Cannabis-Based Medicines for MS Have Mild Side Effects But Raise Concerns for Psychosis-Prone and Pregnant Patients | Research

The takeaway

Clinical trial data showed cannabis-based MS medicines had generally mild side effects (dry mouth, dizziness, somnolence), but the review urged caution for people predisposed to psychosis and pregnant women, and noted therapeutic benefits were still modest.

Read this if you are considering cannabis-based treatment for MS and want to understand the safety evidence.

Side effects generally mild (dry mouth, dizziness) but caution urged for psychosis-prone and pregnant patients

What the researchers found

This review assessed the safety profile of cannabis-based medicinal extracts (CBMEs) for MS treatment. Clinical trial data showed adverse effects were generally mild: dry mouth, dizziness, somnolence, nausea, and intoxication. No cases of toxicity developed.

Despite evidence that cannabinoids can disrupt cognitive function and promote depression in recreational users, these adverse effects appeared unlikely with CBMEs based on available data. Effects on balance, motor control, and immune function also appeared clinically insignificant.

However, the review identified two populations warranting concern: people predisposed to psychosis, given growing evidence of cannabis-psychosis links, and pregnant women, given increasing evidence of adverse fetal effects. The author concluded that given the modest therapeutic benefits demonstrated so far and the risk of unknown long-term effects, caution was warranted.

Why it matters

This review provided an honest assessment of both the safety and the limitations of cannabis-based MS medicines. The identification of specific at-risk populations (psychosis-prone individuals and pregnant women) helped guide clinical decision-making about who should and should not use these treatments.

The numbers in context

Common adverse effects: dry mouth, dizziness, somnolence, nausea, intoxication. No toxicity in any trial. Most trials ran only months long. Specific concerns: psychosis-predisposed individuals and pregnant women.

How the study worked

Safety review of clinical trial data on cannabis-based medicinal extracts for MS. Evaluated adverse effect profiles, cognitive impacts, effects on balance and motor control, immune function, psychosis risk, and reproductive safety.

What this study cannot tell us

Most clinical trials were relatively short (months), limiting knowledge of long-term safety. The review noted that unknown adverse effects could develop with longer use. The assessment of psychosis and pregnancy risks drew partly from recreational cannabis research, which may not directly apply to pharmaceutical preparations.

How to read the evidence

Safety review synthesizing clinical trial data. Limited by the short duration of most trials and the difficulty of extrapolating long-term risks from short-term data.

When this study was published

Published in 2005. Long-term safety data from post-marketing surveillance of Sativex has since become available, providing a clearer safety picture.

The bigger picture

The cautious tone of this review, noting modest benefits and unknown long-term risks, contrasts with more enthusiastic assessments of cannabis-based medicines. This balanced perspective influenced regulatory decisions about labeling and prescribing guidelines for products like Sativex.

Questions still open

Do the long-term safety profiles of cannabis-based medicines differ from those of recreational cannabis? At what level of psychosis predisposition should cannabis-based medicines be contraindicated?

Common questions

Are cannabis-based MS medicines safe?

Short-term clinical trial data showed generally mild side effects. However, this review noted that most trials lasted only months, potential long-term effects were unknown, and specific caution was warranted for people predisposed to psychosis and for pregnant women.

Who should avoid cannabis-based medicines?

The review specifically identified two groups warranting concern: people predisposed to psychosis (given evidence linking cannabis to psychotic episodes) and pregnant women (given evidence of adverse effects on fetal development).

Read the original research

The safety of cannabinoids for the treatment of multiple sclerosis.

Expert opinion on drug safety, 4(3), 443-56

View on PubMed ↗

Citation

Smith, Paul F. (2005). The safety of cannabinoids for the treatment of multiple sclerosis.. Expert opinion on drug safety, 4(3), 443-56.