#200 Harms of Medical Cannabinoids: Up in Smoke!
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- Total adverse events: Four meta-analyses with 3-29 Randomized Controlled Trials (RCTs), 666-3,714 patients.1-5
- Range1-3 from relative risk 1.18 to odds ratio (OR) 3.03.
- Percent of patients: 4,5 79-92% cannabinoid versus 56-78% placebo.
- Number Needed to Harm (NNH)=5-8.
- Serious adverse events: Three meta-analyses with 11-34 RCTs, 1,568-3,248 patients.1,2,6
- Two non-statistically significant.1,2
- Other OR 1.41 (1.04-1.92), absolute numbers not provided.6
- Stopped due to adverse events: Seven meta-analyses (2-24 RCTs), 276-2,755 patients.2,5-10
- Range from2,7,8 OR 2.94 to Risk Ratio 6.85.
- Actual events:5-9 7-14% cannabinoid versus 1-5% placebo, NNH=8-22.
- One of the seven meta-analyses was not statistically significant.10
- Specific adverse events versus placebo:
- Predictable effects: Sedation8 NNH=5, feeling high7,8 NNH=2-4, euphoria7,8 NNH=9.
- Common: Visual blurring/hallucination11 NNH=3, dizziness2,5,8,11 NNH=5, speech disorders11 NNH=5, ataxia/muscle twitching11 NNH=6, disconnected thought11 NNH=7, dysphoria8 NNH=8, hypotension8 NNH=8, impaired memory11 NNH=12, disorientation11 NNH=15.
- Nausea (OR 2.1) and vomiting (OR 1.7) increased, NNH unavailable.2
- Other: Hallucination8 NNH=17, paranoia8 NNH=20.
- Versus other agents like prochlorperazine, cannabinoids also increased adverse events:7 Example sedation (NNH=7) and dizziness (NNH=3).
- Adverse events rates varied little between different cannabinoid products (example nabiximol, nabilone, dronabinol, inhaled marijuana, etc.):2 NNH=4-7.
- See Tools for Practice #199 and #201 for potential benefits.
- Many studies enrolled patients with a history of medical or recreational cannabinoid use.11,12 Regular users will:
- Be more tolerant of cannabinoids and less likely to report adverse events.
- Recognize if randomized to cannabinoids or placebo (up to 89% of the time).12