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Aspirin belongs to a group of medicines called non-steroidal anti-inflammatory drugs (NSAIDs). It works by blocking the action of a substance in the body called cyclo-oxygenase.
Cyclo-oxygenase is involved in the production of various chemicals in the body. These are known as prostaglandins, prostacyclins and thromboxane. By blocking the action of cylo-oxygenase, aspirin prevents the production of these chemicals.
Aspirin prevents blood cells called platelets from producing thromboxane. Thromboxane is one of the chemicals that causes platelets to clump together and start off the process of blood clotting. Stopping its production reduces the likelihood of clots forming in the blood.
A blood clot that forms inside the blood vessels is known as a thrombosis and can be dangerous, as it can cause a blockage that cuts off the blood supply to an organ. A blockage in the arteries supplying blood to the heart or brain can cause a heart attack or stroke.
Blood clots and blockages mainly result from a build up of atherosclerosis on the inside of blood vessels. Atherosclerosis is a build up of cholesterol and fat cells that narrows the blood vessels and makes their interiors rough and bumpy. This makes it more difficult for blood to flow through the vessels, and increases the likelihood of clots forming in the vessels. People with angina, or who have already suffered a heart attack or stroke, are at risk of having another because of the atherosclerosis in their arteries. Low dose aspirin is used to lower the risk of this.
High doses of aspirin (300mg and over) also prevent the production of prostaglandins. Prostaglandins are produced in response to injury or certain diseases and would otherwise go on to cause pain, swelling and inflammation. High doses of aspirin are therefore used to relieve pain and inflammation. See the factsheets linked below for more information about this use of aspirin.
Aspirin is also used in the emergency situation of a heart attack. Anyone who has the symptoms of a heart attack (chest pain, possibly radiating towards the arm or neck, shortness of breath) should take one 300mg aspirin tablet as soon as possible, as this has been shown to increase the chances of surviving a heart attack. This is because the aspirin prevents the blood clot that is blocking the supply of blood to the heart from growing any bigger. The tablet can be crushed under the tongue for faster absorption into the bloodstream, as the area under the tongue is very rich in blood vessels.
What is it used for?
Warning!
Use with caution in
Not to be used in
This medicine should not be used if you are allergic to one or any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy.
Pregnancy and Breastfeeding
Certain medicines should not be used during pregnancy or breastfeeding. However, other medicines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before using any medicine.
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