The willow is a family of plants encompassing trees and shrubs native to North America, Asia and Europe. The bark of these plants has long been regarded for its medicinal properties when ground into powder and consumed in an herbal infusion. Though it's postulated that willow bark had been in use by Chinese cultures prior, the first treatise on willow bark was written by Hippocrates in roughly 400 BC.
Inflammation and Pain
The active ingredient in willow tree bark is a chemical called salicin. When consumed, the body metabolizes it into a chemical called salicylic acid. Aspirin, a synthetic version chemically known as acetylsalicylic acid, has the same properties but can irritate the stomach lining. In any case, salicylic acid acts on prostaglandin. Prostaglandin is an enzyme created by most cells of the body. Its role is to hypersensitize pain receptors and cause an influx of blood around the sight of an injury. Likewise, prostaglandin congregates in joints in people who suffer from bursitis, tendinitis and arthritis. Salicylic acid binds with prostaglandin and prevents it from creating inflammation and pain.
Willow tree bark, when ground and applied to the skin, can cure many skin conditions. This is because salicylic acid works as a keratolytic, a chemical that causes the outer layer of the skin to loosen and shed. It also softens the keratin, an important component of the skin. As a result, willow tree bark can be used to cure acne, corns, minor warts, calluses and psoriasis.
When someone is cut, the blood clots when platelets rush to the site of the cut and absorb moisture until the blood becomes dry. Salicylic acid, when introduced to the bloodstream, has the mild effect of killing platelets by slightly altering blood acidity. This means that salicylic acid is a blood thinner, one habitually used as a preventative in people who are at risk for blood clots and heart attack. Conversely, overdose of salicylic acid can cause symptoms congruent with hemophilia, a condition where the blood fails to clot entirely and a person can bleed to death. It also increases the risk of ischemic stroke, wherein blood leaks into the brain.