Why do nonsteroidal anti-inflammatory drugs (NSAIDs) cause side effects?

Leopold D. Galland, MD
Internal Medicine
NSAIDs (nonsteroidal anti-inflammatory drugs) include common over-the-counter drugs such as aspirin (Bayer, Bufferin and Excedrin), ibuprofen (Advil, Motrin and Nuprin), and naproxen (Aleve). They relieve pain and inflammation by blocking an enzyme called cyclo-oxygenase (COX).

Although COX activity contributes to pain and inflammation, this enzyme also performs important functions such as:
  • Protecting the stomach from the corrosive effects of its own acid
  • Regulating circulation of blood to the kidneys
  • Modulating the activity of the immune system
NSAID use can have severe side effects, which are a direct result of COX inhibition. The documented side effects of chronic NSAID use include:
  • Stomach ulcers
  • Intestinal bleeding
  • Kidney failure
  • High blood pressure
  • Aggravation of immune system disorders like asthma, psoriasis and colitis

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