Salicylic acid is an acid that is nowadays used for external treatment to remove the outer layer of the skin. Therefore, salicylic acid is good for treating acne, psoriasis, calluses, corns, keratosis pilaris and warts. The compound can be obtained from the bark of white willow and the leaves of wintergreen, but, due to its relatively simple structure, is now mainly produced synthetically. It has bacteriostatic, fungicidal and keratolytic effects, and when taken orally, analgesic and antipyretic.
Willow has been used for medicinal purposes for a very long time. There are records of its use as far back as 1500 B.C. Its use for fever and pain can be observed over time and many different cultures. An extract of willow bark, called salicin after the Latin name of the white willow (Salix alba), was isolated and named by the German chemist Johann Andreas Buchner in 1828. The German chemist Hermann Kolbe succeeded in producing the substance fully synthetically for the first time in the 1850s. The bitter taste of the substance and side effects such as stomach complaints, prompted many scientists to search for alternatives. At the turn of the century, the acetylated form, acetylsalicylic acid, was introduced to the market. Due to its significantly improved side effect profile, acetylsalicylic acid largely replaced salicylic acid for the treatment of fever and pain.