Indomethacin is a nonsteroidal anti-inflammatory drug (NSAID), prescribed primarily for its anti-inflammatory, analgesic, and fever-reducing properties. Like many medications in this class, Indomethacin is associated with potential side effects, particularly those affecting the digestive system. A common concern involves changes in bowel function, including the potential for diarrhea.
What Indomethacin Treats
Indomethacin manages the symptoms of various inflammatory conditions. It is frequently prescribed for moderate to severe rheumatoid arthritis, ankylosing spondylitis, and osteoarthritis, helping reduce swelling, stiffness, and joint pain. The drug is also effective for the short-term treatment of acute painful shoulder, often caused by bursitis or tendinitis. Indomethacin is a standard treatment for acute gouty arthritis, rapidly alleviating the intense pain and inflammation characteristic of gout flares.
Diarrhea and Other Gastrointestinal Effects
Diarrhea is a common gastrointestinal (GI) side effect of Indomethacin, occurring in 1% to 10% of users taking the oral capsule. This symptom often appears alongside other digestive complaints, which are more frequently reported. Nausea is a very common side effect, sometimes affecting up to 34% of people. Other related issues include vomiting, dyspepsia, and general abdominal discomfort. While diarrhea is usually mild and temporary, its occurrence confirms the drug’s significant interaction with the digestive system.
The Drug’s Impact on Gut Function
Indomethacin exerts its therapeutic effects by inhibiting cyclooxygenase (COX) enzymes, specifically both COX-1 and COX-2 isoforms, which are responsible for producing prostaglandins. Prostaglandins are lipid compounds that play a major role in mediating inflammation.
Upper GI Effects
The inhibition of the COX-1 enzyme leads to adverse GI effects because this isoform produces prostaglandins that maintain the protective mucous barrier of the stomach lining. When this protective layer is diminished, the stomach and upper intestine become vulnerable to irritation from stomach acid, which can lead to inflammation and ulcer formation.
Lower GI Effects and Diarrhea
Beyond upper GI irritation, the drug also affects the lower digestive tract, which contributes directly to diarrhea. Prostaglandins are involved in regulating the balance of fluid and electrolytes in the gut. By disrupting this prostaglandin-mediated balance, Indomethacin can alter intestinal permeability and lead to increased water secretion into the bowel. This influx of fluid results in the watery stools characteristic of drug-induced diarrhea.
Monitoring and Seeking Medical Guidance
Patients taking Indomethacin should be vigilant for any persistent or severe changes in their digestive health. While mild diarrhea can often be managed by staying well-hydrated, more serious symptoms require immediate medical attention.
Signs of a serious gastrointestinal complication include bloody or black, tar-like stools, which indicate bleeding in the digestive tract. Persistent vomiting, especially if the vomit looks like coffee grounds, also warrants prompt medical evaluation. Contact a healthcare provider immediately if diarrhea lasts longer than 48 hours or is accompanied by signs of dehydration, such as severe dizziness, dry mouth, or reduced urination. Taking Indomethacin with food or milk, as directed by a physician, can help minimize the risk of stomach irritation.