A new review (metastudy) has just been published on the effects of various drugs on sexual performance. They found that most drugs, both stimulants and depressants, decrease sexual performance with the following caveats:
Cocaine facilitates erections in ratsCaffeine makes both male and female rats hornyA little bit of booze removes inhibitory tendenciesToo much booze disrupts sexual performance but this wears off over timePfaus claims that '[o]nly animal model studies can provide direct cause and effect data and physiological information' for sexual behavior. Alarm bells should be ringing, only animal studies provide causal relationships of drugs on sexual behavior? Really? Not to sound like a speciesist but we can only say that rat studies can inform our understanding of human sexual behavior. Humans are far more complex neurologically and although cocaine may increase erections in rats it doesn't necessarily mean the same will happen in humans.
Studying animals it is the only logical starting point for studying this sort of behavior but we must be weary when extrapolating the results to humans.
http://www.sciencedaily.com/releases/2010/07/100706103604.htm