A new analysis of the British Medical Cannabis Registry tracked 3,744 chronic pain patients over up to two years. On average, pain, sleep, anxiety, and quality of life all improved. But beyond the averages lies a more revealing finding: whether someone benefited was more strongly tied to baseline sleep and anxiety than to the product or dose prescribed.
📑 Inhaltsverzeichnis
The work was published in October 2026 in the Journal of Clinical Pharmacology. Lead author Simon Erridge and the research group around Mikael H. Sodergren at Imperial College London have been analyzing the UK Medical Cannabis Registry for years. The same database also yielded the analysis we reported on regarding two years of cannabis therapy for endometriosis.
Chronic Pain and Medical Cannabis: Study Design
Participants were registry members for whom chronic pain was the primary indication for cannabis-based medicines. Using standardized questionnaires at baseline and at intervals up to 24 months, researchers measured: pain severity and daily impairment via the Brief Pain Inventory, health-related quality of life via the EQ-5D-5L, anxiety via the GAD-7, and sleep quality via a single-item scale.
The methodological innovation comes in the second step. Rather than just reporting averages, the authors used k-means clustering to group individual pain trajectories by pattern. Regression analysis then identified which baseline characteristics predicted membership in each trajectory type.
Results: Average Improvement Across Five Distinct Patterns
All measured endpoints showed statistically significant improvement from baseline to 24 months. Effect sizes were d = 0.57 for pain severity, 0.59 for pain-related impairment, and 0.76 for quality of life index—all moderate effects. More than half of patients achieved clinically relevant improvement on every pain measure at the 24-month mark. According to a study summary, average pain severity in the group with 24-month data declined from 5.86 to 4.55 on a 0–10 scale.
Cluster analysis identified five distinct trajectory types. All ended below their starting levels, but the magnitude and pattern of change differed markedly, ranging from substantial to modest improvements. Adverse effects were reported by 538 patients—14.37 percent—mostly mild to moderate in severity.
Sleep and Anxiety Matter More Than Dose or Product
The most clinically relevant finding concerns prediction. Treatment response was more strongly linked to baseline sleep quality, the degree of baseline anxiety, and the specific pain indication than to product and dose characteristics. This has practical implications: the search for the „right strain“ or „perfect THC content“ explains less about outcomes than many practitioners assume. Sleep disturbances and anxiety should be thoroughly assessed before selecting a specific product.
Similar registries now exist in several countries. A Minnesota registry on cannabis for autism also showed that only a portion of patients benefit durably. Controlled trials remain rare; notable exceptions include the Charité pilot study on endometriosis pain.
Limitations of the Registry Study and Context for Germany
A registry study has no control group. Part of the improvement may be due to placebo effects, to the natural fluctuation of chronic pain, or to other therapies. Then there is attrition: not all 3,744 patients were still providing data after two years, and those who drop out often responded less well. Almost three quarters of the participants had also used cannabis before. The results therefore show an association, not proof of efficacy.
The study is nevertheless relevant for Germany. Chronic pain is by far the most common indication for medical cannabis here. In addition, with Exilby there has been, since this year, an approved cannabis medicine for chronic back pain. Those who select patients get a practical takeaway from the British analysis: not everyone responds in the same way, and the baseline situation predicts more than the label does.
Frequently Asked Questions
How many patients were included in the British registry study?
The analysis included 3,744 patients from the UK Medical Cannabis Registry whose primary indication was chronic pain. They were followed for up to 24 months after treatment initiation.
How effective is medical cannabis for chronic pain?
On average, pain severity and functional impairment improved with moderate effect sizes, with more than half achieving clinically significant improvement. Without a control group, however, we cannot determine what proportion of improvement is attributable to cannabis itself.
Which factors predict treatment response?
The strongest predictors of outcome were baseline sleep quality and anxiety levels, along with the specific pain indication. Product characteristics and dose played a secondary role.
How common were adverse effects?
Adverse effects were reported by 538 patients—14.37 percent—with most rated as mild to moderate in severity.
Nutzt du Cannabis gegen chronische Schmerzen?
Source: Erridge S, Datta A, Mukherjee A et al.: Pain Severity Trajectories and Patient Profiles in Chronic Pain Patients Treated with Cannabis-Based Medicinal Products: A k-Means Clustering Analysis of the UK Medical Cannabis Registry. The Journal of Clinical Pharmacology, October 2026. DOI: 10.1002/jcph.70313
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