Medical Cannabis for Chronic Pain: What the Evidence and the Law Say | Research

The takeaway

A review found medical cannabis produced statistically significant but modest pain reductions (0.43-0.70 points on a 10-point scale) compared to placebo, with serious adverse events being rare but a 29% risk of developing cannabis use disorder.

Pain management clinicians, patients considering medical cannabis for chronic pain, and healthcare policy professionals.

What the researchers found

Medical cannabis reduced pain by 0.43-0.70 points on the NRS scale (0-10) versus placebo across studies. Serious adverse events were rare. Common side effects included dizziness, drowsiness, dry mouth, and nausea. The risk of cannabis use disorder was approximately 29% per DSM-5 criteria. Absolute contraindications include unstable cardiovascular disease, psychosis, bipolar disorder, and pregnancy.

Why it matters

As medical cannabis prescriptions increase globally, pain therapists need a comprehensive understanding of what the evidence actually shows. The modest pain reduction alongside a substantial addiction risk frames a realistic benefit-risk conversation for patients.

The numbers in context

Pain reduction vs. placebo: -0.43 to -0.70 on NRS (0-10). Cannabis use disorder risk: ~29% (DSM-5). Rare serious adverse events. Common AEs: dizziness, tiredness, drowsiness, nausea, dry mouth, diarrhea, constipation, euphoria.

How the study worked

Narrative review of available literature on medical cannabis for chronic pain, covering efficacy, safety, contraindications, drug interactions, dosing, and medico-legal considerations in the Italian regulatory context.

What this study cannot tell us

Narrative review without systematic methodology. The 29% CUD risk figure may overestimate risk in medically supervised use. Medico-legal considerations are specific to Italian law. Pain reduction averages mask individual variation in response. Does not cover all cannabis formulations or routes.

How to read the evidence

Comprehensive clinical review with specific quantitative data from the literature, but narrative format without systematic search methodology.

When this study was published

Published 2025.

The bigger picture

The gap between patient expectations and evidence-based outcomes is wide in medical cannabis for pain. A mean pain reduction of less than one point on a 10-point scale is statistically significant but clinically modest. Combined with the 29% CUD risk, this underscores the need for realistic patient counseling.

Questions still open

Whether specific patient subgroups show much larger pain reductions than the average
How the CUD risk in supervised medical cannabis compares to recreational use patterns

Common questions

Is a 0.43-0.70 point pain reduction meaningful?

It is statistically significant but clinically modest. For context, a 2-point reduction on a 10-point scale is generally considered the minimum clinically important difference. However, some individual patients may experience much larger benefits than the average suggests.

What does the 29% cannabis use disorder risk mean?

According to DSM-5 criteria, about 29% of cannabis users may meet criteria for cannabis use disorder, which includes symptoms like tolerance, withdrawal, and continued use despite negative consequences. This figure comes from general population data and may differ in medically supervised contexts.

Read the original research

Medical cannabis for chronic pain management: questions and answers between clinical and medico-legal issues.

Clinical and experimental rheumatology, 43(6), 1128-1135

View on PubMed ↗Publisher’s paper ↗

Citation

Schweiger, Vittorio; Ganz, Barbara; Martini, Alvise; Sarzi-Puttini, Piercarlo; Bazzichi, Laura; Bonora, Eleonora; Vendramin, Patrizia; Nizzero, Marta; Zamboni, Lorenzo; Polati, Luca; Lugoboni, Fabio; Raniero, Dario; Polati, Enrico; Del Balzo, Giovanna. (2025). Medical cannabis for chronic pain management: questions and answers between clinical and medico-legal issues.. Clinical and experimental rheumatology, 43(6), 1128-1135. https://doi.org/10.55563/clinexprheumatol/o23y55