Cannabis sativa (a.k.a. pot or hashish, among others) has been in use by physicians, healers and makers of love potions for at least 3000 years, and perhaps more than 5000. It has been credited with arousing abilities by cultures in Africa, Asia and Europe, and made its way into literature that includes 1001 Arabian Nights. The Greeks wrote a fair bit on the subject, and the net was that enough helps libido and too much inhibits it, much like alcohol. The continuing faith in its ability to incite lust was actually a significant factor in its illegalization in the United States, as “reefer madness” was said to contribute to a host of illicit sexual behaviors.
The main active ingredient in marijuana is tetrahydrocannabinol (THC). The chemicals unique to cannabis are called as a whole cannabinoids. While the charges of reefer madness are laughable (I won’t go into their details now), several of the properties of the plant are beneficial to the amorous: relaxation, euphoria, and heightened sensory perception. It also creates an altered perception of time in the user, which one view suggests may give the impression of endless lovemaking, giving pot its aphrodisiac reputation.
I’m not sure I’d call it an aphrodisiac exactly, but it can smooth the road if you’re already a ways down it.