Tolmetin (/ˈtɒlmətɪn/) is a nonsteroidal anti-inflammatory drug (NSAID) of the heterocyclic acetic acid derivative class.

Tolmetin is applicable in the treatment of rheumatoid arthritis,[2][3] osteoarthrosis,[4][5] pain,[6] and ankylosing spondylitis.

[7] Although the mechanism of action of tolmetin is unknown, research involving humans and animals has shown that tolmetin does not achieve anti-inflammatory response by stimulation of the adrenal or pituitary gland, but it has shown tolmetin restrains prostaglandin synthetase in vitro and reduces plasma levels of prostaglandin E, possibly causing the anti-inflammatory response.

When tested in rats, tolmetin prevented experimentally stimulated polyarthritis and reduced inflammation.

In October 2020, the U.S. Food and Drug Administration (FDA) required the drug label to be updated for all nonsteroidal anti-inflammatory medications to describe the risk of kidney problems in unborn babies that result from low amniotic fluid.