How Does Aspirin Work?


Quick Answer

Aspirin works by preventing the human body from producing prostaglandins. Prostaglandins are natural chemicals with many roles in the body, including sending pain messages to the brain, causing blood to clot and keeping the stomach lining thick and healthy.

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Full Answer

When a part of the body becomes injured, an enzyme called cyclooxygenase-2, or COX-2, starts to produce prostaglandins. These prostaglandins amplify the pain signals that are sent to the brain from the injured body part. They also cause large amounts of blood to be sent to the injured area to immobilize it and help it heal, which causes inflammation or swelling. HowStuffWorks explains that aspirin works by sticking to the enzyme COX-2 and preventing it from producing prostaglandins. Since fewer prostaglandins are being made, the pain signal sent to the brain is less intense and the amount of swelling is lessened as well.

Another function of prostaglandins is to cause small cells in the blood called platelets to stick together in order to create blood clots. Blood clots are very helpful when someone has a cut or a bloody nose, but they can be dangerous when the clot happens inside a blood vessel. In this instance, blood clots can cause a heart attack. When aspirin binds to COX-2, it also prevents the creation of prostaglandins that cause blood clotting. According to WebMD, this is why doctors may recommend low doses of aspirin to prevent blood clots in patients at risk for stroke and heart attack or those who have recently undergone medical procedures such as bypass surgery or a coronary stent.

One drawback to aspirin is that it also binds to a similar enzyme in the body called cyclooxygenase-1, or COX-1, which produces the prostaglandins that keep the stomach lining thick and healthy. When someone consumes aspirin at a high dose for too long, COX-1 is prevented from making the prostaglandins that maintain the stomach lining. As a result, the lining can become thin and easily irritated by the digestive juices in the stomach. This can lead to some of the common side effects of aspirin listed by the National Institute of Health, such as nausea, vomiting, stomach pain and heartburn.

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