Cookies on this website

We use cookies to ensure that we give you the best experience on our website. If you click 'Accept all cookies' we'll assume that you are happy to receive all cookies and you won't see this message again. If you click 'Reject all non-essential cookies' only necessary cookies providing core functionality such as security, network management, and accessibility will be enabled. Click 'Find out more' for information on how to change your cookie settings.

Objective. To investigate the efficacy of the H1 antihistamine promethazine against early anaphylactic reactions to antivenom. Design. Sequential randomised, double-blind, placebo controlled trial. Setting. Public hospital in a venom research institute, Sao Paulo, Brazil. Participants. 101 patients requiring antivenom treatment after being bitten by bothrops snakes. Intervention. Intramuscular injection of promethazine (25 mg for adults and 0.5/kg for children) or placebo given 15-20 min before starting intravenous infusion of antivenom. Main outcome measures. Incidence and severity of anaphylactic reaction occurring within 24 hours after antivenom. Results. Reactions occurred in 12 of 49 patients treated with promethazine (24%) and in 13 of 52 given placebo (25%); most were mild or moderate. Continuous sequential analysis indicated that the study could be interrupted at the 22nd united pair, without preference for promethazine or placebo. Conclusion. Prophylaxis with promethazine does not prevent early reactions. Patients should be observed carefully during antivenom infusion and the subsequent few hours.


Journal article


British Medical Journal

Publication Date





1451 - 1453