urinary tract infection
"After having severe headache and vomiting with a sulfa drug, I was put on Macrobid for my UTI.  I got a little headache after second dose, but popped a Tylenol.  Also, made sure I took my pills with food. I was able to finish the full regimen and although the UTI took a bit longer to get kicked out, the Macrobid worked.  It really wasn't bad at all to take.  I have many food allergies, too, and was able to tolerate Macrobid pretty well."