Usnea has been used in Chinese medicine for more than three thousand years. Considered a bitter, cool medicine, usnea is antibiotic, antifungal, antispasmodic, antipyretic, and analgesic. Early Chinese herbalists administered usnea orally as an expectorant and topically to treat infections and ulcers. Today, it is used as a tincture or infusion to treat tuberculosis and bronchitis, and applied locally to help heal infected wounds. The German E commission monographs approve usnea for treating inflammations of the mucous membranes in the mouth and larynx, and American herbalists utilize it for the treatment of lung infections, tuberculosis, urinary tract infections, Candida albicans, and strep throat.
Usnic acid is a type of chemical extracted from usnea, a type of lichen also known as old man's beard, because of its resemblance to human facial hair. When extracted from the plant, it is yellow and crystalline in appearance. Mixed with water, however, it loses its yellow tint and appears colorless. Usnic acid is known to exhibit antibacterial properties. In the United States, usnic acid (as a powder or ointment) is used to treat primarily skin infections, and has been shown to be effective in treating tuberculosis bacteria, as well as other pathogenic fungi. Pure usnic acid is also used in many types of creams, toothpastes, deodorants and sunscreens as a protectant and a preservative. Externally, it has been used to treat conditions such as ringworm and athlete's foot. It is used both in humans and
on animals.