Metronidazole
"Periodically on Flagyl bc of crohns and rarely drink,  however I was on it during holidays a couple years ago and toasted the celebration with a half glass of champagne. 3 hours later I was burning up & felt like my chest was abt to explode.  1hour after that the vomiting began. I puked my guts up for 15 hours,  had to go to ER for dehydration and was miserable for another day.  I WOULD NOT RECOMMEND ALCOHOL,  EVEN IN TINY AMOUNTS WHILE ON THIS DRUG. IT'LL RUIN YOUR NEXT DAY OR TWO."