Drug interactions between black cohosh and Flagyl

GENERALLY AVOID: Due to a potentially high alcohol content, tincture formulations of black cohosh may theoretically produce a disulfiram-like reaction when coadministered with drugs that may be capable of inhibiting aldehyde dehydrogenase (ALDH) such as metronidazole, furazolidone, and cephalosporins with an N-methylthiotetrazole (NMTT) side chain that structurally resembles disulfiram. Following ingestion of alcohol, inhibition of ALDH results in increased concentration of acetaldehyde, the accumulation of which produces an unpleasant physiologic response referred to as the "disulfiram reaction". Symptoms include flushing, throbbing in head and neck, throbbing headache, respiratory difficulty, nausea, vomiting, sweating, thirst, chest pain, palpitation, dyspnea, hyperventilation, tachycardia, hypotension, syncope, weakness, vertigo, blurred vision, and confusion. Severe reactions may result in respiratory depression, cardiovascular collapse, arrhythmias, myocardial infarction, acute congestive heart failure, unconsciousness, convulsions, and death. The interaction is well established for disulfiram. However, data for other potential ALDH inhibitors such as metronidazole and cephalosporins are limited and conflicting.

MANAGEMENT: Until more information is available, the use of black cohosh tinctures with metronidazole (including vaginal formulations), furazolidone, and certain cephalosporins should be avoided if possible. Given its structural similarities to metronidazole, the same precaution may be applicable to tinidazole, although clinical data are lacking.