Usnic acid is extracted from Usnea, Usnea, also known as old man’s beard, is not a plant but a lichen—a symbiotic relationship between an algae and a fungus. The entire lichen is used medicinally. Usnea looks like long, fuzzy strings hanging from trees in the forests In natural remedies, especially in the veterinary medicine, Usnic Acid is used in powders and ointments for the treatment of infections of the skin. Usnic acid as a pure substance has been formulated in creams, toothpaste, mouthwash, deodorants and sunscreen products, in some cases as an active principle, in others as a preservative.