In a study of HIV infected men who have sex with men, it was found that methamphetamine use was associated with high rates of anal sex, low rates of condom use, multiple sex partners, and anonymous sex.

Users reported using the drug to promote sexual pleasure and to reduce negative feelings associated with being HIV infected. This was also demonstrated in a study of male homosexual and heterosexual non-injecting amphetamine users attending HIV clinics in California. In contrast, being HIV infected has been shown to be associated with condom use among amphetamine injectors in Sweden.

There is evidence of a link between amphetamine use and risky sexual behaviour in east and south-east Asia, and thus the recent increase in the availability of drugs in the region has implications for HIV control. In an HIV vaccine trial among injecting drug users in Bangkok, amphetamines use was associated with vaginal intercourse.

Ecstasy use has mainly been studied in industrialized countries. Compared to those who use amphetamines but not ecstasy, ecstasy users tend to be of a higher socio-economic status and have more same sex partners. There is evidence that ecstasy use is associated with unsafe sexual activity....In a study of young homosexual and bisexual men in New York City, ecstasy use was associated with having more male partners... and greater likelihood of having unprotected anal sex.

Opioid use and sexual HIV transmission: heroin is believed to reduce sexual activity and impair sexual arousal. However, there is significant evidence that heroin dependent individuals engage in sexual activity. In a study of predominantly heroin injecting drug users in London, 80 per cent had been sexually active within the preceding six months, with an average of 2.1 non-commercial opposite sex partners.

?Across most studies, there is a clear link between the regularity of sexual intercourse with the primary sexual partner and the frequency of condom use. Condom use is low with regular partners of heroin users, especially within marriage, and higher with casual partners.

The severity of opioid dependence usually increases the likelihood of risky sexual behaviour. Severe dependence can also lead to an increase in commercial sex work, and, consequently, reduced use of condoms. Evidence suggests that sex workers who inject drugs face increased risk of sexual HIV transmission because they often have a higher number of clients... and have sexual partners who also inject drugs. Sex workers who inject are also more likely to pass on HIV if infected. Lower levels of condom use have been shown among those injecting drugs and selling or buying sex.... Among injecting drug users in Vancouver, Canada, and in several cities of the United States, condom use with all types of sexual partners (paying, casual, and primary partners) is rare or low among those exchanging sex for drugs or money.

Female drug users are more likely than male drug users to trade sex for drugs. In an analysis of 1,055 drug users in the US, female users were more than three times more likely to engage in trading sex for drugs than male users.... Homelessness, unemployment and the use of crack (in order of decreasing correlation) were all associated with trading sex for drugs.