(HealthDay News) — Cannabis should not be used to prevent postoperative nausea and vomiting (PONV) because of unacceptable side effects and low effectiveness, according to a study published online in Anesthesia & Analgesia.

Maren Kleine-Brueggeney, M.D., from the University of Bern in Switzerland, and colleagues randomized 40 patients at high risk for PONV to either 0.125 mg/kg intravenous tetrahydrocannabinol (THC) or placebo at the end of surgery before emergence from anesthesia.

The researchers found that the relative risk reduction of overall PONV in the THC group was 12%, lower than the clinically significant 25% relative risk reduction demonstrated by other drugs used for PONV prophylaxis. After the researchers adjusted for anesthesia time, the effect of treatment had an odds ratio of 0.97 (P = 0.97). There were clinically relevant psychotropic THC side effects, mainly consisting of sedation and confusion not related to the effects of anesthesia. The study was discontinued because of THC’s inefficacy and the clinically unacceptable side effects.

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“Because of an unacceptable side effect profile and uncertain antiemetic effects, IV THC administered at the end of surgery before emergence from anesthesia cannot be recommended for the prevention of PONV in high-risk patients,” the authors write.


  1. Kleine-Brueggeney, M; Greif, R; Brenneisen, R; Urwyler, N; Stueber, F; and Theiler, LG; Anesthesia & Analgesia, September 30, 2015; doi: 10.1213/ANE.0000000000000877.