OH GOD, i took biaxin for this horrible tonsil infection i had about a year ago, and it made my stomach constantly sick and gave me that awful, bitter taste in my mouth all the time i was taking it. it did not go away until all the medicine was out of my system, to tell you the absolute truth. i will never ever ever ever everrrrrr take it again. it's just that i'm allergic to pretty much everything else, so that's where my problem comes in.