A controlled trial of the use of erythromycin for men with asthenospermia.

A double-blind crossover controlled trial of Erythromycin was conducted in 78 men with asthenospermia (mean pretreatment sperm concentration greater than or equal to 20 X 10(6)/ml and motility less than 60%). Sperm motility increased above the pretreatment mean after the first one month course of treatment for both Erythromycin (7.9 +/- 2.6% P less than 0.01; mean +/- SEM) and the placebo group (7.5 +/- 2.2% P less than 0.01) and also after the second one month course of treatment, given one month after the first, for both Erythromycin (11.8 +/- 2.7% P less than 0.001) and placebo (11.4 +/- 2.8% P less than 0.001). There was no significant difference between the changes in sperm motility with Erythromycin and placebo. Twelve pregnancies occurred during the four month trial time--eight with Erythromycin and four with placebo (chi 2 = 2.51 P = NS). It is concluded that in infertile men, sperm motility tends to increase spontaneously with time. Erythromycin treatment has no significant effect on semen quality and a larger trial will be required to determine if Erythromycin increases fertility.