Single-dose Tamsulosin Induces Reversible Azoospermia and Ejaculatory Dysfunction Suggesting Potential for on-demand Male Contraception

PURPOSE: Ejaculatory alterations are among the most frequent sexual side effects of α₁-adrenergic antagonists. Although often attributed to retrograde ejaculation, recent evidence indicates that tamsulosin primarily disrupts seminal emission, occasionally leading to transient azoospermia. This study evaluated the frequency, timing, and reversibility of ejaculatory and seminal changes following a single oral dose of 0.8 mg tamsulosin in healthy men. MATERIALS AND METHODS: Thirty-one healthy male volunteers (aged 18-45 years) underwent a baseline semen analysis, followed by six additional collections at 1-3 week intervals. Each collection was performed at a different post-dose time point, spaced every 4 hours, to construct a 24-hour post-administration profile. Semen parameters were assessed according to WHO criteria, and post-ejaculatory urine was examined to detect retrograde ejaculation. Temporal variations were analyzed using repeated-measures ANOVA, with effect sizes estimated by Cohen's d. RESULTS: Seminal volume decreased significantly in 93.6% of participants, with aspermia in 80.7%, peaking 12 h after ingestion (p