Premature ejaculation is the most prevalent male sexual dysfunction.
It is defined in The Merck Manual, a highly regarded reference guide for physicians, as the constant failure to maintain intromission of sufficient duration to satisfy a responsive partner. It is also defined as ejaculation occurring before the individual wishes. Ejaculation is usually preceded by orgasm or climax. Ejaculatory control is an acquired behavior that is minimal in adolescence and increases with experience. According to Merck, normal biologic response is to ejaculate within two minutes of vaginal penetration.