These products are increasingly being legalized for medical uses across the United States, but it’s important to take certain precautions into consideration before you head to your local dispensary (in states that have them). Indeed, the NMSS emphasizes that, to date, most studies involving the drug and its derivatives have included “relatively small numbers of people with MS” and used different measures for effectiveness. “We have to ask ourselves, what is the level of evidence?” says Vijayshree Yadav, MD, the clinical director of the multiple sclerosis center at Oregon Health and Science University in Portland, who published a review in Neurology on the subject in March 2014. “It’s one thing for clinical studies to evaluate a standardized marijuana medicine,” Dr. Yadav says. “But evaluating marijuana when a patient smokes or eats it is another story, because marijuana varies so widely from sample to sample. Concentrations of its active ingredients differ, and so researchers can’t accurately compare its effects.” Still, with medical marijuana becoming a hot topic for a lot of people with chronic conditions, it’s important to know what options you have available and whether or not they’re worth investigating if you have multiple sclerosis. Here’s an overview of what’s known so far.

General Findings for Marijuana in MS 

As the NMSS notes, reviews of published studies of synthetic marijuana-based products derived from the cannabis plant have generally demonstrated that these treatments can help alleviate MS symptoms like pain and spasticity. But they also emphasize that many of these studies have significant shortcomings, including size (number of participants enrolled) and design. One review of existing research, for example, presented at the annual meeting of the Consortium of MS Centers in June, identified 60 studies of marijuana derivatives in the treatment of MS symptoms, of which only 26 were randomized controlled studies (considered the gold standard for medical research). Notably, the researchers concluded that 22 studies were considered to be poor quality, 14 were fair quality, and 24 were good or excellent quality. Although the findings of the studies included in the analysis generally suggested that these products showed “a trend of reducing spasticity, pain, and balance or walking difficulties in individuals with MS,” with minimal side effects, the authors noted that “the variable quality … requires consideration when examining results of individual studies.” Similarly, a systematic review of 31 randomized controlled trials of marijuana derivatives published in February 2018 in the journal Canadian Family Physician found that some of the study participants (some of whom had MS) who took cannabinoids achieved pain reduction of at least 30 percent, along with a corresponding improvement in spasticity. But the authors also noted that larger and longer randomized controlled trials found no benefit for marijuana use in pain and spasticity. In other words, larger and better studies of the use of marijuana-based products for the treatment of MS are needed. For its part, the American Academy of Neurology, in its most recent review of the efficacy and safety of medical marijuana in selected neurologic disorders, published in 2014, states that evidence supports the effectiveness of oral cannabis extract in reducing spasticity and some forms of pain in people with MS. But it also cautions that people with MS who use marijuana outside of clinical trials have been observed to have an increase in cognitive impairment.

Effects of Cannabidiol (CBD) vs. Tetrahydrocannabinol (THC)

To date, two of marijuana’s active components, cannabidiol (CBD) and delta-9-tetrahydrocannabinol (THC), have been extracted from the cannabis plant or synthesized (made in a laboratory) for medical use. THC has a stronger intoxicating effect than CBD, according to the National Institute on Drug Abuse. Clinical trials have indicated that THC, considered the main psychoactive component in marijuana, has the potential to be effective in treating the spasticity, muscle stiffness, and rigidity experienced by people with MS.

For example, a study of Sativex (nabiximols), an oral spray that combines THC and CBD, published in November 2016 in the journal European Neurology found that among 281 people with MS spasticity who used the spray for three months (at a mean dosage of six sprays per day) spasticity and spasticity-related symptoms (muscle spasms, fatigue, pain, poor sleep quality, and bladder dysfunction) were significantly improved. Sativex has been approved in Canada and many European countries for use as add-on therapy to reduce spasticity in people with MS, but hasn’t yet been cleared by the U.S. Food and Drug Administration (FDA).

Marinol and Cesamet Reduce Pain

Two marijuana-derived drugs that have received FDA approval, Marinol (dronabinol), or synthetic THC, and Cesamet (nabilone), which has a similar chemical structure to THC, for therapeutic uses (primarily in those with HIV/AIDS), haven’t been cleared for people with MS, due in large part to the lack of large clinical trials demonstrating their safety and effectiveness. Still, the evidence that exists shows promise. For example, a study of Marinol in 100 adults with neuropathic pain from MS, published in November 2017 in the journal European Neurology, found that the THC derivative reduced pain more effectively than placebo, with little evidence of drug abuse (only one case of dependency reported). Study participants rated their pain on a 0-to-10 scale and reported an average reduction of 1.92 after 16 weeks of treatment with Marinol (compared with 1.81 for the placebo). Similarly, a study of adding Cesamet to Neurontin (gabapentin) in 15 adults with MS-induced neuropathic pain, published in January 2015 in the journal Pain Medicine, found that treatment reduced pain and lessened the impact of pain symptoms on daily living compared with placebo.

No Evidence for Smoking or Eating Marijuana

There is still no clinical evidence to support MS symptom improvements from smoking marijuana, or from eating it when it’s baked into foods such as brownies, notes Dr. Yadav. What’s more, marijuana can cause slower, less predictable effects when it’s eaten rather than smoked, according to the U.S. National Library of Medicine.

Public Interest in Marijuana Products Is High, but Side Effects Are a Concern

Although the clinical benefits of marijuana use in MS still require further investigation, many people with MS express interest in trying it, and some already are. For example, a survey of 251 people with MS published in January 2019 in the American Journal of Managed Care found that 74 percent were interested in using marijuana derivatives to treat their symptoms (although 95 percent agreed more research was needed). Among the 19 survey respondents already using CBD-only products to treat their MS symptoms, the most common reasons for use were spasticity or muscle tightness (42 percent), pain (32 percent), insomnia or poor sleep (21 percent), and muscle spasms (21 percent). Among the 56 respondents who used THC-only or blended THC-CBD products, the most common reasons for use were pain (52 percent), insomnia or poor sleep (32 percent), spasticity or muscle tightness (23 percent), and muscle spasms (20 percent). For all THC or CBD products, weight gain and cognitive impairment were the most bothersome and worrisome side effects — and it’s the latter that concerns Yadav the most. “Given that decline in cognitive function is a common symptom of MS, the fact that marijuana-based treatments may also affect cognitive function is significant,” she says. “That’s something I emphasize with my patients who ask about marijuana.” It’s also worth noting that little is known about potential drug interactions between cannabis-based medications and MS drugs.

Yadav practices in Oregon, one of 30 states (plus Washington, DC) in which medical use of marijuana has been legalized, as of January 2019. With more states considering legalization, it’s not surprising that there are several new THC or CBD products currently being evaluated for a number of medical conditions, including MS. But marijuana is still classified by the U.S. government as a Schedule I substance under the Controlled Substances Act. Thus, distributing it is still considered a federal offense. “There is definitely a lot of buzz around medical marijuana these days, and I do have patients asking about it,” Yadav says. “But there is still a lot we need to learn about its potential benefits, and risks, before we can recommend it safely to people with MS.” Additional reporting by Brian P. Dunleavy.