White willow bark is a tree native to Europe and Asia. The name “white willow” comes from the color of the leaves, which are covered with fine white hairs.
The medicinal use of white willow bark goes incredibly far back. Ancient Egyptians used white willow for inflammation. The Greek physician Hippocrates wrote about white willow’s medicinal uses in 5th century B.C..
In 1829, scientists in Europe identified what was believed to be the active ingredient in white willow bark—a compound called salicin. Public demand grew rapidly.
Extracting salicin from herbs was considered to be expensive and time-consuming, so a synthetic salicylic acid version was developed in Germany in 1852 and quickly became the treatment of choice (salicin is converted in the body to salicylic acid).
The problem was that it was harder on the stomach. At therapeutic doses, people using the synthetic salicylic acid developed stomach ulcers and bleeding.
The German company Bayer eventually created a synthetic, less harsh derivative of salicylic acid, called acetylsalicylic acid (ASA), and mass-produced it under the name aspirin. Despite this, aspirin is still known for irritating the stomach lining.
White willow bark is used for conditions that cause pain, inflammation, or fever, such as:
People take white willow bark instead of aspirin because it does not appear to be as irritating to the stomach lining. It may be because the salicin found naturally in white willow bark is only converted to the acid form after it is absorbed by the stomach.
Researchers have also suggested that white willow bark is more effective than aspirin because of other active compounds that are found in the bark, but not the drug. Animal research at Cairo University compared a willow bark extract to ASA and found that a willow bark extract was as effective as aspirin in reducing inflammation, even though the salicin content was lower than an equivalent dose of ASA.