Antibiotic interactions: Answers to 4 common questions
Which antibiotics should you consider when a patient is taking warfarin? Which ones are associated with drug-induced, prolonged QT intervals? Read on.
4. Should patients avoid alcohol while taking metronidazole?
Probably not.
Warning patients against drinking alcohol while taking metronidazole has been a common practice for years. The mechanism for this theorized interaction was thought to be similar to the interaction between disulfiram and ethanol.34 Disulfiram inhibits hepatic aldehyde dehydrogenase (ALDH) when combined with alcohol, which leads to increased levels of acetaldehyde in the blood and symptoms of flushing, palpitations, nausea, vomiting, headache, and visual disturbances.35 However, multiple studies using rats have found that metronidazole does not inhibit ALDH or increase acetaldehyde concentrations like disulfiram does.34
A 2000 review article discussed 6 cases involving serious metronidazole-ethanol interactions. Ethanol alone was found to explain the reaction in 2 of the cases, and the remaining 4 could be linked to the use of other drugs or disease states.35 A 2002 Finnish study found no statistically significant differences in objective or subjective signs of a disulfiram-like interaction.34 When considering the symptoms associated with the interaction, it is important to remember that many of the symptoms can result from metronidazole therapy alone, regardless of whether other medications or alcohol are used.35
THE BOTTOM LINE Researchers have failed to identify a clinically significant interaction between metronidazole and alcohol. Avoiding alcohol while taking metronidazole does not appear to be necessary.
CORRESPONDENCE
Mary Onysko, PharmD, BCPS, University of Wyoming, School of Pharmacy Health Sciences Center, Room 292, 1000 E. University Avenue, Laramie, WY 82071; monysko@uwyo.edu.
