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)
- atrial fibrillation
- a coronary artery bypass operation
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:
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
If you have certain health conditions such as a peptic ulcer or bleeding disorder you should not take aspirin.
Low-dose aspirin (75mg) may be taken if you are pregnant or breastfeeding, but only on the recommendation of your GP.
Read more information about things to consider before taking aspirin.
Although serious reactions are rare, aspirin can cause side effects including indigestion and nausea. In more serious cases it can cause vomiting, bleeding or an allergic reaction,
Read more information about the side effects of aspirin.
Aspirin can also interact with 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 how aspirin interacts with other medication.
Missed or extra doses
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.
If you have to take two doses closer together than normal, there is an increased risk of side effects.
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 Direct on 0845 46 47.