According to a study, 5 alpha reductase inhibitors found in such drugs interfere with the effect of certain male hormones (androgens) on the prostate.

Researchers led by Abdulmaged M. Traish of Boston University School of Medicine examined data reported from available literature concerning the side effects of the 5 alpha reductase inhibitors, finasteride and dutasteride.

Prolonged adverse side effects on sexual function, depression and diminished libido were reported by a subset of men, The Journal of Sexual Medicine reports.

Drug-related reduction in libido occurred in 4.2 percent and 1.8 percent of patients in the dutasteride and placebo groups respectively.

Reduced ejaculation and semen volume were also reported. In some patients, these drugs were associated with depression, according to a Boston University statement.

"For these reasons, patients and doctors are urged to discuss these issues openly and candidly and assess the risk benefit ratio prior to commencing therapy with 5 a-reductase inhibitors," Traish noted.