Medical cannabis improved pain, anxiety, sleep, and quality of life in complex regional pain syndrome patients | Research

The takeaway

In a UK registry of 64 CRPS patients prescribed cannabis-based medicines, pain severity, anxiety, sleep quality, and overall quality of life all improved significantly over 6 months.

Pain specialists treating CRPS, patients with complex regional pain syndrome, and researchers designing cannabis trials for chronic pain conditions.

Pain, anxiety, sleep, and quality of life all improved significantly over 6 months

What the researchers found

Pain severity on the Brief Pain Inventory improved from 6.69 at baseline to 5.85 at 1 month and 6.05 at 6 months. Improvements were also seen in the McGill Pain Questionnaire, pain VAS, anxiety symptoms, sleep quality, and general health-related quality of life at multiple time points.

Why it matters

CRPS is notoriously difficult to treat and causes severe, persistent pain. This is the first study examining cannabis-based medicines specifically for CRPS, providing initial data for a condition with few effective treatments.

The numbers in context

64 patients. Pain severity BPI: 6.69 baseline to 5.85 at 1 month (p<0.05). McGill Pain, VAS, anxiety, sleep, and quality of life all improved (p<0.05). 5 patients (7.8%) reported adverse events. 50 adverse events (78.1%) recorded total.

How the study worked

Case series from the UK Medical Cannabis Registry tracking patient-reported outcomes over 6 months in 64 CRPS patients, with adverse events graded using CTCAE v4.0.

What this study cannot tell us

No control group or blinding means improvement could reflect placebo response, natural disease fluctuation, or concurrent treatments. Registry data may have selection bias. Pain improvement, while statistically significant, was modest in absolute terms.

How to read the evidence

Uncontrolled case series provides initial observational data. Without a comparison group, placebo effects and natural variation cannot be excluded.

When this study was published

Published in 2025.

The bigger picture

CRPS affects an estimated 200,000 people in the US alone, with limited treatment options and high rates of disability. If cannabis-based medicines prove effective in controlled trials, they could fill a significant gap in CRPS management.

Questions still open

Would a randomized controlled trial confirm these improvements? Is the modest absolute pain reduction clinically meaningful for CRPS patients?

Common questions

Can medical cannabis help with complex regional pain syndrome?

This UK registry study of 64 patients found improvements in pain, anxiety, sleep, and quality of life over 6 months. However, without a control group, these improvements could reflect other factors.

What side effects did CRPS patients experience with medical cannabis?

7.8% of patients reported adverse events. The study noted 50 total adverse events among the group. The majority of effects were not severe enough to warrant treatment discontinuation.

Read the original research

UK Medical Cannabis Registry: A Clinical Outcomes Analysis for Complex Regional Pain Syndrome.

Brain and behavior, 15(9), e70823

View on PubMed ↗Publisher’s paper ↗

Citation

Evans, Lilia; Erridge, Simon; Varadpande, Madhur; Aggarwal, Arushika; Cowley, Isaac; Clarke, Evonne; McLachlan, Katy; Coomber, Ross; Rucker, James J; Platt, Michael; Sodergren, Mikael H. (2025). UK Medical Cannabis Registry: A Clinical Outcomes Analysis for Complex Regional Pain Syndrome.. Brain and behavior, 15(9), e70823. https://doi.org/10.1002/brb3.70823