I think this antibiotic causes some people to lose their sense of smell. I was prescribed 500mg/day for 11 days; when I realized that some people were claiming they had lost their sense of taste from it and when I realized this seemed to be an inordinately high dosage, I quit taking it. I realize it could have been something else, but I will not trust a physician so far ever again. Should have known better after other experiences with them.