Osteoarthritis patients with recorded cannabis use were prescribed more opioids, not fewer | Research

The takeaway

UK primary care patients with osteoarthritis who had cannabis use in their records were twice as likely to be prescribed opioids and had higher rates of all analgesic prescriptions compared to matched non-users.

Pain management clinicians, researchers studying cannabis-opioid interactions, and policy makers evaluating cannabis substitution claims.

Cannabis-exposed patients 2.06x more likely to receive opioid prescriptions

What the researchers found

Cannabis-exposed osteoarthritis patients had a 2.06x higher hazard of being prescribed opioids compared to matched unexposed patients. They were also more likely to receive prescriptions for other analgesics and had higher mortality.

Why it matters

Some advocates claim cannabis reduces opioid use, but this real-world UK data shows the opposite association. However, the finding likely reflects confounding: patients with coded cannabis use may have more complex pain or socioeconomic disadvantage.

The numbers in context

662 exposed matched to 1,319 unexposed. Opioid prescribing HR: 2.06 (95% CI 1.74-2.43). Cannabis-exposed group also had higher mortality. Cannabis use recording is rare relative to actual prevalence in the general population.

How the study worked

Population-based retrospective cohort using UK Clinical Practice Research Datalink (1995-2023), matching 662 opioid-naive osteoarthritis patients with coded cannabis exposure to 1,319 unexposed patients by age, sex, smoking status, and health authority.

What this study cannot tell us

Cannabis exposure was based on medical record coding, which likely captures problematic use or use disclosed during clinical encounters rather than typical recreational use. Substantial confounding by socioeconomic status and severity is likely.

How to read the evidence

Large database study with appropriate matching, but cannabis exposure capture is highly selective and confounding by indication and socioeconomic status is likely substantial.

When this study was published

Published in 2025, data 1995-2023.

The bigger picture

The 'cannabis as opioid substitute' narrative is complicated by real-world data showing cannabis users often have higher, not lower, analgesic needs. Whether this reflects the population captured in medical records or a true association remains unclear.

Questions still open

Does recorded cannabis use in medical records represent a different population than typical cannabis users? Would prospective studies of intentional cannabis-for-pain substitution show different opioid patterns?

Common questions

Does cannabis use reduce the need for opioid painkillers?

This UK study found the opposite: osteoarthritis patients with cannabis use in their records were prescribed more opioids, not fewer. However, those with recorded cannabis use may represent a population with more complex pain needs.

Why might cannabis users need more pain medication?

The researchers caution that patients whose cannabis use appears in medical records may have more severe conditions, higher pain levels, or socioeconomic disadvantage. The recorded cannabis use is rare and likely does not represent typical users.

Read the original research

Cannabis Use and Analgesic Prescribing in UK Primary Care: A Retrospective Cohort Study of Patients with Osteoarthritis.

Medicines (Basel, Switzerland), 12(4)

View on PubMed ↗Publisher’s paper ↗

Citation

Erridge, Simon; Chandan, Joht Singh; Gokhale, Krishna M; Billinghurst, Christian; Sodergren, Mikael H. (2025). Cannabis Use and Analgesic Prescribing in UK Primary Care: A Retrospective Cohort Study of Patients with Osteoarthritis.. Medicines (Basel, Switzerland), 12(4). https://doi.org/10.3390/medicines12040027