US Pharm. 2018;43(2):11-12.

A Little Does a Lot

Aspirin is one of the oldest, most widely used drugs in the world. Taken for pain relief for over 2,000 years, its active ingredient, salicin, is in the leaves and bark of the willow tree. In 1897, the Bayer company in Germany developed a synthetic version called acetylsalicylic acid and named it aspirin. The regular adult dosage is 650 mg taken every 4 hours when needed to treat pain, inflammation, and fever caused by a variety of ailments. Low-dose aspirin refers to dosages between 81 mg and 325 mg taken every day to prevent heart attacks, strokes, and colon cancer.

Prevents Clots From Forming, Growing

Most heart attacks and strokes happen when a blood clot forms and blocks blood flow in an artery. Under normal circumstances, the body develops a blood clot to stop the loss of blood after an injury. When a blood vessel is damaged, sticky cells called platelets begin to clump together, while proteins in the blood form strands of fibrin. The fibrin creates a net-like structure that holds the forming clot together. Blood clots can form in damaged vessels of the heart or the brain, and these can block blood to the tissue and cause a heart attack or stroke. Aspirin stops clots from forming by preventing the platelets from clumping together.

If you have had a heart attack or stroke, your doctor may prescribe low-dose aspirin to prevent a second event. Low-dose aspirin has been shown to reduce the risk of a first heart attack but has not been definitively proven to reduce the risk of a stroke. Speak with your physician before starting low-dose aspirin for prevention.

Anti-Inflammatory Actions Key

Aspirin is also a nonsteroidal anti-inflammatory drug (NSAID), which means that it reduces inflammation, although it is not a steroid like cortisone or prednisone. Similar to the formation of blood clots, inflammation is the body’s natural response to injury. When an injury occurs, the immune system is activated, and compounds called prostaglandins form in the area surrounding the injury. Prostaglandins increase blood flow to the injury, leading to the redness, heat, and swelling associated with inflammation. Aspirin prevents these prostaglandins from forming, reducing inflammation.

It is aspirin’s anti-inflammatory action that also makes it useful in the prevention of colon cancer and in preeclampsia, a serious condition of pregnancy believed to result from an inflammatory response. Recent research has also found regular aspirin use to be associated with lower rates of breast, prostate, lung, and ovarian cancer.

Aspirin Isn’t Right for Everyone

Even in low doses, aspirin can have significant side effects. The most common ones, occurring in up to 10% of people who take aspirin, are an increased tendency to bleed and stomach upset, including heartburn, nausea, vomiting, or bleeding in the stomach. Other less common side effects include kidney, liver, and nervous system problems.

Although low-dose aspirin is an OTC drug and safe for most people, the FDA recommends that certain individuals not take aspirin in any dose. Those with an allergy to aspirin or salicylates; those with a bleeding disorder such as hemophilia or vitamin K deficiency; and people with uncontrolled high blood pressure, severe liver or kidney disease, or asthma should avoid using aspirin. In addition, aspirin should not be used by someone who is also taking a prescription blood thinner such as warfarin, Pradaxa, or Xarelto, or another OTC NSAID such as naproxen (Aleve) or ibuprofen (Advil).

Before taking any OTC drug on a regular basis, even low-dose aspirin, be sure to talk with your healthcare provider first to find out if it’s right for you. Always ask your pharmacist to check your prescription and other OTC medications for aspirin interactions or incompatibilities. Even supplements such as fish oil and vitamin D can interact with aspirin.