Bromodiphenhydramine is a histamine H1 receptor antagonist.1 It induces histamine release in isolated guinea pig lung when used at a concentration of 1 mM but completely prevents ovalbumin-induced histamine release in lungs isolated from ovalbumin-sensitized guinea pigs when used at concentrations of 100 and 200 μg/ml.2 Bromodiphenhydramine (17 mg/kg) inhibits formalin-induced paw edema in rats.1 It increases survival in a mouse model of systemic S. typhimurium infection when administered at doses of 1.5 and 3 mg/kg.3

|1. Ahmadi, A., Khalili, M., Nafarie, A., et al. Synthesis and anti-inflammatory effects of new piperazine and ethanolamine derivatives of H1-antihistaminic drugs. Mini Rev. Med. Chem. 12(12), 1282-1292 (2012).|2. Mota, I., and Da Silva, W.D. The anti-anaphylactic and histamine-releasing properties of the antihistamines. Their effect on the mast cells. Br. J. Pharmacol. Chemother. 15(3), 396-404 (1960).|3. Dastidar, S.G., Saha, P.K., Sanyamat, B., et al. Antibacterial activity of ambodryl and benadryl. J. Appl. Bacteriol. 41(2), 209-214 (1976).