannabis is unknown.
Ibuprofen, diclofenac and other NSAIDs animal data
In animals, cannabinoid receptors took part in the pain relief of some NSAIDs at the paw [28]. No patient data. Read mixing cannabis and ibuprofen.
Opioids and cannabinoids at the same site animal data
No entries match this filter.
Questions to ask about the medicine list
- Which of my medicines already make me drowsy or unsteady, and would anything new add to that?
- Are any of them cleared by the same liver enzymes as CBD or THC?
- Should anything be reduced first, slowly, before something is added?
- Who else should know: the doctor who prescribes my opioid, my pharmacist, my pain clinic?
One pharmacy filling every prescription can flag a risky pairing automatically, and many pharmacists will review a full list, supplements included, on request.
How to talk to your doctor about hyperalgesia and cannabis
Set expectations first. A physician may decide cannabis is reasonable to try for your symptoms, or that it is not. Either way, nothing already prescribed changes without the doctor who prescribed it. A useful appointment focuses on one or two problems, your full medicine list and what “better” would look like for you.
Keep a pain diary
Two weeks of notes tell a physician more than any description from memory. Each day, write a line on:
- What set the pain off, if anything, and where it hurt.
- How strong it was on a 0 to 10 scale, and how long it lasted.
- How you slept: bedtime, wake-ups, how rested you felt.
- Every dose of pain medicine, opioids included, with the time.
- Anything that eased it.
Questions for your physician
- Could my rising pain be opioid-induced hyperalgesia rather than tolerance?
- What condition is driving this, and is it in my records?
- Would THC, CBD or neither make sense with my medicines?
- How would we tell within a few weeks whether it is helping, or hurting?
- What should I do about my sleep?
- Which signs mean stop immediately and call you?
What to bring
Tap each item once it is ready. Nothing is saved.
This guide summarizes published research for education and does not replace medical advice. Do not change opioids or other medicines without your prescriber.
Is hyperalgesia a qualifying condition for a medical marijuana card?
Not by that name. No state lists hyperalgesia itself. What qualifies is the diagnosis behind it, such as chronic or intractable pain, cancer, a neuropathy or migraine, where your state’s list includes it. Lists differ from state to state and change over time, and a licensed physician checks your records against the version in force on the day of the evaluation.
Listed condition
Your diagnosis is on the list
Chronic pain, cancer and similar conditions appear on many lists. A visit note recording the diagnosis is what the physician needs.
Physician discretion
Your state lets the physician decide
Some programs allow a physician to certify another serious or debilitating condition. It still has to be documented.
Not on the list
Nothing you have is listed
Your state may not offer a card for this yet. Some programs accept petitions to add conditions.
What has a doctor diagnosed?
Programs list diagnoses, not symptoms. Choose what is already in your medical records.
Chronic pain. The most common route for people with hyperalgesia; many states list chronic, severe or intractable pain. See chronic pain and medical cannabis.
Cancer. Listed in nearly every program, including pain from treatment. See cancer and medical cannabis.
Migraine. Named in some states, covered by broader pain wording in others. See migraine and medical cannabis.
Insomnia. Fewer states list it, but it often sits next to a pain diagnosis. See insomnia and medical cannabis.
Stroke. Central pain after a stroke may fall under a pain category. See brain ischemia and medical cannabis.
None of these. Then the decision rests on how your state words its list and on the physician’s judgment. Read getting a card without a listed condition and start with your state’s rules.
Every condition we cover is in all qualifying conditions.
Medical cannabis rules by state: legal status, possession limits, taxes, home cultivation
Four things change most from one state to the next: whether the state allows medical use only or adult use too, how much a patient may buy and hold, whether patients skip some cannabis taxes, and whether patients may grow plants at home. Where adult-use sales are legal, adults can buy without a card, yet a medical card still differs in several ways.
Taxes
With a medical card
Often lower; some states drop part of the cannabis tax for patients.
Buying recreationally
The full state and local cannabis tax.
How much you can buy and hold
With a medical card
Often more, by state rule.
Buying recreationally
The adult-use limit.
Home cultivation
With a medical card
Allowed for patients in some states, with a plant limit.
Buying recreationally
Allowed for adults in some adult-use states, often with a lower limit.
A physician’s review
With a medical card
Your diagnosis and medicines, opioids included, are looked at by a licensed physician.
Buying recreationally
No one reviews them.
The exact numbers for each state, and whether your diagnosis is on its list today, live on that state’s page and are kept current there. The tax side is compared in medical vs recreational cannabis taxes.
States where our physicians see patients. Each state’s page keeps its current condition list, possession limits, patient taxes and home-grow rules.
Medical marijuana laws by state · Using a card in another state
How to get a medical card online with hyperalgesia
Everything happens from home, and the card is issued for the condition behind your pain, not for the word hyperalgesia. Four steps, and only the first two need you at a screen.
-
About 5 minutes
Tell us the basics
Choose your state, list your diagnoses and medicines, and upload a note that records your diagnosis if you have one.
-
About 15 minutes
See a physician licensed in your state
A one-on-one appointment, all online. You agree on the time with the physician, who may run late with an earlier patient, so keep an hour free around it.
-
In as little as 15 minutes after the appointment, depending on your state
Get the signed recommendation
If the physician decides cannabis is appropriate, the signed document appears in your account.
-
Timing set by the state
Register with the state
Where the state runs a registry, you send it the recommendation, and the state issues the card on its own schedule.
Who runs the appointment
Across 250 reviews from patients in the states where we are licensed. We do not sort them by score and do not hide the low ones.
- 150,000+patients evaluated – everyone who has been through an appointment with us, in every state where we are licensed
- Since 2017doing only this: online evaluations for medical cannabis programs, and nothing else on the side
Every appointment is with a physician licensed in your state; the physicians are listed on our doctors page, and the process is explained in how the medical card works.
After you book
Your documents
The signed recommendation waits in your account. To move an appointment, use your appointments page; for anything else, write to support from your account.
Renewal
Cards expire on a schedule each state sets, and renewal means a fresh evaluation. Bring an updated medicine list and your pain diary. Common questions are in the medical card FAQ.
Price
The evaluation fee for your state is shown before you pay; a state fee, where one exists, goes to the state. Programs for veterans and for people on a low income cost less. Whether a recommendation is issued is the physician’s decision; what happens to the fee then is in the medical card FAQ.
Privacy, guns and work
Your medical records are protected by the HIPAA Privacy Rule [35]. Federal law still bars people who use a controlled substance unlawfully from owning guns, and cannabis remains federally controlled [36]. Workplace protections depend on your state; see laws and regulations.
Who wrote and reviewed this page
This guide was written by the Dr. Weedy editorial team and checked by the Dr. Weedy medical team, physicians licensed in the states where we work; their names are on our doctors page. The date of the last update and review is shown under the buttons at the top.
- Every research figure carries a citation you can open in the reference list at the end.
- Each study is labeled by who was studied, so a mouse result is never presented as a result in patients.
- Studies that found no added benefit, or that test something other than cannabis, stay on the page and say so.
- Nothing here promises an outcome; whether cannabis is reasonable for you is decided by a licensed physician.
Spotted something wrong or out of date? The feedback form at the end of this page goes straight to the editors.
Hyperalgesia and medical cannabis: questions people ask
Does hyperalgesia go away?
It often fades when its cause can be removed: an injury heals, inflammation settles or an opioid plan is changed with the prescriber. With lasting nerve damage or chronic pain it is usually managed rather than cured. Cannabis has not been shown to make it go away in people.
How do you treat hyperalgesia?
By treating what drives it, reviewing medicines such as opioids, and using nerve-pain medicines like gabapentin, pregabalin, duloxetine or amitriptyline, skin treatments such as lidocaine or capsaicin, and physical therapy, CBT and better sleep [14]. The full list is in how to treat hyperalgesia.
What is the difference between hyperalgesia and allodynia?
Hyperalgesia is too much pain from something that normally hurts a little. Allodynia is pain from something that should not hurt at all, like clothing or a light touch [1]. They often appear together. See the comparison table.
What does ketamine have to do with hyperalgesia?
Ketamine blocks NMDA receptors, which help the spinal cord amplify pain. Specialists sometimes use it under monitoring around surgery or for opioid-induced hyperalgesia. It is not a home treatment, and its use is a clinical decision.
Can cancer cause hyperalgesia?
Yes. Tumors can press on or damage nerves, and surgery, radiation and some chemotherapy drugs can sensitize them [7]. Many people with cancer also take opioids, so opioid-induced hyperalgesia is part of the picture. Cancer appears on nearly every state list; see cancer and medical cannabis.
Can hyperalgesia start after a stroke or shingles?
I take opioids and my pain is getting worse. What does cannabis have to do with it?
Rising pain on opioids can be opioid-induced hyperalgesia, and that is a conversation with your prescriber first [10]. Cannabinoids have been studied for OIH only in animals, and THC adds drowsiness to opioids. Cannabis is not a replacement for an opioid; see what is known so far.
Can tramadol cause hyperalgesia?
Tramadol is an opioid pain medicine, and the opioid-induced hyperalgesia warning on opioid labels applies to it [10]. If it seems to work less while pain spreads, tell the prescriber instead of taking extra doses.
Can Tylenol cause hyperalgesia?
Acetaminophen (Tylenol) is not an opioid and is not known as a cause of opioid-induced hyperalgesia. Some prescription painkillers combine acetaminophen with an opioid, such as hydrocodone or oxycodone, and the opioid part can. Check the label for both ingredients.
Is CBD-only or delta-8 the same as medical cannabis for pain?
No. Hemp-derived CBD and delta-8 products sold in stores are less tightly regulated, and the label may not match the contents. Delta-8 THC acts much like ordinary THC, with the same drowsiness and interaction risks, and CBD still changes how the liver clears other medicines [31].
Is an online evaluation legitimate?
Yes, in states whose law allows telemedicine for medical cannabis evaluations. The physician holds a license in your state, sees you one-on-one and signs the same recommendation an office visit would produce.
What is the ICD-10 code for hyperalgesia?
ICD-10-CM has no code titled hyperalgesia [13]. Clinicians code the condition behind it, or a group such as disturbances of skin sensation (R20) or pain not elsewhere classified (G89).
Can I get a medical card if my diagnosis is hyperalgesia?
Not for hyperalgesia by itself, since no state lists it. You may qualify through the diagnosis behind it, such as chronic pain, cancer or migraine, where your state lists it, and a licensed physician makes that decision. See qualifying conditions.
What if my card is lost?
The state program that issued it replaces it, usually through the same portal used to register. The steps are in what to do about a lost card.
More research on cannabis and hyperalgesia
This page cites a selection of studies. Our research library holds every study we track on cannabis and hyperalgesia, from laboratory work to clinical trials, and lets you filter them by cannabinoid, study type and year.
- studies
- 170+
- in people
- 100+
- clinical trials
- 8
More research and resources on hyperalgesia
Hyperalgesia rarely comes alone. These five conditions are linked to it as common causes or companions, and each page covers its own research and state rules.
Trusted resources
The International Association for the Study of Pain keeps the standard definitions of hyperalgesia, allodynia and related terms [1]. UK clinicians follow NICE Clinical Knowledge Summaries for nerve pain treatment [14], and the National Institute of Neurological Disorders and Stroke publishes plain-language guides on pain and its research [5]. Every study we track on the topic is in our research library.
Background reading
Talk to a licensed physician about hyperalgesia
What a physician can do: look at the condition behind your pain, your opioids and other medicines, and tell you whether cannabis is reasonable to discuss for your symptoms.
What cannabis cannot do: replace your prescribed treatment, or promise relief for hyperalgesia, which has not been tested in people.
The evaluation fee for your state is shown before you pay, and the physician decides whether a recommendation is right.
Trouble with the form? Write to support.
Share your experience
References
36 sources
- 1. International Association for the Study of Pain. IASP Terminology. 2017.
- 2. Merriam-Webster. Hyperalgesia, medical definition. 2026.
- 3. Centers for Disease Control and Prevention. Signs and symptoms of stroke. 2024.
- 4. National Institute of Neurological Disorders and Stroke. Shingles. 2025.
- 5. National Institute of Neurological Disorders and Stroke. Pain. 2025.
- 6. National Institute of Neurological Disorders and Stroke. Peripheral neuropathy. 2025.
- 7. National Cancer Institute. Cancer pain. 2024.
- 8. The endocannabinoid N-arachidonoyl dopamine is critical for hyperalgesia induced by chronic sleep disruption. DOI: 10.1038/s41467-023-42283-6 PMID: 37880241
- 9. Chronic stress and peripheral pain: Evidence for distinct, region-specific changes in visceral and somatosensory pain regulatory pathways. DOI: 10.1016/j.expneurol.2015.09.013 PMID: 26408049
- 10. U.S. Food and Drug Administration. FDA updates prescribing information for all opioid pain medicines to provide additional guidance for safe use. 2023.
- 11. Centers for Disease Control and Prevention. CDC Clinical Practice Guideline for Prescribing Opioids for Pain. 2022.
- 12. Intrathecal injection of JWH015 attenuates remifentanil-induced postoperative hyperalgesia by inhibiting activation of spinal glia in a rat model. DOI: 10.1213/ANE.0000000000000146 PMID: 24651239
- 13. Centers for Medicare and Medicaid Services. ICD-10 codes. 2026.
- 14. National Institute for Health and Care Excellence. Neuropathic pain: drug treatment, Clinical Knowledge Summaries. 2024.
- 15. Spinal endocannabinoids and CB1 receptors mediate C-fiber-induced heterosynaptic pain sensitization. DOI: 10.1126/science.1171870 PMID: 19661434
- 16. Heterosynaptic long-term potentiation of non-nociceptive synapses requires endocannabinoids, NMDARs, CamKII, and PKCζ. DOI: 10.1152/jn.00494.2022 PMID: 36883763
- 17. CB1 and CB2 cannabinoid receptor agonists induce peripheral antinociception by activation of the endogenous noradrenergic system. DOI: 10.1213/ANE.0b013e3182707859 PMID: 23302980
- 18. FABP5 deletion in nociceptors augments endocannabinoid signaling and suppresses TRPV1 sensitization and inflammatory pain. DOI: 10.1038/s41598-022-13284-0 PMID: 35655086
- 19. Glucocorticoid-endocannabinoid crosstalk in the ventrolateral periaqueductal gray (vlPAG) promotes pain resolution. DOI: 10.1038/s41386-026-02529-5 PMID: 42618595
- 20. Allosteric Cannabinoid Receptor 1 (CB1) Ligands Reduce Ocular Pain and Inflammation. DOI: 10.3390/molecules25020417 PMID: 31968549
- 21. Vanilloid TRPV1 receptor mediates the antihyperalgesic effect of the nonpsychoactive cannabinoid, cannabidiol, in a rat model of acute inflammation. DOI: 10.1038/sj.bjp.0705920 PMID: 15313881
- 22. Electroacupuncture alleviates morphine‑induced hyperalgesia by regulating spinal CB1 receptors and ERK1/2 activity. DOI: 10.3892/mmr.2019.10329 PMID: 31173210
- 23. Anti-nociceptive and desensitizing effects of olvanil on capsaicin-induced thermal hyperalgesia in the rat. DOI: 10.1186/s40360-016-0074-9 PMID: 27439609
- 24. Upregulation of fatty acid amide hydrolase in the dorsal periaqueductal gray is associated with neuropathic pain and reduced heart rate in rats DOI: 10.1152/ajpregu.00481.2016 PMID: 28148494
- 25. Alternative Splicing Mechanisms Underlying Opioid-Induced Hyperalgesia. DOI: 10.3390/genes12101570 PMID: 34680965
- 26. Role of Endocannabinoid System in the Peripheral Antinociceptive Action of Aripiprazole. DOI: 10.1213/ANE.0000000000003723 PMID: 30198932
- 27. Peripheral interactions between cannabinoid and opioid receptor agonists in a model of inflammatory mechanical hyperalgesia. DOI: 10.1016/j.brainresbull.2016.07.009 PMID: 27450703
- 28. Participation of cannabinoid receptors in peripheral nociception induced by some NSAIDs. DOI: 10.1590/s0100-879×2012007500153 PMID: 22983178
- 29. Inflammatory hyperalgesia induces essential bioactive lipid production in the spinal cord. DOI: 10.1111/j.1471-4159.2010.06815.x PMID: 20492349
- 30. U.S. Food and Drug Administration. FDA and cannabis: research and drug approval process. 2024.
- 31. U.S. Food and Drug Administration. Epidiolex (cannabidiol) prescribing information. 2018.
- 32. National Highway Traffic Safety Administration. Drug-impaired driving. 2024.
- 33. National Center for Complementary and Integrative Health. Cannabis (marijuana) and cannabinoids: what you need to know. 2024.
- 34. Centers for Disease Control and Prevention. Cannabis health effects. 2024.
- 35. U.S. Department of Health and Human Services. The HIPAA Privacy Rule. 2024.
- 36. Legal Information Institute, Cornell Law School. 18 U.S. Code 922: Unlawful acts. 2024.