Some drugs, such as cocaine and MDMA, increase sensual and erotic sensations, though both may inhibit sexual intercourse itself by causing temporary erectile dysfunctions.
Date rape drugs, such as rohypnol, are notorious for being used to render victims unconscious, dissociated, or severely sedated and thus easy targets for sexual assault.
Perhaps the most common drug used is alcohol. At low concentrations of blood alcohol, social inhibitions are reduced, though in higher concentrations it can also inhibit performance. Many other drugs also inhibit sexual performance.
Because drug and alcohol use is commonly presented as an excuse for unacceptable behaviour, it is necessary to treat the idea of a direct causal relation between drug use and unsafe sex with caution. Drugs may provide a socially acceptable excuse for engaging in sexual behaviours in which people may want to engage but perhaps know that they should not.
Tobacco use (e.g., cigarette smoking), also reduces sexual function, with the incidence of impotence being approximately eighty-five percent higher in male smokers compared to non-smokers.