Aspirin, or acetylsalicylic acid (ASA) (IPAEng: əˌsɛtɨlsælɨˌsɪlɨk ˈæsɨd), is a salicylate drug, often used as an analgesic to relieve minor aches and pains, as an antipyretic to reduce fever, and as an anti-inflammatory medication.

In countries where Aspirin is a registered trademark owned by Bayer, the generic term is "ASA."

Aspirin also has an antiplatelet or "anti-clotting" effect and is used in long-term, low doses to prevent heart attacks, strokes and blood clot formation in people at high risk for developing blood clots. It has also been established that low doses of aspirin may be given immediately after a heart attack to reduce the risk of another heart attack or of the death of cardiac tissue.

The main undesirable side effects of aspirin are gastrointestinal—ulcers and stomach bleeding—and tinnitus, especially in higher doses. In children under 19 years of age, aspirin is no longer used to control flu-like symptoms or the symptoms of chickenpox, due to the risk of Reye's syndrome.

Aspirin was the first-discovered member of the class of drugs known as non-steroidal anti-inflammatory drugs (NSAIDs), not all of which are salicylates, although they all have similar effects and most have some mechanism of action which involves non-selective inhibition of the enzyme cyclooxygenase. Today, aspirin is one of the most widely used medications in the world, with an estimated 40,000 metric tons of it being consumed each year.

History

Main: History of aspirin

Medicines containing derivatives of salicylic acid, structurally similar to aspirin, have been in medical use since ancient times. Salicylate-rich willow bark extract became recognized for its specific effects on fever, pain and inflammation in the mid-eighteenth century. By the nineteenth century pharmacists were experimenting with and prescribing a variety of chemicals related to salicylic acid, the active component of willow extract.

A French chemist, Charles Frederic Gerhardt, was the first to prepare acetylsalicylic acid (named aspirin in 1899) in 1853. In the course of his work on the synthesis and properties of various acid anhydrides, he mixed acetyl chloride with a sodium salt of salicylic acid (sodium salicylate). A vigorous reaction ensued, and the resulting melt soon solidified. Since no structural theory existed at that time, Gerhardt called the compound he obtained "salicylic-acetic anhydride" (wasserfreie Salicylsäure-Essigsäure). This preparation of aspirin ("salicylic-acetic anhydride") was one of the many reactions Gerhardt conducted for his paper on anhydrides, and he did not pursue it further.