Why are you not allowed to consume even a small amount of alcohol when taking metronidazole?

You will regret it: Metronidazole can cause a rather unpleasant reaction from even small amounts of alcohol. Expect projectile vomiting, abdominal pain, chills and aches. Do not drink alcohol with the medication.

You'll vomit: Believe me, you'll be happy if you don't. Alcohol and Metronidazole combined will induce vomiting.

Side effects: Mixing this drug and alcohol causes unpleasant side effects. See this site for more info. http://www.nhs.uk/chq/pages/864.aspx?categoryid=73&subcategoryid=103.

It's like Antabuse (disulfiram): Metronidazole (flagyl) has a side effect where it blocks an enzyme, acetaldehyde dehydrogenase, which metabolizes alcohol. Acetaldehyde builds up in the body when you drink, causing headache, flushing, low blood pressure, dizziness, even fainting, as well as nausea and vomiting. It is potentially a very severe reaction and can be life-threatening in some people. This is like antabuse (disulfiram).