COX-2 inhibitors are taken to reduce pain, swelling and inflammation. These drugs operate by stopping the production of the drug cyclooxygenase-2 which is responsible for the production of the hormone prostaglandin. This is the hormone that acts as chemicals messengers for inducing the sensation of pain.

However the intake of this drug can come with a number of side-effects. One of the most common side-effects is insomnia, where the patient suffers from being unable to sleep. This results in the patient displaying daytime drowsiness and exhaustion. Flatulence, or the passing of gas, is also a common side-effect of the intake of COX-2 inhibitors. This can be an independent occurrence in itself, or exist in a co-relation with some other problems of the digestive system such as nausea and diarrhea. The taking of COX-2 could also be a risk factor for other problems of the digestive system such as ulcers, internal bleeding, and stomach sac perforation. 

Some of the more painful side-effects of taking COX-2 inhibitors is when the drug itself causes more pain and suffering than the original pain itself. Cases like these include headaches and abdominal pains. These medicines also raise the risk of a person undergoing cardiovascular problems like heart arrest and stroke.