Aspirin, also known as acetylsalicylic acid (ASA), is a nonsteroidal anti-inflammatory drug (NSAID) used to reduce pain, fever, and/or inflammation, and as an anticoagulant. Specific inflammatory conditions which aspirin is used to treat include Kawasaki disease, pericarditis, and rheumatic fever.Aspirin is also used long-term to help prevent further heart attacks, ischaemic strokes, and blood clots in people at high risk. For pain or fever, effects typically begin within 30 minutes. Aspirin works similarly to other NSAIDs but also suppresses the normal functioning of platelets.One common adverse effect is an upset stomach. More significant side effects include stomach ulcers, stomach bleeding, and worsening asthma. Bleeding risk is greater among those who are older, drink alcohol, take other NSAIDs, or are on other blood thinners. Aspirin is not recommended in the last part of pregnancy. It is not generally recommended in children with infections because of the risk of Reye syndrome. High doses may result in ringing in the ears.A precursor to aspirin found in the bark of the willow tree (genus Salix) has been used for its health effects for at least 2,400 years. In 1853, chemist Charles Frédéric Gerhardt treated the medicine sodium salicylate with acetyl chloride to produce acetylsalicylic acid for the first time. Over the next 50 years, other chemists established the chemical structure and devised more efficient production methods. : 69–75 Aspirin is available without medical prescription as a proprietary or generic medication in most jurisdictions.
Similarly, the results of the ARRIVE study also showed no benefit of same dose of aspirin in reducing the time to first cardiovascular outcome in patients with moderate risk of cardiovascular disease over a period of five years.Aspirin appears to offer little benefit to those at lower risk of heart attack or stroke—for instance, those without a history of these events or with pre-existing disease. Some studies recommend aspirin on a case-by-case basis, while others have suggested the risks of other events, such as gastrointestinal bleeding, were enough to outweigh any potential benefit, and recommended against using aspirin for primary prevention entirely. Aspirin has also been suggested as a component of a polypill for prevention of cardiovascular disease.Complicating the use of aspirin for prevention is the phenomenon of aspirin resistance. For people who are resistant, aspirins efficacy is reduced. Some authors have suggested testing regimens to identify people who are resistant to aspirin.After percutaneous coronary interventions (PCIs), such as the placement of a coronary artery stent, a U.S. Agency for Healthcare Research and Quality guideline recommends that aspirin be taken indefinitely. Frequently, aspirin is combined with an ADP receptor inhibitor, such as clopidogrel, prasugrel, or ticagrelor to prevent blood clots. This is called dual antiplatelet therapy (DAPT). Duration of DAPT was advised in the United States and European Union guidelines after the CURE  and PRODIGY  studies . In 2020, the systematic review and network meta-analysis from Khan et al.