For more than 100 years, aspirin has been used as a pain reliever for headaches and other minor aches and pains. According to the U.S. Food and Drug Administration (FDA), Americans consume more than 20 billion tablets a year.

More recently, aspirin has been widely studied in terms of preventing cardiovascular disease and managing the conditions of people who already have heart disease or a history of heart attack. Some of these research findings include:

In 2002, researchers concluded that aspirin can reduce the risk of a first heart attack by 32 percent and reduce the combined risk of heart attack, stroke and vascular death by 15 percent. The findings supported the American Heart Association's (AHA) position that aspirin should be recommended for all men and women whose 10-year risk of a first coronary event is 10 percent or greater.

In 2007, the AHA altered its guidelines to state that all women over the age of 65 should start a low-dose regimen of aspirin, regardless of their risk profile. It is thought that this step, in addition to other lifestyle changes, may improve the lifetime risk of heart disease in women. Previous guidelines had suggested that low-risk and healthy women did not need to take aspirin on a regular basis.

However, the AHA and the FDA strongly urge patients to discuss aspirin therapy with their physician. According to the FDA, many people mistakenly believe they can safely take aspirin every day because it is an over-the-counter medication. This misperception leads to more than 100,000 hospitalizations every year due to the overuse of aspirin and other over-the-counter pain medication.

Studies have found different dosages to be beneficial. Many studies suggest a low daily dose of aspirin (81 milligrams [mg]) to be effective in the prevention of heart attack and stroke. Other studies have used regular doses of aspirin (325 mg). Generally, there is no additional benefit in taking more than 325 mg a day, and dosages under 70 mg have been shown to be ineffective.

Aspirin can be taken orally in tablets or capsules with an enteric coating, which is gentler to the stomach. Aspirin may also be taken in the form of chewing gum or suppositories.

Patients who are taking aspirin for its heart benefits should be aware that taking ibuprofen (a type of nonsteroidal anti-inflammatory drug [NSAID]) at the same time to relieve pain may limit the effectiveness of aspirin. Although these two medications can be used together safely, patients should consult their physician about the timing of aspirin doses to ensure they receive the full benefit of both drugs.

The main pain-relieving chemical in aspirin (salicin) has been used for pain relief since the 5th century B.C. People such as the famous physician Hippocrates discovered that chewing willow bark and leaves, or using them to brew a potion, could help to relieve pain. It was not until the 1800s that researchers were able to identify salicin as the chemical responsible for the pain relief.

After struggling to find a way to offer the benefits of salicin without its stomach-burning properties, aspirin was first presented to the public in 1915. The manufacturing company was Bayer, a German company that lost its patent as part of the Versailles Treaty that ended World War I. Aspirin got the first letter of its name from the chemical used to make salicin gentler to the stomach (Acetyl chloride). The next four letters came from the plant from which the salicin was derived: Spirea ulmaria. The last two letters represent the common ending of drug names at the time: in. Aspirin is now one of the most widely used drugs around the world. No other pain killer provides the health benefits of aspirin.