NSAIDs increase the risk of potentially fatal, stomach and intestinal adverse reactions (for example, bleeding, ulcers, and perforation of the stomach or intestines ). These events can occur at any time during treatment and without warning symptoms. Elderly patients are at greater risk for these adverse events. NSAIDs (except low dose aspirin) may increase the risk of potentially fatal heart attacks , stroke , and related conditions. This risk may increase with duration of use and in patients who have underlying risk factors for heart and blood vessel disease. Therefore, NSAIDs should not be used for the treatment of pain resulting from coronary artery bypass graft ( CABG ) surgery.
NSAIDS have antipyretic activity and can be used to treat fever.   Fever is caused by elevated levels of prostaglandin E2 , which alters the firing rate of neurons within the hypothalamus that control thermoregulation.   Antipyretics work by inhibiting the enzyme COX, which causes the general inhibition of prostanoid biosynthesis ( PGE2 ) within the hypothalamus .   PGE2 signals to the hypothalamus to increase the body's thermal set point.   Ibuprofen has been shown more effective as an antipyretic than paracetamol (acetaminophen).   Arachidonic acid is the precursor substrate for cyclooxygenase leading to the production of prostaglandins F, D & E.