Sulindac is a non-steroidal anti-inflammatory drug of the arylalkanoic acid class that is marketed in the U.S. by Merck as Clinoril. Like other NSAIDs, it is useful in the treatment of acute or chronic inflammatory conditions. Sulindac is a prodrug, derived from sulfinylindene that is converted in the body to an active NSAID. More specifically, the agent is converted by liver enzymes to a sulfide which is excreted in the bile and then reabsorbed from the intestine. This is thought to help maintain constant blood levels with reduced gastrointestinal side effects. Some studies have shown sulindac to be relatively less irritating to the stomach than other NSAID's except for drugs of the COX-2 inhibitor class . The exact mechanism of its NSAID properties is unknown, but it is thought to act on enzymes COX-1 and COX-2, inhibiting prostaglandin synthesis.

Its usual dosage is 150-200 milligrams twice per day, with food. It should not be used by persons with major allergic reactions (urticaria or anaphylaxis) to aspirin or other NSAIDs, and should be used with caution by persons having pre-existing peptic ulcer disease. Sulindac is much more likely than other NSAIDs to cause damage to the liver or pancreas.

Sulindac seems to have a property, independent of COX-inhibition, in reducing the growth of polyps and precancerous lesions in the colon, especially in association with familial adenomatous polyposis.

Sulindac is an effective tocolytic and may be used in the treatment of preterm labour. According to the Cautions distributed with this prescription drug from Walgreens, this medicine has been shown to cause harm to the human fetus.

In common with other NSAIDs, sulindac is currently being investigated for its role in the treatment of Alzheimer's disease.

Since it was found, that the sulfoxide functional group can be reduced by methionine sulfoxide reductase A (MsrA), a possible anti-oxidative capability is being discussed.