Indometacin, also known as indomethacin, is a nonsteroidal anti-inflammatory drug (NSAID) commonly used as a prescription medication to reduce fever, pain, stiffness, and swelling from inflammation. It works by inhibiting the production of prostaglandins, endogenous signaling molecules known to cause these symptoms. It does this by inhibiting cyclooxygenase, an enzyme that catalyzes the production of prostaglandins. It was patented in 1961 and approved for medical use in 1963. It is on the World Health Organization's List of Essential Medicines. In 2020, it was the 320th most commonly prescribed medication in the United States, with more than 800thousand prescriptions. Medical uses As an NSAID, indometacin is an analgesic, anti-inflammatory, and antipyretic. Clinical indications for indometacin include: Joint diseases rheumatoid arthritis ankylosing spondylitis osteoarthritis gouty arthritis acute painful shoulder bursitis or tendinitis Headaches Trigeminal autonomic cephalgias Paroxysmal hemicranias Chronic paroxysmal hemicrania Episodic paroxysmal hemicrania Hemicrania continua Valsalva-induced headaches Primary cough headache Primary exertional headache Primary headache associated with sexual activity (preorgasmic and orgasmic) Primary stabbing headache (jabs and jolts syndrome) Hypnic headache Others Patent ductus arteriosus Contraindications Concurrent peptic ulcer, or history of ulcer disease Allergy to indometacin, aspirin, or other NSAIDs Roux-en-Y gastric bypass and gastric sleeve patients Patients with nasal polyps reacting with an angioedema to other NSAIDs Children under 2 years of age (with the exception of neonates with patent ductus arteriosus) Severe pre-existing renal and liver damage Caution: pre-existing bone marrow damage (frequent blood cell counts are indicated) Caution: bleeding tendencies of unknown origin (indometacin inhibits platelet aggregation) Caution: Parkinson's disease, epilepsy, psychotic disorders (indometacin may worsen these conditions) Concurrent with potassium sparing diuretics Patients who have a patent ductus arteriosus dependent heart defect (such as transposition of the great vessels) Significant hypertension (high blood pressure) Concomitant administration of lithium salts (such as lithium carbonate) Adverse effects In general, the adverse effects of indometacin are similar to those of all other NSAIDs. For instance, indometacin inhibits both cyclooxygenase-1 and cyclooxygenase-2, which then inhibits the production of prostaglandins in the stomach and intestines responsible for maintaining the mucous lining of the gastrointestinal tract. Indometacin, therefore, like other non-selective COX inhibitors, can cause peptic ulcers. These ulcers can result in serious bleeding or perforation, requiring hospitalization of the patient. To reduce the possibility of peptic ulcers, indometacin should be prescribed at the lowest dosage needed to achieve a therapeutic effect, usually between 50 and 200 mg/day. It should always be