Treatment of Chlamydia trachomatis infections: comparison of 1- and 2-g doses of erythromycin daily for seven days.

Erythromycin is recommended as the alternative to tetracyclines for the treatment of Chlamydia trachomatis infections. However, the usual dose of erythromycin (2 g daily for a week) is frequently associated with gastrointestinal side effects. The goal of this study was to determine whether 1 g of erythromycin daily for a week would be as effective as the 2-g daily dose but without the adverse gastrointestinal effects associated with the larger dose. A total of 114 patients were entered into a randomized double-blind study; 76 patients completed treatment, 13 patients discontinued treatment because of adverse effects, and 25 failed to complete therapy or to return after treatment was initiated. Twelve (27%) of the 45 patients treated with 1 g of erythromycin had cultures positive for C. trachomatis after therapy, as compared with three (10%) of 31 patients treated with a 2-g dose. Only 34% of those treated with 1 g of erythromycin developed adverse gastrointestinal effects, as compared with 71% of those who received 2 g of the drug. Of the 13 patients who discontinued treatment because of side effects, 11 were receiving the 2-g dose. This study indicates that the smaller 1-g dose of erythromycin is inadequate therapy for C. trachomatis infections and that the standard 2-g dose is frequently associated with adverse effects that require discontinuation of therapy.