Aspirin is an antiplatelet medicine, which means it reduces the risk of clots forming in your blood. This reduces your risk of having a stroke or heart attack.
Normally, when there is a cut or break in a small blood vessel, a blood clot forms to plug the hole until the blood vessel heals.
Small cells in the blood called platelets make the blood clot. When a platelet detects a damaged area of a blood vessel, it produces a chemical that attracts other platelets and makes them stick together to form a blood clot.
Aspirin reduces the ability of the platelets to stick together and reduces the risk of clots forming.
When is low-dose aspirin used?
Low-dose aspirin (usually 75mg a day) may be given to you if you have had:
•a heart attack
•a stroke or transient ischemic attack (TIA)
•acute coronary syndrome (minor heart attack or unstable angina)
•a coronary artery bypass operation
•a bioprosthetic heart valve
•a vascular operation
•a stent put into any one of the arteries in your body
It may also be given to you if you are considered at risk of having a heart attack or stroke. You may be considered at risk if you:
•have high cholesterol
•have high blood pressure
Treatment with an antiplatelet medicine such as aspirin is usually for life.
Higher doses of aspirin may be given for other conditions, but these pages focus on the use of low-dose aspirin.
Aspirin may be given to children under specialist supervision after heart surgery, or to treat children with Kawasaki disease.
Aspirin must not be given to anyone under 16 years old, unless under specialist advice.
Things to consider
You should not take aspirin if you have certain health conditions, such as a peptic ulcer or bleeding disorder.
You should also use aspirin with caution if you have certain conditions, such as asthma or uncontrolled high blood pressure.
Low-dose aspirin (75mg) may be taken if you are pregnant or breastfeeding, but only on the recommendation of your GP.
Read more detailed information about things to consider before taking aspirin.
Side effects and interactions
Although serious reactions are rare, aspirin can cause side effects such as indigestion. In more serious cases it can cause vomiting, an allergic reaction or bleeding in the stomach.
See your doctor if you are worried or continue to experience any side effects while taking low-dose aspirin.
Read more information about the side effects of aspirin.
Aspirin can interact with many other medicines. Always read the patient information leaflet that comes with your medicine to check that it is safe to take with aspirin. If you are unsure, ask your pharmacist or GP.
Read more information about other medicines that can interact with aspirin.
If you forget to take your dose of aspirin, take that dose as soon as you remember and then continue to take your course of aspirin as normal.
However, if it is almost time for the next dose, skip the missed dose and continue your regular schedule. Do not take a double dose to make up for a missed one.
The patient information leaflet that comes with your medicine includes advice about what to do if you miss a dose.
If you accidentally take an extra dose of low-dose aspirin, it is unlikely to cause you harm as larger doses of aspirin are given safely for other conditions.
However, if you feel unwell or are concerned, speak to your GP or pharmacist, or call NHS 111.
Last updated: 09 November 2015
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