Naproxen is a member of the arylacetic acid group of nonsteroidal anti-inflammatory drugs (NSAIDs). Naproxen has analgesic and antipyretic properties. Like most NSAIDs, naproxen is a non-selective prostaglandin G/H synthase (a.k.a. cyclooxygenase or COX) inhibitor that acts on both prostaglandin G/H synthase 1 and 2 (i.e. COX-1 and -2). COX catalyzes the conversion of arachidonic acid to a number of prostaglandins involved in fever, pain, swelling and inflammation. Naproxen antagonizes COX by binding to the upper portion of the active site, preventing its substrate, arachidonic acid, from entering the active site. The analgesic, antipyretic and anti-inflammatory effects of naproxen occur as a result of decreased prostaglandin synthesis.