Postgonococcal urethritis: a double-blind study of doxycycline vs placebo.

The occurrence of postgonococcal urethritis (PGU) was studied in heterosexual men who were randomly assigned to receive either oral doxycycline 100 mg or a placebo capsule twice daily for seven days in addition to routine single dose treatment of urethral gonorrhoea. Of 216 patients suitable for assessment, PGU was diagnosed in 54/104 (51.9%) in the placebo group and 30/112 (26.8%) in the doxycycline group. Symptomatic PGU was uncommon (6.7% in the placebo group, 2.7% in the doxycycline group). Persistence of chlamydial infection at first follow-up was associated with the development of PGU in the placebo group (p less than 0.05). Although PGU developed in 10/12 (83%) patients in whom Mycoplasma hominis was isolated on entry to the study, the association was not statistically significant. The development of PGU was not associated with the isolation of Ureaplasma urealyticum. A significant reduction in the incidence of PGU was achieved by the addition of a course of doxycycline (p less than 0.001), but there remained a considerable proportion of patients in whom the aetiology of PGU was unknown.