Clarithromycin, sold under the brand name Biaxin, is an antibiotic used to treat various bacterial infections.This includes strep throat, pneumonia, skin infections, H. pylori infection, and Lyme disease, among others. Clarithromycin can be taken by mouth as a pill or liquid.

Common side effects include nausea, vomiting, headaches, and diarrhea. Severe allergic reactions are rare. Liver problems have been reported. It may cause harm if taken during pregnancy. It is in the macrolide class and works by decreasing protein production of some bacteria.