You probably have it tucked away in your medicine cabinet. Whether you’re taking it to stave off the aches and pains of daily life or reduce your risk of a cardiovascular event, aspirin has been a staple for over a century. But what is it, and how does it work in the body? 

What is Aspirin?

Aspirin is made from salicylic acid, an organic compound found in a common shrub called Spiraea. The white willow tree’s bark also contains the drug’s natural element. It’s been used naturally for thousands of years. The ancient Egyptians used it for joint pain, and Hippocrates recommended it for childbirth.

In 1763, the British scientist Edward Stone conducted the first experiments to show the power of willow bark. Writing in the Journal of the Royal Society of Medicine, he said that he had uncovered a miracle drug in the bark of an English tree. “I have found [it] by experience to be a powerful astringent and very efficacious in curing aguish and intermitting disorders.”

A century later, in 1874, the British physician Thomas MacLagan used salicin, the active ingredient in aspirin, on his patients with rheumatic fever. After gradually increasing the dosage on himself to check for its safety, MacLagan began giving it to his patients. His accounts are published in the Journal of the Royal Society of Medicine.

“The sudden arrest of the painful symptoms, and the coincident rapid fall of pulse and temperature, followed so immediately on the administration of the salicin that it is impossible not to attribute them to its use.”

Read More: Prehistoric Medicine: How Archaic Humans Cured Themselves

How Does Aspirin Work?

While aspirin seems like a basic remedy, its impact on the body is complex. We feel pain once trauma in the body transmits signals of that pain to the brain. Lipids produced from pain in the cells enter an enzyme called cyclooxygenase which then causes the production of prostaglandins, a group of lipids similar to hormones that create and regulate pain and inflammation at the site of tissue damage or infection.

Inside the enzyme, these lipids form pain messenger substances that fit into pain receptors on the nerve endings and then transmit pain signals to the brain. Aspirin is a member of a class of drugs known as nonsteroidal anti-inflammatory drugs (NSAIDs) that work by blocking the enzyme that causes inflammation so that it can’t produce pain messengers. 

Aspirin for Blood Clots

The drug is also a powerful tool for reducing your risk of blood clots. Blood clots form when fibrin, strands of protein that form a net in the blood vessels, begin to gather, causing platelets and cells to clump and get caught in the net. In this case, aspirin interrupts the formation of clotting.

This can form a clot, but aspirin makes cells and platelets less sticky, so they don’t clump together and block the arteries. However, you should not take aspirin daily unless you’re at an increased risk of cardiovascular events and your doctor has recommended it. The medication can decrease the clotting ability in some people and increase their risk of bleeding.

Aspirin is a wonder drug that has been around for thousands of years naturally and in its current form for a century. And while we might not have always understood the mechanism for how it worked in the body, we’ve long known that it was effective. From joint pain to fever and anti-clotting, you don’t have to know why it works to know that it does.

Read More: Despite Dangers, Millions of Americans Are Still Taking Daily Aspirin