Clarithromycin

Clarithromycin, antibiotic drug used to treat respiratory tract and skin infections such as pneumonia, tonsillitis (swollen and inflamed tonsils), and bronchitis. The drug works by interfering with the formation of proteins in the invading bacteria, thereby preventing their growth and multiplication.

Available by prescription only, tablets are taken orally, usually in 250- to 500-mg doses every 12 hours. They may be taken with or without food. Effectiveness in controlling infection is usually apparent after 4 to 6 days, although the complete, prescribed treatment (usually 7 to 14 days) should be taken even if symptoms have subsided to prevent a recurring infection.

Patients with kidney disease or a sensitivity to erythromycin or similar antibiotics should avoid this drug or use it with caution. Clarithromycin has not been proven safe for children under the age of 12 or for pregnant women. Breast-feeding mothers should be aware that the drug may appear in breast milk.

The drug’s side effects are usually minimal, but may include nausea, indigestion, diarrhea, headache, or an altered sense of taste. Severe diarrhea, sometimes caused by the drug’s effect on the intestine, requires immediate medical attention.

Clarithromycin may interact adversely with blood-thinning drugs such as warfarin, as well as with the drugs carbamazepine, theophylline, astemizole, digoxin, and phenytoin.