Damiana leaves are harvested from the plant Turnera diffusa, a small shrub native to Mexico. Besides being used in the production of a popular Mexican liqueur called Damiana, this herb has enjoyed a long and unwarranted history of use as an aphrodisiac, supposedly able to stimulate the libido of men and women alike.
It is also regarded as an important folk medicine in Mexico, often used to treat sterility, impotence, diabetes, bladder infection and asthma. Damiana is also said to possess mild sedative qualities, able to induce a state of relaxation and to aid in falling asleep.
Modern studies of the chemical composition of damiana list tannin, resin, and volatile oils, which, while considered relatively safe for consumption, offer no evidence to support the host of claims for this plant. Indeed, the data suggests that it is the high alcohol content of damiana liquor and its tinctures that is the responsible agent for most if not all of its perceived effects.