THC and Cannabis-Based Products for Multiple Sclerosis
Nabiximols (Sativex) oromucosal spray containing THC and CBD is probably effective for reducing patient-reported spasticity symptoms and pain in MS patients, though it does not improve objective measures of spasticity. 1, 2, 3
First-Line Recommendation for Spasticity
Clinicians might offer nabiximols oromucosal cannabinoid spray for spasticity symptoms, pain, and urinary frequency in MS patients who have failed conventional therapies. 2 The evidence shows:
- Nabiximols probably increases the number of people reporting important reduction in perceived spasticity severity (odds ratio 2.51, with 216 more people per 1000 reporting benefit compared to placebo) 4
- The spray is probably ineffective for objective physician-measured spasticity and urinary incontinence 2
- Most patients in clinical trials used between 20-40 mg of THC daily in divided doses 3
Alternative Cannabinoid Formulations
Clinicians might offer oral cannabis extract (OCE) or synthetic THC (dronabinol) for spasticity symptoms and pain, excluding central neuropathic pain. 2 However:
- Oral cannabis extract is Level A evidence for spasticity symptoms and pain 2
- Synthetic THC (dronabinol) is Level B evidence for the same indications 2
- Both are probably ineffective for objective spasticity measures in the short-term 2
- Both are possibly effective for spasticity and pain with long-term use 2
Recent Evidence on Vaporized Cannabis
A 2025 study demonstrated that vaporized CBD 13%/THC 9% showed significant improvements in MS patients over 6 months 5:
- Reduced disability progression rate (decreased EDSS scores, p=0.009) 5
- Substantial improvement in muscle spasticity (Modified Ashworth Scale, p<0.001) 5
- Notable improvement in bladder dysfunction (Post Void Residual volume, p<0.001) 5
What Cannabinoids Do NOT Help
Clinicians should counsel patients that cannabinoids are:
- Ineffective for cognitive impairment (Level A evidence) 2
- Probably ineffective for tremor (Level B/C evidence) 2, 4
- Probably ineffective for objective physician-measured spasticity in short-term studies 2, 4
Dosing Approach
When prescribing cannabinoid products for MS 3:
- Start with the lowest available dose and titrate gradually
- Target dose range: 20-40 mg THC daily in divided doses based on clinical trial data
- For nabiximols spray: titrate over several days to weeks based on symptom response and tolerability
- Monitor response over 6-8 weeks before determining efficacy
Safety Considerations and Adverse Events
Cannabinoids may increase treatment discontinuation due to adverse events (39 more people per 1000 discontinue compared to placebo) 4. Specific risks include:
- Nervous system disorders: Cannabinoids may increase dizziness, sedation, and other CNS effects (odds ratio 2.61) 4
- Psychiatric disorders: Increased risk of psychiatric symptoms (odds ratio 1.94) 4
- Cardiovascular risks: Growing evidence links cannabis to myocardial infarction, hypertension, heart failure, and stroke 3
- Psychosis risk: Cannabis use increases risk of psychosis and schizophrenia in at-risk individuals 3
- Cannabinoid hyperemesis syndrome: A recognized adverse effect of chronic cannabis use 3
Critical Caveats for Older Adults
Exercise particular caution in older MS patients 1:
- Acute cannabis toxicity in older adults may cause sedation, obtundation, and myocardial ischemia or infarction 1
- Cannabis-related emergency department visits have increased among older adults 1
- Consider age-related cardiovascular risk factors before prescribing 3
Contraindications
Advise complete avoidance in 1:
- Pregnant or breastfeeding individuals (FDA and U.S. Surgeon General recommendation due to fetal brain development risks and premature birth)
- Patients with personal or family history of psychosis or schizophrenia
- Young adults with early-onset cannabis use (elevated risk for cannabis use disorder)
Quality Control Warning
Counsel patients about standardized versus non-standardized cannabis extracts 2:
- FDA-approved products (nabiximols in some countries, dronabinol, nabilone) have consistent dosing and quality control
- Medical marijuana products lack federal regulation and standardization
- Overall CAM quality control is limited due to non-regulation 2
Monitoring Requirements
When prescribing cannabinoids for MS 2, 4:
- Assess for cannabis use disorder symptoms (irritability, insomnia, headaches with withdrawal) 1
- Monitor for signs of misuse, particularly in patients with substance abuse history 1
- Evaluate cardiovascular status, especially in older patients
- Screen for psychiatric symptoms at each visit
- Reassess efficacy at 6-8 weeks; discontinue if no benefit
Drug Tolerance Concerns
The evidence is very uncertain about cannabinoid drug tolerance development (odds ratio 3.07, very low-certainty evidence) 4, requiring:
- Long-term monitoring for loss of efficacy
- Periodic reassessment of dose requirements
- Consideration of drug holidays if tolerance suspected