Aspirin (USAN), also known as acetylsalicylic acid (ASA), is a salicylate drug, often used as an analgesic to relieve minor aches and pains, as an antipyretic to reduce fever, and as an anti-inflammatory medication.
Low-dose, long-term aspirin use irreversibly blocks the formation of thromboxane A2 in platelets, producing an inhibitory effect on platelet aggregation. This anticoagulant property makes aspirin useful for reducing the incidence of heart attacks. 40 mg of aspirin a day is able to inhibit a large proportion of maximum thromboxane A2 release provoked acutely, with the prostaglandin I2 synthesis being little affected; however, higher doses of aspirin are required to attain further inhibition. (Nebe, J; Heier, M; Diener, HC (1995). "Low-dose ibuprofen in self-medication of mild to moderate headache: a comparison with acetylsalicylic acid and placebo". Cephalalgia : an international journal of headache 15 (6): 531-5.)
Low-dose aspirin decreases the risk of heart attack in patients with chronic stable angina, and was previously part of standard treatment, however it has since been discovered that the increase in hemorrhagic stroke and gastrointestinal bleeding offsets this gain so they are no longer advised unless the risk of myocardial infarction is very high. (Barnett H, Burrill P, Iheanacho I. (April 2010). "Don't use aspirin for primary prevention of cardiovascular disease". BMJ 340: c1805. doi:10.1136/bmj.c1805. PMID 20410163)
Aspirin is an antiplatelet medicine, which means it reduces the risk of clots forming in your blood. Low-dose aspirin (usually 75mg a day) may be given to you if you have had:
a heart attack
a coronary artery bypass operation
acute coronary syndrome (minor heart attack or unstable angina)
It may also be given to you if you are considered to be at risk of having a heart attack or stroke.
It has been well documented that aspirin reduces the risk of heart attack in people with known coronary artery disease (CAD). It is also now understood that aspirin lowers the risk of having symptoms for people who have a higher risk for the disease. People who are at high risk for coronary artery disease or who already have coronary artery disease benefit the most from aspirin therapy.
A new study in the Lancet medical journal adds to a growing body of evidence suggesting that a daily dose of aspirin can reduce the risk of dying from several types of cancer, with even low-dose aspirin appearing to be beneficial. The benefits were strongest for bowel, oesophageal and stomach cancers. Aspirin could also help to prevent deaths from pancreatic, lung and brain cancers. The researchers believe that patients may gain the most benefit by starting to take aspirin in their late 40s or 50s, when the risk of developing many cancers begins to rise.