Sulfamethoxazole / trimethoprim
"For someone who has always suffered from medical issues (Crohns Disease, eczema, heart murmur) I'm no stranger to medications.  I have a simple bacterial infection in my belly button and my doctor put me on this drug (2x daily for 7 days).  After 24 hours I was nauseous constantly and spent my time in bed or the bathroom.  After pill five I am completely incapacitated.  After reading these comments and seeing how many other people share my troubles, I will be stopping if my own accord and never taking this again.  Especially not for a simple bacterial infection that has never caused me any problems in the first place.  I now know learned I will always research a drug before taking it."