Log in

Get your medical card online in minutes!

Get started

Why Medical Marijuana Works for Pain


The jury is out as to whether or not cannabis functions as a painkiller and for what degrees of pain (mild, moderate, or severe) it is useful. However, much of the evidence so far suggests that cannabis does work for chronic pain.

As for nerve-related neuropathic pain, cannabis may provide short-term pain relief for one in five to six patients.

However, due to legal status and the difficulty in getting research funding for cannabis-related studies, much of how cannabis works as a painkiller is not understood. Therefore, many reasons why cannabis might work for pain are not known precisely.

So much is conjecture and supposition based on the available evidence we have.

Get your medical marijuana card

Connect with a licensed physician online in minutes.

Types of Pain

There are several types of pain, usually broken down into three categories: Short-term or acute pain, long-term or chronic pain, and recurrent or intermittent pain.

marijuana for pain

There are also other categories of pain, which can generally fit under one of the above. These include:

  • Soft Tissue: Caused by damaged or inflamed organs, muscles, or tissues.
  • Neuropathic/Nerve Pain: Caused by damaged nerves. Those who have cancer, diabetes, HIV/AIDS, multiple sclerosis (MS), and many other conditions that affect the nervous system, spinal cord, and brain can cause a condition known as peripheral neuropathy.
  • Bone Pain: Aching bones across the body or in a region of the body. Bone pain is known to be a symptom of cancer, but not all bone pain is cancer.
  • Breakthrough Pain: Pain that occurs in between regular, scheduled painkillers.
  • Referred Pain: Pain that emanates from one part of the body but is felt in another.
  • Phantom Pain: Pain in a part of a body that has been removed, such as an amputated limb.
  • Total Pain: A concept developed by Cicely Saunders, founder of the modern hospice movement. Total pain includes the combination of physical, psychological, social, and spiritual pain.

Anxiety, depression, stress, lack of sleep, decreased appetite, and emotional turmoil are all also associated with pain and can often worsen physical pain. Cannabis, unlike many other medications, may be able to help beat many different kinds of pain.

Download Our Free Guide to Marijuana and Chronic Pain

How Does Cannabis Work to Reduce Pain?

Nobody knows precisely. However, there are several reasonable theories. The paper, ‘Role of the Cannabinoid System in Pain Control and Therapeutic Implications for the Management of Acute and Chronic Pain Episodes,’ explains how cannabis might work as a painkiller more effectively. Cannabis might help control pain by:

Regulating Nociceptor

Nociceptors are receptors responsible for detecting pain, and cannabinoids can regulate pain thresholds. Both THC and CBD can help control the pain signals received by nociceptors.

Inhibiting the Release of Pro-Inflammatory Factors by Non-Neuronal Cells

Cannabinoids act as anti-inflammatories, inhibiting cytokine production. This can be particularly useful for autoimmune disorders, where inflammation is out of control.

Indirectly Stimulating μ-Opioid and δ-Opioid Receptors

THC and CBD change the way receptors receive pain signals. This is one of the reasons why medical cannabis can be used to replace opioids, and this factor also gives cannabinoids potential use in reducing sedatives and alcohol as well.

Regulating the Endocannabinoid System (ECS)

The ECS is connected to regulating pain, reward, memory, and appetite. It also assists in promoting homeostasis.

Acts on Both Nerve and Non-Nerve Tissues

Making cannabis potentially effective for controlling neuropathic pain and other types of pain — something opioids cannot do.

Medical Marijuana: Pain Killer or Pain Distractor?

In a brain imaging study by researchers at Oxford University, 12 participants were given 15 mg THC tablets or a placebo to see if THC would lessen the pain from a cream containing capsaicin — the ingredient in chili that causes a hot, burning, and painful sensation. Non-painful dummy creams were also used as a control. Each participant was given 4 MRI scans.

The results? Six out of 12 participants reported an evident change in how much the pain bothered them. The burning sensation didn’t lessen, but the THC tablets seemed to bother the individuals less.

The brain imaging results showed suppression of activity in the mid-cingulate cortex, which has been implicated in the emotional aspects of pain. The right amygdala also showed changes in activity, which correlated with lessening pain after using THC.

There’s another exciting piece of information arising from this study: researchers found the strength of the connection between an individual’s right amygdala and a part of the cortex known as the primary sensorimotor area — the main receptive area of the brain responsible for the sensation of touch.

This suggests that we may one day be able to figure out for whom cannabis would be an effective painkiller and for whom it would not.

Dr. Lee, one of the researchers, noted, “Cannabis does not seem to act like conventional pain medicine. Some people respond well, others do not, or even poorly. Brain imaging shows little reduction in the brain regions that code for the sensation of pain, which is what we tend to see with drugs like opiates. Instead, cannabis appears to mainly affect the emotional reaction to pain in a highly variable way.”

This helps explain why, for some people, cannabis may well increase their pain sensitivity or why using small amounts decreases pain in some individuals but increases pain sensation at higher doses.

The efficacy of cannabis as a painkiller is not fully known, and what may work for one person may not work for another. Another thing to remember is that this study only considered THC in isolation, meaning that other cannabinoids and terpenoids were not researched.

Phytocannabinoids and the Endocannabinoid System

Cannabis contains hundreds of cannabinoids, of which two are in greater abundance than the others (and therefore most commonly studied): tetrahydrocannabinol (THC) and cannabidiol (CBD). Both of these work on CB1 and CB2 receptors, directly or indirectly.

CB1 receptors are found in the central nervous system (CNS), lungs, liver, and kidneys. CB2 receptors are found in the peripheral nervous system (PNS) and are expressed in immune and blood cells.

THC is said to work on the CB1 receptors (and one of the reasons why it is said to have a psychoactive effect), whereas CBD is said to work on CB2 receptors.

Other, more minor cannabinoids may also have painkilling properties.

Cannabigerol (CBG) is one such cannabinoid. Unfortunately, these cannabinoids are not usually found in abundance in cannabis plants, making them more challenging to study. However, likely, these contribute just as much to the entourage effect as THC and CBD do when working together.

Medical Marijuana, Terpenes, and Chronic Pain

Often forgotten, terpenes/terpenoids are just as crucial as cannabinoids, interacting in exciting ways. After all, terpenoids can affect how cannabinoids behave, even when the cannabinoids are of equal concentration.

This means that a 1:1 THC:CBD ratio where the primary terpenes are myrcene and linalool will have quite different effects than a 1:1 THC:CBD ratio with limonene and pinene.

Terpenes also have painkilling properties of their own. Myrcene and linalool are both analgesics, while terpenes like caryophyllene function as anti-inflammatories. The mood-elevating effects of terpenes like limonene may help beat depression, which may also help reduce pain.

Medical Marijuana, Serotonin, Adenosine, and Other Receptors

CBD may work on other receptors in the body that THC doesn’t on its own — at least, not to the extent CBD does, especially when combined with some THC. The other receptors CBD affects include:

Serotonin Receptors, Chronic Pain, and Medical Marijuana

Cannabis binds to serotonin receptors, which can have a beneficial effect on managing chronic pain. CBD interacts with serotonin receptors and may be a supplemental treatment for chronic pain.

Adenosine Receptors, Chronic Pain, and Medical Marijuana

Adenosine receptors play a role in releasing the neurotransmitters dopamine and glutamate. Targeting adenosine receptors may make cannabis useful for neuropathic (nerve-related) pain.

Vanilloid Receptors, Chronic Pain, and Medical Marijuana

Transient Receptor Potential Cation Channel Subfamily V member 1 (TRPV1) plays a part in mediating inflammation, pain perception, and body temperature. Inhibiting this receptor may help reduce pain, as CBD blocks or occupies the area’s pain signals from being sent.

Methods of Ingesting Cannabis for Chronic Pain: Pros and Cons

So, which method of using cannabis is best for pain? This depends upon the individual, but here are some of the most popular ways of ingesting cannabis and what their pros and cons are:

Smoking Medical Cannabis

Although cannabis smoke and tobacco smoke are pretty different (one big difference is that cannabis doesn’t contain nicotine), people may be wary of inhaling any smoke. Yet, smoking cannabis is still quite popular among many medical marijuana users.


The effects can be felt immediately. It’s relatively simple to control the amount you use each time, and many people enjoy the hands-on process of sitting down and rolling their joints.

The negatives?

Smoking cannabis might not be the ideal route of administration for most patients (i.e., they cannot or should not smoke), and the precise effects of inhaling cannabis smoke are not fully understood yet.

Vaporizing Medical Cannabis

As with smoking, vaporizing can bring immediate relief — without the smoke. Vaporizing is also easy to measure, as it is possible to take the amount you need to find relief and then store it away until you need it again.

However, the long-term health effects of vaporizing cannabis are not known yet; for some people, vaporizing is ineffective. It is also worth being wary of the quality of vaporizers — a bad one may mean melting plastic, metal filings, and broken parts, which can potentially cause serious health problems.

Consuming Cannabis Edibles

Many people who suffer from chronic pain seem to find relief from edibles, likely due to the powerful, long-lasting effects. Edibles are also perhaps one of the most economical ways of using cannabis.

The problems? Effective dosing, the lack of regulation and standardization concerning edibles (many aren’t tested and appropriately labeled), and even small amounts can be overwhelming for some. Edibles can take some time and may not be ideal for immediate pain relief.

Using Cannabis Tinctures and Sprays

Tinctures usually have similar effects to edibles, with the impact tending to come on quicker. The dropper also tends to make dosing easier, and getting a hold of the right tincture is arguably more reliable than getting a hold of the right edible.

The advantage of being non-descript is that tinctures don’t tend to smell as strongly as vast clouds of vapor or smoke, and a few drops can easily be put into your coffee. Many tinctures are also whole plant extracts, which means all the cannabinoids and terpenes remain in the product.

The disadvantages? There can be a thin line between pain relief and overwhelming pain relief. For people extremely sensitive to THC, even a slightly higher dose may prove to be a problem. However, this is generally rare, and a well-made tincture is probably one of the best ways of utilizing cannabis as medicine.

Dabbing Cannabis

Oils, waxes, and concentrates are extremely high in THC or CBD. While this high THC level may be helpful for fast, substantial pain relief, it is probably not ideal for beginners. Concentrates may also be stripped of other terpenes, meaning that some medical benefits of cannabis may be lost.

Side Effects of Using Medical Marijuana for Pain

There are all sorts of positive side effects of medical marijuana, depending on the strain you use and the effect you’re seeking. Some people are just looking for relief without the psychoactive effects during the day but may prefer some psychoactive effects when trying to sleep at night, socialize with friends and family, or seek a distraction from their pain.

Of course, being sleepy may not be ideal for some, especially if work or fun needs to be done. Taking too much cannabis may cause one to green out and make a person nauseous and vomit.

There’s another, oft-relegated issue: taking some may reduce your pain, while taking more may increase your pain and anxiety. This can make effective dosing difficult, so it is essential to try several different products/strains and take them slow and low. Try various methods of ingestion to see what works best for you.

Another issue is that, for some people, ingesting any amount of cannabis may increase their pain sensitivity. This can be even more complicated because cannabis may interact negatively with other prescribed painkillers, like benzodiazepines and opioids (even though cannabis can also reduce intake in many instances).

Cannabis for Physical, Mental, Emotional and Total Pain

Constant, chronic physical pain may start as being just physical. Over time, physical pain can become wearisome and lead to improper sleep (insomnia), a weakened immune system, anxiety, and depression. These symptoms can worsen physical pain, as depression, anxiety, and insomnia feed into and accompany the physical pain.

Unlike many other drugs, the advantage of cannabis is that you can use one medication for multiple uses rather than several different medications. Popping several pills numerous times a day can be psychologically harmful.

Spiritual pain is a nebulous concept that is extremely difficult to measure. We have only started to understand physical pain properly over the past 50 years (30 years, as the endocannabinoid system plays a fundamental role in pain detection), and we are still trying to figure out mental and emotional pain.

However, to negate or handwave away the role of spiritual pain would be a disservice, primarily because we focus so much on the philosophical aspects of the word spiritual. However, if we take the word spiritual to mean connectedness to others and to nature, we might be able to grasp the idea better.

There are arguably several health problems, including depression, anxiety, post-traumatic stress disorder (PTSD), and addiction, where a lack of connectedness and a feeling of emptiness or emotional flatness is a significant concern. However, as this pain cannot be measured easily, creating medication for it is challenging.

Cannabis, however, has often been noted for its consciousness- and creativity-expanding properties, as well as its ability to keep one relaxed and focused. On top of this, cannabis is a whole plant, increasing its connection to nature for many. There are few if any, drugs or medications out there that can treat different types of pain the way cannabis does.

The Bottom Line

Cannabis’s biochemical complexity means that its ability to control and manage pain is difficult to pinpoint accurately, especially considering all the variables. One particular strain or product might make one person pain-free, whereas another person’s pain might be exacerbated using the same strain or product.

This is why, if you’re trying to manage your pain with medical marijuana, it is best to try several different products and strains and go low and slow (i.e., try a little bit at a time).

The doctors at Leafwell can help you apply for a medical marijuana card to treat any pain you may be experiencing. Connect with us today, and we’ll start you on becoming pain-free with cannabis medicine.

Get Your Medical Card

Connect with a licensed physician online in minutes.

Originally Published: October 2021

Last Updated: April 2024

Keep Reading