Single cannabis inhalation showed limited pain relief in fibromyalgia patients
In a rigorous crossover trial of 20 fibromyalgia patients, no cannabis variety outperformed placebo on spontaneous or electrical pain, though THC-containing varieties increased pressure pain thresholds and the THC+CBD combination showed more patients with 30% pain reduction.
Quick Facts
What This Study Found
None of the four treatments (high-THC, THC+CBD, high-CBD, placebo) had greater effect than placebo on spontaneous or electrical pain. However, THC-containing varieties significantly increased pressure pain threshold. More patients receiving THC+CBD (Bediol) showed 30% pain reduction compared to placebo (90% vs 55%). CBD inhalation increased THC plasma concentrations but diminished THC-induced analgesic effects, suggesting pharmacokinetic synergy but pharmacodynamic antagonism.
Key Numbers
20 patients. Bedrocan: 22.4mg THC. Bediol: 13.4mg THC + 17.8mg CBD. Bedrolite: 18.4mg CBD. 90% vs 55% achieved 30% pain reduction (Bediol vs placebo, p=0.01). Pain scores correlated with drug high (ρ=-0.5, p<0.001).
How They Did This
Randomized placebo-controlled 4-way crossover trial with 20 fibromyalgia patients. Four varieties tested: Bedrocan (22.4mg THC), Bediol (13.4mg THC + 17.8mg CBD), Bedrolite (18.4mg CBD), and placebo. Single vapor inhalation with 3-hour monitoring.
Why This Research Matters
This is one of the few rigorous RCTs testing pharmaceutical-grade cannabis in fibromyalgia, a condition where many patients self-medicate with cannabis. The complex THC-CBD interaction findings challenge simple assumptions about cannabinoid combinations.
The Bigger Picture
The finding that CBD increased THC blood levels but reduced its pain-relieving effects complicates the popular narrative that THC and CBD work better together for all conditions.
What This Study Doesn't Tell Us
Only 20 patients. Single inhalation rather than sustained treatment. Fibromyalgia-specific results may not apply to other pain conditions. Correlation between pain relief and feeling high raises questions about whether analgesic effects are truly separate from psychoactive effects.
Questions This Raises
- ?Would repeated dosing over weeks produce different results?
- ?Does the THC-CBD antagonism for pain occur at different ratios?
- ?Is the pain relief primarily a psychoactive effect?
Trust & Context
- Key Stat:
- CBD reduced THC analgesic effects despite raising THC blood levels
- Evidence Grade:
- Well-designed crossover RCT with pharmaceutical-grade products, but very small sample and single-dose design.
- Study Age:
- 2019 clinical trial.
- Original Title:
- An experimental randomized study on the analgesic effects of pharmaceutical-grade cannabis in chronic pain patients with fibromyalgia.
- Published In:
- Pain, 160(4), 860-869 (2019)
- Authors:
- van de Donk, Tine, Niesters, Marieke(3), Kowal, Mikael A(4), Olofsen, Erik, Dahan, Albert, van Velzen, Monique
- Database ID:
- RTHC-02329
Evidence Hierarchy
Participants are randomly assigned to treatment or placebo groups to test cause and effect.
What do these levels mean? →Frequently Asked Questions
Does cannabis help fibromyalgia pain?
In this single-dose trial, no cannabis variety clearly outperformed placebo on pain measures, though more patients receiving THC+CBD reported meaningful pain reduction than placebo (90% vs 55%).
Does adding CBD to THC improve pain relief?
Surprisingly, CBD increased THC blood levels but reduced its pain-relieving effects in this study, suggesting the interaction between these cannabinoids is more complex than commonly assumed.
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Cite This Study
https://rethinkthc.com/research/RTHC-02329APA
van de Donk, Tine; Niesters, Marieke; Kowal, Mikael A; Olofsen, Erik; Dahan, Albert; van Velzen, Monique. (2019). An experimental randomized study on the analgesic effects of pharmaceutical-grade cannabis in chronic pain patients with fibromyalgia.. Pain, 160(4), 860-869. https://doi.org/10.1097/j.pain.0000000000001464
MLA
van de Donk, Tine, et al. "An experimental randomized study on the analgesic effects of pharmaceutical-grade cannabis in chronic pain patients with fibromyalgia.." Pain, 2019. https://doi.org/10.1097/j.pain.0000000000001464
RethinkTHC
RethinkTHC Research Database. "An experimental randomized study on the analgesic effects of..." RTHC-02329. Retrieved from https://rethinkthc.com/research/van-2019-an-experimental-randomized-study
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.