Damiana is a shrub native to Texas, Mexico and Central and South America. Its leaves have been used medicinally for hundreds of years, and it was used as an aphrodisiac by the Mayan people.
Damiana contains 22 flavonoids and a potent mix of phenolics, fatty acids and caffeine. One of its most active ingredients is apigenin, which is known to have anti-anxiety and mild sedative effects. It's probably the apigenin which is behind the use of damiana as a herbal remedy for depression and anxiety.
The use of damiana leaf as an aphrodisiac and sexual potency enhancer is widespread, but there have been no human studies into its effectiveness in this area. Animal studies did show a small effect.
As a herbal remedy, damiana leaf is also thought to be effective against bedwetting, and some people like to use it to relieve tension headaches.
Damiana leaf can be bought dried to use in tea or to smoke, or it can be bought in tablet and capsule form. It can also be extracted into an essential oil; in aromatherapy, damiana is thought to be an all round tonic for the nervous system.