Can cannabis help relieve pain?

Statistics show that the use of cannabis among adults ages 65 and older has increased eightfold in recent years, and as many as 80% of these seniors use it to treat and manage pain. But can it really help?

"Cannabis has been used for medical purposes for thousands of years," says Staci Gruber, director of the Cognitive and Clinical Neuroimaging Core and the Marijuana Investigations for Neuroscientific Discovery (MIND) program at Harvard-affiliated McLean Hospital. "Still, there is much we don’t know about how it works and for what conditions. But pain management is an area where both science and personal anecdotes tend to support its use."

Cannabis 101

Cannabis is derived from hemp or marijuana. These plants are two varieties of the same species: Cannabis sativa. The plant contains more than 100 chemical compounds called cannabinoids. The two most prevalent compounds are tetrahydrocannabinol (THC) — which is what gives people a "high" — and cannabidiol (CBD), which doesn’t produce an intoxicating effect.

One difference between hemp and marijuana is how much THC they contain. Marijuana has more than 0.3% THC by weight, while the amount in hemp is equal to or less than 0.3% THC by weight. Marijuana also contains less CBD than hemp.

Hemp is used to make the various CBD products that have popped up everywhere. They are available thanks to the 2018 Farm Bill, which legalized industrial hemp plants to make various types of merchandise — mostly paper, textiles, and concrete — but it also opened the door for CBD products.

What the science says

The thinking is that when ingested or inhaled, THC or CBD binds to specific receptors on the brain and nerve cells, which slows pain impulses and eases discomfort. "They also may provide anti-inflammatory effects, which may help reduce pain," says Gruber.

People who take cannabis for pain relief vouch for its effectiveness. However, the science behind it has been thin. Part of the problem is the lack of double-blind, randomized, placebo-controlled studies — the gold standard for medical research. Still, other types of studies have shown that cannabis can help with certain conditions, including pain.

In 2017, a committee formed by the National Academies of Sciences, Engineering, and Medicine reviewed about 10,000 studies related to cannabis use for medical indications. The experts weighed the strength of the evidence for almost two dozen health conditions. They found "substantial" or "conclusive" proof that cannabis was an effective treatment for only three health problems, one of which was pain. (The other two were spasms related to multiple sclerosis and chemotherapy-induced nausea and vomiting.)

However, it’s also possible that part of cannabis’ healing power represents a placebo effect. People think it will work, so it does. An analysis published Nov. 28, 2022, in JAMA Network Open looked at 20 randomized controlled studies regarding the effect of cannabis products on pain relief and found that placebos were as effective.

Is it for you?

Should you try cannabis for your pain? According to Gruber, it depends on the type of pain, the severity, and your expectations. "While there is evidence that people can find pain relief from  cannabis, this doesn’t mean it works for everyone or every type of pain. Nor does it mean it will treat the overall problem causing your pain," she says.

Doctors can’t prescribe cannabis like conventional medications, but in many states, they can recommend its use for certain conditions, including pain. (Check out your state’s cannabis laws at /mm.)

Depending on where you live, this recommendation will allow you to legally buy cannabis from licensed dispensaries. However, in states where recreational cannabis is legal, people can purchase cannabis at dispensaries and online without a doctor’s input. Still, always consult your doctor before trying any cannabis product, so you can discuss possible side effects, like dry mouth, impaired mental function, dizziness, and heart and blood pressure problems, or interactions with other medications you are taking.

Individuals who want to avoid the "high" associated with THC can choose cannabis products with more varied cannabinoid profiles, says Gruber. "These include CBD and other non-intoxicating compounds from the plant that may have therapeutic benefits."

However, be careful about using over-the-counter CBD products, as they lack oversight (since the FDA has yet to develop CBD regulations). "Right now, there is no way to know whether a product contains the amount of CBD indicated on the label or if it contains things it shouldn’t," says Gruber.

Cannabis can be consumed in different ways. You can smoke the leaves via a joint, pipe, or bong; inhale vaporized leaves or oil; consume it through edibles like brownies, cookies, gummies, or tea; take as an oil or tincture under the tongue; or apply it to the skin via topical creams or patches.

How often people take cannabis for pain also varies. "Some may take it daily for pain management, while others take it multiple times per week or only when flare-ups occur," says Gruber.

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