THC-rich cannabis oil significantly improved fibromyalgia symptoms in a small RCT
In a small randomized trial of 17 women with fibromyalgia, THC-rich cannabis oil significantly reduced overall symptom scores compared to placebo, with improvements in feeling good, pain, ability to work, and fatigue.
Quick Facts
What This Study Found
After 8 weeks, the cannabis group showed significant FIQ score improvement vs. placebo (p = 0.005) and vs. baseline (p < 0.001). Specific improvements were seen in "feel good," "pain," "do work," and "fatigue" scores. The placebo group only improved on the "depression" score. No intolerable adverse effects occurred.
Key Numbers
17 women; 8-week trial; THC oil: 24.44 mg/mL THC, 0.51 mg/mL CBD. Starting dose: ~1.22 mg THC/day. FIQ score significantly improved in cannabis group vs. placebo (p = 0.005) and vs. baseline (p < 0.001).
How They Did This
Double-blind, randomized, placebo-controlled trial. 17 women with fibromyalgia from a low-income neighborhood in Florianopolis, Brazil. THC-rich cannabis oil (24.44 mg/mL THC, 0.51 mg/mL CBD) starting at 1 drop/day with dose increases. Fibromyalgia Impact Questionnaire at baseline and 5 visits over 8 weeks.
Why This Research Matters
Fibromyalgia has limited effective treatments. This is one of the few RCTs testing THC-dominant cannabis oil specifically for fibromyalgia, showing significant improvement across multiple symptom domains.
The Bigger Picture
This adds to emerging evidence that cannabinoids may help fibromyalgia, though the small sample means results should be interpreted cautiously until larger trials confirm these findings.
What This Study Doesn't Tell Us
Very small sample (17 participants); 8-week duration; specific population (low-income Brazilian women) may limit generalizability; no long-term follow-up; low starting doses.
Questions This Raises
- ?Would similar results appear in larger, longer trials?
- ?Is THC-dominant or CBD-dominant oil more effective for fibromyalgia?
- ?How do socioeconomic factors interact with treatment response?
Trust & Context
- Key Stat:
- Cannabis group FIQ scores improved significantly vs. placebo (p = 0.005)
- Evidence Grade:
- Randomized, double-blind, placebo-controlled, but very small sample size (n = 17).
- Study Age:
- Published in 2020.
- Original Title:
- Ingestion of a THC-Rich Cannabis Oil in People with Fibromyalgia: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial.
- Published In:
- Pain medicine (Malden, Mass.), 21(10), 2212-2218 (2020)
- Database ID:
- RTHC-02462
Evidence Hierarchy
Participants are randomly assigned to treatment or placebo groups to test cause and effect.
What do these levels mean? →Frequently Asked Questions
What was the starting dose of THC?
Patients started with approximately 1.22 mg THC per day (one drop), with subsequent increases based on symptoms. This is a very low starting dose, suggesting even small amounts of THC may provide benefit for fibromyalgia.
Were there significant side effects?
No intolerable adverse effects were reported during the 8-week trial. The researchers describe the treatment as well-tolerated, though the small sample limits the ability to detect rare side effects.
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Cite This Study
https://rethinkthc.com/research/RTHC-02462APA
Chaves, Carolina; Bittencourt, Paulo Cesar T; Pelegrini, Andreia. (2020). Ingestion of a THC-Rich Cannabis Oil in People with Fibromyalgia: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial.. Pain medicine (Malden, Mass.), 21(10), 2212-2218. https://doi.org/10.1093/pm/pnaa303
MLA
Chaves, Carolina, et al. "Ingestion of a THC-Rich Cannabis Oil in People with Fibromyalgia: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial.." Pain medicine (Malden, 2020. https://doi.org/10.1093/pm/pnaa303
RethinkTHC
RethinkTHC Research Database. "Ingestion of a THC-Rich Cannabis Oil in People with Fibromya..." RTHC-02462. Retrieved from https://rethinkthc.com/research/chaves-2020-ingestion-of-a-thcrich
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.