Clinical history:

After an unprotected sexual exposure, a 44-year old man came to us with symptoms of anterior dysuria and scanty mucoid urethral discharge. Diagnosed non-gonococcal urethritis with pus cells found on urethral smear and with a negative history of drug allergy we prescribed a course of tetracycline 500mg QID for seven days. On the third day after prescription, he came back with a swollen plaque on his right forearm. On more careful questioning he admitted a history of skin eruption on the same site twenty years before following taking an unknown drug for a similar problem. That rash subsided in two weeks with a residual grayish patch which took 5 years to fade.

Physical examination showed an oedematous erythematous patch on the right forearm with intense itchiness. Tetracycline was stopped and the lesion was treated with KMnO4 compresses and anti-histamine. It subsided in 10 days with grayish pigmentation. We completed the treatment of non-gonococcal urethritis with a single dose of azithromycin 1gm without any side effects.