SynthesisBMJ open2021
Opioid-sparing effects of medical cannabis or cannabinoids for chronic pain: a systematic review and meta-analysis of randomised and observational studies.
Synthesis in BMJ open, 2021. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 39 papers, 5 of them syntheses that pooled it.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
39 citing papers in PubMed, 5 syntheses or guidelines pooled it, 105 citations in OpenAlex.
- Cannabinoids and opioid consumption in cancer pain: a systematic review and meta-analysis.Supportive care in cancer : official journal of the Multinational Association of Supportive Care in Cancer · 2026Pooled it
- Pooled it
- Balancing risks and benefits of cannabis use: umbrella review of meta-analyses of randomised controlled trials and observational studies.BMJ (Clinical research ed.) · 2023Pooled it
- Long-term and serious harms of medical cannabis and cannabinoids for chronic pain: a systematic review of non-randomised studies.BMJ open · 2022Pooled it
- Opioid-sparing effect of cannabinoids for analgesia: an updated systematic review and meta-analysis of preclinical and clinical studies.Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology · 2022Pooled it
- Trial
- Trial
- Within-subject, double-blind, randomized, placebo-controlled evaluation of combining the cannabinoid dronabinol and the opioid hydromorphone in adults with chronic pain.Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology · 2023Trial
- Ten-year outcomes of medical cannabis for chronic low back pain: opioid reduction, pain relief, and functional improvement in 1,000 patients.European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society · 2026Article
- Does Cannabinoid Use Reduce Opioid Utilization Among Patients with Gastrointestinal Cancer? Evidence from Epic COSMOS.Cancers · 2026Article
- A Scoping Systematic Review of Cannabis Use in Endometriosis.The Australian & New Zealand journal of obstetrics & gynaecology · 2026Article
- Medical cannabis authorization and opioid milligram equivalents over time in patients with chronic pain: a retrospective analysis.Pain medicine (Malden, Mass.) · 2026Article
- Cannabis Use and Risk of Chronic Rhinosinusitis and Sinus Surgery.Laryngoscope investigative otolaryngology · 2025Article
- Cannabis Use and Analgesic Prescribing in UK Primary Care: A Retrospective Cohort Study of Patients with Osteoarthritis.Medicines (Basel, Switzerland) · 2025Article
- Opioid reduction in patients with chronic non-cancer pain undergoing treatment with medicinal cannabis.Pain management · 2025Article
- Cannabinoids in Chronic Pain Management: A Review of the History, Efficacy, Applications, and Risks.Biomedicines · 2025Review
- Substituting Medical Cannabis for Medications Among Patients with Rheumatic Conditions in the United States and Canada.ACR open rheumatology · 2024Article
- Clinical Benefits and Safety of Medical Cannabis Products: A Narrative Review on Natural Extracts.Pain and therapy · 2024Review
- Effect of cannabis use history on postoperative opioid utilization in lumbar fusion patients: an American retrospective study.Asian spine journal · 2024Article
- Interactions Between Endocannabinoid and Endogenous Opioid Systems Prospectively Influence Postoperative Opioid Use in Pregnant Patients Undergoing Cesarean Delivery.The journal of pain · 2024Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
12 authors at 3 institutions in 2 countries.
Funding
No grant is acknowledged in the PubMed record.
Abstract
objectiveTo assess the efficacy and harms of adding medical cannabis to prescription opioids among people living with chronic pain.
designSystematic review. DATA SOURCES: CENTRAL, EMBASE and MEDLINE. MAIN OUTCOMES AND MEASURES: Opioid dose reduction, pain relief, sleep disturbance, physical and emotional functioning and adverse events. STUDY SELECTION CRITERIA AND
methodsWe included studies that enrolled patients with chronic pain receiving prescription opioids and explored the impact of adding medical cannabis. We used Grading of Recommendations Assessment, Development and Evaluation to assess the certainty of evidence for each outcome.
resultsEligible studies included five randomised trials (all enrolling chronic cancer-pain patients) and 12 observational studies. All randomised trials instructed participants to maintain their opioid dose, which resulted in a very low certainty evidence that adding cannabis has little or no impact on opioid use (weighted mean difference (WMD) -3.4 milligram morphine equivalent (MME); 95% CI (CI) -12.7 to 5.8). Randomised trials provided high certainty evidence that cannabis addition had little or no effect on pain relief (WMD -0.18 cm; 95% CI -0.38 to 0.02; on a 10 cm Visual Analogue Scale (VAS) for pain) or sleep disturbance (WMD -0.22 cm; 95% CI -0.4 to -0.06; on a 10 cm VAS for sleep disturbance; minimally important difference is 1 cm) among chronic cancer pain patients. Addition of cannabis likely increases nausea (relative risk (RR) 1.43; 95% CI 1.04 to 1.96; risk difference (RD) 4%, 95% CI 0% to 7%) and vomiting (RR 1.5; 95% CI 1.01 to 2.24; RD 3%; 95% CI 0% to 6%) (both moderate certainty) and may have no effect on constipation (RR 0.85; 95% CI 0.54 to 1.35; RD -1%; 95% CI -4% to 2%) (low certainty). Eight observational studies provided very low certainty evidence that adding cannabis reduced opioid use (WMD -22.5 MME; 95% CI -43.06 to -1.97).
conclusionOpioid-sparing effects of medical cannabis for chronic pain remain uncertain due to very low certainty evidence.
Indexed as
Identifiers
What OpenQuestion holds
Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.