Users may exhibit sexually compulsive behavior while under the influence. This disregard for the potential dangers of unprotected sex or other reckless sexual behavior may contribute to the spread of sexually transmitted diseases (STD's). Concern over the use of methamphetamine resulting in risky sexual practices has been especially visible in the gay community (however the dangers posed to heterosexual couples is no less).

Among the effects reported by methamphetamine users is an increase in the need and urgency for sex, the ability to have sex for extended periods of time, and an inability to ejaculate or reach orgasm or physical release.

In addition to increasing the need for sex and enabling the user to engage in marathon sex sessions, methamphetamine lowers inhibitions and may cause users to behave recklessly or to become forgetful. According to a recent San Diego study, methamphetamine users often engage in unsafe sexual activities, and forget or choose not to use condoms. The study found that methamphetamine users were a sixth as likely to use condoms.

The urgency for sex combined with the inability to achieve release (ejaculation) can result in tearing, chafing, and trauma (such as rawness and friction sores) to the sex organs, the rectum, and mouth dramatically increasing the risk of transmission of HIV and other sexually transmitted diseases. Methamphetamine also causes erectile dysfunction (though the term has more rarely been used to describe the extreme urge for sex experienced by many methamphetamine users), which often leads people to decide to engage in receptive anal sex or fisting.