cox-2 inhibitors are a special type of analgesic. cyclooxygenase (commonly abbreviated as cox) is an enzyme that has an important role in starting an inflammation and pain. there are many different types of cox; the most common are known as cox-1 and cox-2. nsaids work by blocking cox. the problem with blocking all cox is that cox-1 is also used to regulate kidney function. blocking cox-1 runs the risk of bleeding of the stomach, and reduction of the kidney function. cox-2 inhibitors only block cox-2, and do not have an effect on cox-1.. clinical studies have shown that they increase the risk of a heart attack, and of a stroke. several cox-2 inhibitors have been taken off the market, because of these side-effects.