Clarithromycin is a macrolide antibiotic used to treat pharyngitis, tonsillitis, acute maxillary sinusitis, acute bacterial exacerbation of chronic bronchitis, pneumonia (especially atypical pneumonias associated with Chlamydia pneumoniae or TWAR), skin and skin structure infections. In addition, it is sometimes used to treat Legionellosis, Helicobacter pylori, and lyme disease. Clarithromycin is available under several brand names, for example Crixan, Clarac, Biaxin, Klaricid, Klabax, Klacid, Claripen, Clarem, Claridar, Fromilid, Clacid, Clacee, Vikrol, Infex and Clariwin.