# Alcohol after metronidazole - how long to wait?



## mrs_ixy

Hello

Hoping someone can clarify - have been told contradicting things about when it is safe to drink alcohol after taking metronidazole. I am going away at the weekend and after all I have been through (mmc, erpc, emergency admission to hospital with blood clots 4 days later!) I would really like a drink. I had 400mg three times a day and took my last tablet at 9.30pm on Bank Holiday Monday.

NHS Direct said wait 48 hours. The pharmacist at the hospital said 3 days. 

So would it be safe to drink on Thursday night or should I wait until Friday?

Thanks if you can help! I also took cefalexin 500mg 3 times a day at the same time but there were no warnings about alcohol with this one.

I don't know if it is relevant but I did not have an infection (thankfully) - this was preventative.


----------



## Mistletoe (Holly)

The summary of product characteristics specifies 48 hours.

The longest half life (time it takes for concentration in blood to drop by half)  in studies recorded is about 12 hours (8.5 hours plus or minus 2.9 hours) and we usually say 5 half lives for a drug to be at a minimal concentration, so 3 days is probably safer.

If you do drink with metronidazole you can get a nasty reaction with fast heart rate, nausea, vomiting, difficulty in breathing etc. as it blocks the proper break down of the alcohol letting a poisonous metabolite build up.

Thursday night will be 72 hours after last dose so I think it should be ok.


----------

