People have been using variations of the cannabis plant for thousands of years. Now, cannabis and its derivatives are being looked at as a potential therapy for medical conditions like multiple sclerosis (MS). However, more research is needed – particularly large-scale trials that are randomized and double-blinded (neither the doctors nor the patients know if they are getting cannabis or a placebo) – before cannabis can be justified as a proven therapy.

Traditionally, the smoking form of cannabis has been called marijuana, although some oral formulations are now also called marijuana. While cannabis for recreational or medicinal use is illegal by federal law, several individual states have passed laws making medical marijuana legal, and a few states have also made recreational use of marijuana legal. After federal legislation was passed in 2005, federal funds are currently not being used to enforce federal law in states that allow marijuana use.1 Each individual should consult with their doctor and the laws of the state they reside in before considering the possibility of using medical marijuana.

What are the differences between CBD and THC?

While there are over a hundred different compounds (called cannabinoids) in cannabis, the two most commonly studied are THC (delta-9-tetrahydrocannabinol) and CBD (cannabidiol). THC has been associated with reduction of nausea and pain, increased appetite, and psychological effects like euphoria, anxiety, and altered sensory perception, which can make users feel “high” or intoxicated. CBD does not produce intoxicating effects, but it produces sedative effects that can help reduce pain, convulsions, nausea, and inflammation. There are a variety of preparations with varying doses of CBD and THC. However, there isn’t enough research on the different ratios or different preparations (oral, topical, or inhaled) to know which is best for people with MS.2,3

Why do people with MS use medical marijuana?

Since there is no cure for MS, current treatments aim to reduce symptoms and slow or stop the progression of the disease. Some people with MS do not get relief from their symptoms with currently available therapies, leading them to investigate complementary or alternative medicines, like cannabis. Studies have found that a significant number of people living with MS are using or considering using cannabis to help with their MS symptoms.2,3

While there are still many unknowns about the positive and negative effects of cannabis in people with MS, some studies have demonstrated a benefit on muscle spasticity and pain. These positive effects have been confirmed by the American Academy of Neurology (AAN).1,2

What do the guidelines say?

The AAN issued guidelines in 2014 based on a review of the evidence available on cannabis. The guidelines state that:

  • Physicians might suggest cannabis to their patients with MS for the possible relief of patient-reported spasticity and pain (excluding central neuropathic pain), but patients should be aware that cannabis is probably not effective for tremor, urinary incontinence, or for spasticity as measured by the physician
  • The long-term safety of marijuana use by people with MS has not been established
  • While the oral preparations of cannabis have demonstrated some effectiveness on spasticity and pain, studies of smoked cannabis have not produced enough evidence to support its use1,4,5

What is nabiximols?

Nabiximols is a liquid extract of two types of cannabis and is formulated as an oral-mucosal spray. In clinical trials, nabiximols has demonstrated effectiveness in reducing MS-related spasticity that has not been adequately treated by other pharmaceuticals. Nabiximols is available in several European, South American, and Scandinavian countries, as well as Canada, Australia, and New Zealand as Sativex® (delta-9-tetrahydrocannabinol and cannabidiol). Sativex has not received FDA approval and is not currently available in the U.S. Common side effects of nabiximols in clinical trials were dizziness (experienced by 27.5% of patients taking nabiximols), diarrhea (13.1%) and fatigue (11%). None of the patients in the clinical trials experienced withdrawal symptoms when treatment was stopped.6,7

What are the biggest challenges facing research on cannabis?

There are many questions that remain unanswered regarding cannabis use, such as:

  • Which MS symptoms are best treated with cannabis?
  • What is the best ratio of CBD to THC to treat MS symptoms?
  • Is there a difference in effectiveness between synthetic and plant-derived cannabinoids?
  • What is the best frequency of dosing?
  • Is there a difference in effectiveness or safety by the route of administration (smoking, edibles, drops, oral-mucosal spray, etc.)?

While there is clearly a need for more research to understand the benefits and risks of cannabis and the differences in various strains or preparations, in the U.S., there is a lack of funding for this kind of research. The vast majority of research dollars currently available for cannabis is by the National Institute of Drug Abuse, whose aim is to understand drug abuse and addiction, not the potential medical benefits of cannabis. Also, as a controlled substance, researchers must obtain approval from several governmental agencies before conducting trials with cannabis, and few laboratories currently meet the necessary requirements.2

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Written by Emily Downward | Last review date: February 2022.