Usnea is a variety of fruticose lichen that appears to be a webbed mass hanging from the bark and limbs of coniferous and deciduous trees across most of North America, Asia, and Europe. It is also called old man’s beard because of its unkempt appearance. It typically has two filaments: an inner one that is white or yellow in color and an outer one that is green or gray in color. This lichen has been used for thousands of years as a therapeutic medicine for a wide range of medical conditions and for a few personal products.
One of the unusual qualities of usnea is its ability to keep growing when it is broken away from its source. For example, it can be removed from its point of origin on a tree and draped over a wire fence and continue to grow. Part of the reason it can accomplish such a feat is because it can absorb minerals from the air. The downfall to such a unique quality is that it is extremely sensitive to pollutants in the air; if it absorbs too many pollutants, it can die. In fact, although it can be found across the globe, those areas with higher levels of air pollution have minimal or no usnea.
Usnic acid is one of the byproducts from usnea. It works within the lichen to prevent it from becoming overexposed to sunlight and by creating a bitter taste which protects it from hungry predators. It is often extracted for medical and personal uses, as well. For example, it is commonly found in deodorant and soap because it has anti-bacterial qualities. It is also used to make a fermented corn-based drink in Mexico.
Usnea and usnic acid have been used for centuries to treat a variety of illnesses. For example, individuals who suffer from upper respiratory and lung infections take usnea longissima, while those with skin infections and skin ulcers apply it in liquid form to the wound. In addition, the tincture is used to treat tuberculosis for those following traditional Chinese medical guidelines. Human papillomavirus has been also treated with limited effectiveness using usnea and usnic acid.
There are some side effects to using usnea, especially as a weight loss aid. It was combined with other chemicals, and consequently, caused liver failure and heart attacks in some individuals – many of those supplements have been taken off of the market. Since usnea is traditionally used as a topical ointment or only taken orally for a short period of time, there are few problems; however, if it was taken regularly, liver failure, rashes, and severe reaction to some prescription drugs may occur. It is best consult a doctor before consuming usnea or usnic acid orally until more is known about the side effects and how it reacts with certain drugs.