There exists in medical practice at the close of the 20th century two basic categories of anti-inflammatory drugs: steroidal (from steroid compounds) and non-steroidal.Steroids are given their own section in this volume. They are potent inhibitors of inflammation and the immune system, but also have a host of serious, even deadly, side-effects. The non-steroidal agents are in general less potent but also have fewer side-effects and will be the subject of this section.

In the mid 1700s, Reverend Edmund Stone wrote a letter to the English Royal Society noting the ability of the bark of the willow tree to cure fever. He was reiterating an observation known for ceturies by many cultures, but the actual ingredient remained unknown until 1829 when Leroux isolated salicin. Salicin indeed proved to decrease fever. Chemically salicin can be converted to salicilic acid, a very successful treatment of fever and gout...