These drugs are chemically related and have similar uses, but because they are distributed differently in the body, they may be used for different purposes. There are other, older drugs in this group, but they are no longer in general use.
Erythromycin is similar in use to penicillin and is widely used for patients who are allergic to penicillin. Penicillin has advantages over erythromycin in that it kills bacteria, while erythromycin only stops bacterial growth and relies on the body's immune system to kill bacteria. Also, erythromycin is more likely to cause stomach upset than is penicillin. Sometimes erythromycin may be used to treat a microorganism that is resistant to penicillin.
Azithromycin and clarithromycin both reach the lungs and respiratory tract better than does erythromycin. These two drugs may be preferred for respiratory tract infections.
Clindamycin and lincomycin are similar to each other and are more effective than erythromycin for treatment of infections caused by anaerobic bacteria. Anaerobic bacteria can grow in the absence of oxygen.
Symptoms should begin to improve within a few days of beginning to take this medicine. If they do not, or if they get worse, parents should check with the physician who prescribed the medicine.
Erythromycins may cause mild diarrhea that usually goes away during treatment. However, severe diarrhea could be a sign of a very serious side effect. Anyone who develops severe diarrhea while taking erythromycin or related drugs should stop taking the medicine and call a physician immediately.
Nancy Ross-Flanigan, Samuel Uretsky PharmD, Thomson Gale, Gale, Detroit,