My knee-jerk response to this question is another question: if you are sick enough to require antibiotics, why are you out partying/ drinking alcohol in the first place? Stay in bed and recover!

But for those who just can’t miss out on the party, I have a detailed answer. Alcohol consumption decreases your immune system’s ability to fight infection by inhibiting the proliferation of white blood cells (cells that attack an infection). That’s one good reason to stay away from alcohol when on antibiotics!

Some people have asked me: will I pass out if I drink alcohol while on antibiotics? The short answer is: with most antibiotics, probably not. But you may have some unpleasant reactions depending on which antibiotics you are taking.

A few antibiotics — such as Metronidazole (brand-name Flagyl), Tinidazole (Tindamax) and Trimethoprim-sulfamethoxazole (Bactrim) — should not be mixed with alcohol as the combination can result in side effects such as flushing, headache, nausea and vomiting, rapid heart rate, and shortness of breath. Bactrim is commonly used to treat female urinary tract infections; Flagyl is commonly used to treat diarrhea caused by Giardia, a parasite one may pick up while camping, as well as Trichomoniasis, a sexually transmitted disease. Tindamax is an alternative to Flagyl, and can be used to treat Giardia and Trichomoniasis too.

Other common antibiotics, such as Azithromycin (the “Z-Pak” used for community-acquired pneumonia, bronchitis, and Chlamydial infections), Nitrofurantoin for urinary tract infections, and Amoxicillin, used for ear infections and bladder infections, do not seem to have dangerous reactions with alcohol. But, again, using alcohol when on these antibiotics will diminish your immune system’s response and therefore may lead to a longer time-to-recovery.

Take home message of the day: Avoid alcohol when on antibiotics. The bar will still be there when you’re feeling better.