Biaxin is an antibiotic related to Erythromycin. There are basically two types--plain Biaxin and Biaxin XL. Biaxin XL has fewer side effects than the original formulation, and both have fewer side effects than erythromycin. The drug rep recommended drinking some orange juice to help with any metallic taste in the mouth. I've taken the medications (both formulations) and the orange juice helps; so does careful brushing and flossing of the teeth, to be honest about it. The diarrhea can be helped in some instances by taking it with a small amount of food, although GI problems are less common. If you were concerned about something else in particular, please PM me, I might be able to answer your concern. (I am a family physician).