Clarithromycin is a semi-synthetic macrolide antibiotic. Chemically, it is 6-0-methylerythromycin. The molecular formula is C38H69NO13, and the molecular weight is 747.96.

Clarithromycin is a white to off-white crystalline powder. It is soluble in acetone, slightly soluble in methanol, ethanol, and acetonitrile, and practically insoluble in water.

Clarithromycin is an antibiotic approved for treatment of common bacterial infections in non-immunocompromised individuals. Clarithromycin is used orally for the treatment of upper and lower respiratory tract and skin and skin structure infections. Clarithromycin is approved for the treatment of MAC. It may also be useful alone, or in combination with azithromycin, for the treatment of toxoplasmosis. Clarithromycin may be an effective prophylaxis treatment for toxoplasmosis and MAC. Recent Public Health Service recommendations suggest either clarithromycin or azithromycin as the first line treatment for MAC, along with at least one other drug, usually ethambutol and one of the following: ciprofloxacin or rifabutin.

Clarithromycin is an antibiotic used to treat certain infections caused by bacteria, such as pneumonia; bronchitis; and ear, lung, sinus, stomach, skin, and throat infections. It also is used to prevent disseminated Mycobacterium avium complex (MAC) infection. Antibiotics will not work for colds, flu, or other viral infections.

For pharyngitis/tonsillitis due to Streptococcus pyogenes, acute maxillary sinusitis due to Haemophilus influenzae, Moraxella catarrhalis or Streptococcus pneumoniae, acute bacterial exacerbation of chronic bronchitis due to Haemophilus influenzae, Haemophilus parainfluenzae Moraxella catarrhalis or Streptococcus pneumoniae, community-acquired pneumonia due to Haemophilus influenzae, Mycoplasma pneumoniae, Streptococcus pneumoniae or Chlamydia pneumoniae, Uncomplicated skin and skin structure infection due to Staphylococcus aureus, Streptococcus pyogenes, Disseminated mycobacterial infection due to Mycobaterium avium or Mycobacterium intracellulare.