Metronidazole has a well-known interaction with alcohol. What reaction occurs?

• A. Disulfiram-like reaction (nausea, vomiting, flushing)
• B. Methanol poisoning
• C. No interaction
• D. Wine-induced sedation

Answer: (A)

Metronidazole can trigger a disulfiram-like reaction when alcohol is consumed. This happens because alcohol metabolism is disrupted at the aldehyde dehydrogenase step, causing acetaldehyde to accumulate. The buildup of acetaldehyde produces unpleasant symptoms such as nausea, vomiting, flushing, rapid heartbeat, sweating, headache, and sometimes dizziness or low blood pressure. This is a known, clinically important interaction, so patients are advised to avoid alcohol during treatment and for a short period after finishing therapy. It’s not simply alcohol poisoning from methanol, nor a mild sedative effect from wine, but a specific reaction linked to the way alcohol is metabolized when metronidazole is present.