How does the pain killer Aspirin work inside the body?

Aspirin has been in the market since 1899, relieving people’s pains, fevers and inflammation. Scientific research has shown that the drug works because it affects the body’s production of prostaglandins. These substances, produced in response to stress, are in a way, opposites of aspirin: they heighten pain and stimulate fever and inflammation.

Ordinarily, prostaglandins have desirable effects. When a pin pricks you, for example, your skin takes particular notice, since prostaglandins sensitize nerves that carry pain impulses to the brain. And if you get an infection from the pin prick, these substances help to increase the body temperature to fight the invading micro-organisms. Further, prostaglandins dilate blood vessels in the infected area, allowing more blood to come in to aid healing. This often causes inflammation.

Aspirin or acetylsalicylic acid bonds with an enzyme that helps produce prostaglandins, preventing it from doing its work. With reduced prostaglandin production, pain, fever and inflammation ease. Research also shows that part of aspirin’s pain killing power comes simply from the placebo effect – the user’s belief that aspirin will in fact bring relief. Aspirin also reduces blood clotting, an additional property that could prevent cardiovascular diseases.

However, prostaglandins only have a portion to play when it comes to the total signal for the pain sent to the brain, but it is an important one. Not only does it help you by telling you that you are hurt but also results in inflammation. It is a process where your damaged finger or any other body part becomes swelled. This is actually done to bathe your tissues in fluid from your blood so that it remains protected and is allowed to heal. Overall, when it comes to one feeling pain, there are a lot of chemicals involved in the process other than prostaglandins.

Additionally, people do not only feel hurt or pain when they cut their body parts only, but there are some cases where people go through headaches, stomach pains and arthritis, etc. Women additionally experience stomach pain and cramps when they are on their periods. In such cases as well, the prostaglandins have a role too. Aspirin helps you with these problems by forcing the cells to stop the production of prostaglandins. On the other hand, COX-2 is also found in majority normal tissues, to which aspirin attaches itself and will not allow it to perform its job. So with aspirin stuck to COX-2, it does not actually eliminate the pain but helps in reducing the volume level of pain signals that are sent to your brain through the nerves.

A common question people ask is, how does aspirin know which area is hurt? The answer is that it doesn’t. When you consume an aspirin, it goes down into your stomach or digestive tract and gets absorbed by the body. From there, it makes its way to the entire body through the bloodstream, not affecting the regular body parts but only the area where prostaglandins are being made. After it has been inside your body for around 5 to 6 hours, other organs will change it into Salicylic acid. The liver then will change it a bit more and stick it to other chemicals so that your kidneys are able to filter the aspirin from your blood and send it out through urine. That is why you need to take another aspirin after 5 to 6 hours because it has performed its primary function.

Lastly, prostaglandins are not always bad. They are present in your stomach, brain, and kidneys as well. In the stomach, for instance, there is another enzyme known as COX-1 that produces prostaglandins, helping the lining of the stomach to remain nick and thick. Even though, the normal dosage of aspirin won’t hurt much, but over time it can make this stomach lining thin, which can cause irritation in the digestive system.