Seligiline is an antidepressant originally used to treat Parkinson’s disease. It also appears to boost libido and fend off aging. Experiments with the usual mice and rats resulted in a life span increase of over 30% and copulation like there was no tomorrow.
A dose of 5 milligrams taken twice a week would seem to yield few side effects, and anecdotal evidence suggests definite aphrodisiac results. You’ll need a prescription, though, and its association with illicit drug use, particularly odd Ecstasy mixes, makes going outside the system a rather risky bet.