Adding Cannabis to Oxycodone for Fibromyalgia Offered No Advantage and Was Poorly Tolerated | Research

The takeaway

In a randomized trial of fibromyalgia patients, combining cannabis with oxycodone reduced opioid tablet intake by 35% but offered no advantage in pain relief or side effects, and one-third of cannabis users dropped out due to adverse effects.

Pain specialists, fibromyalgia patients, and opioid prescribers

31% of cannabis users dropped out due to adverse effects within 2-3 weeks

What the researchers found

The combination of cannabis and oxycodone reduced opioid tablet consumption by 35% (p=0.02) but did not reduce adverse effects or improve pain relief compared to either treatment alone. One-third (31%) of cannabis-treated patients withdrew within 2-3 weeks due to severity of adverse effects, compared to 13% in the oxycodone-only group. Only 50% of patients experienced any pain reduction, and only 20% had meaningful (2+ point) relief.

Why it matters

This is one of the first RCTs to directly test the popular belief that cannabis can reduce opioid use in chronic pain. While it did reduce pill consumption, the overall drug burden was higher in the combination group, and cannabis was poorly tolerated.

The numbers in context

81 patients randomized. Dropouts: 13% oxycodone, 31% cannabis groups. No difference in adverse event scores (p=0.70). Combination reduced opioid intake by 35% (p=0.02). 50% had any pain reduction. 20% had meaningful reduction. Cannabis: 6.3% THC, 8% CBD.

How the study worked

Open-label randomized trial of fibromyalgia patients: 23 received oxycodone alone (5mg tablets, max 4x/day), 29 received inhaled cannabis (150mg, 6.3% THC/8% CBD, max 3 sessions/day), and 29 received the combination, for 6 weeks. Primary endpoint was composite adverse event score.

What this study cannot tell us

Open-label design introduces expectancy effects. Small sample sizes per group. Six-week duration may be too short for full adaptation. The specific cannabis formulation (higher CBD than THC) may have contributed to the tolerability issues.

How to read the evidence

Randomized trial with appropriate comparisons, but open-label design and small sample sizes limit conclusions.

When this study was published

2024 study

The bigger picture

The cannabis-opioid substitution narrative is popular but oversimplified. This trial suggests that while cannabis may reduce the amount of opioids taken, it does not reduce overall drug burden or side effects, and is itself poorly tolerated by a significant minority of pain patients.

Questions still open

Would a different THC:CBD ratio be better tolerated? Is the 35% opioid reduction clinically meaningful if overall drug burden increases? Would longer treatment allow adaptation to cannabis side effects?

Common questions

Can cannabis replace opioids for fibromyalgia pain?

Not based on this trial. While combining cannabis with oxycodone reduced opioid pill consumption by 35%, it did not improve pain relief or reduce side effects, and one-third of cannabis users dropped out due to adverse effects.

Was cannabis well tolerated for fibromyalgia?

No. 31% of patients using cannabis (alone or combined) withdrew within 2-3 weeks due to severity of adverse effects, compared to only 13% in the opioid-only group.

Read the original research

Cannabis combined with oxycodone for pain relief in fibromyalgia pain: a randomized clinical self-titration trial with focus on adverse events.

Frontiers in pain research (Lausanne, Switzerland), 5, 1497111

View on PubMed ↗Publisher’s paper ↗

Citation

van Dam, Cornelis Jan; Kramers, Cornelis; Schellekens, Arnt; Bouvy, Marcel; van Dorp, Eveline; Kowal, Mikael A; Olofsen, Erik; Dahan, Albert; Niesters, Marieke; van Velzen, Monique. (2024). Cannabis combined with oxycodone for pain relief in fibromyalgia pain: a randomized clinical self-titration trial with focus on adverse events.. Frontiers in pain research (Lausanne, Switzerland), 5, 1497111. https://doi.org/10.3389/fpain.2024.1497111