Aspirin (acetylsalicylic acid) is an anti-inflammatory pain killer (NSAID), which is extensively used, worldwide, for pain relief, to reduce inflammation and temperatures, and to reduce the risk of heart attacks and strokes.

• Pain relief, particularly where there is inflammation involved, including dental pain and period pain (dysmenorrhoea).
• Reducing temperature (as an antipyretic).
• Making the blood flow better through narrowed blood vessels.

Aspirin works, like the other NSAIDs, to reduce inflammation and pain, by affecting the prostaglandins. It also makes some small particles in the blood, known as platelets, less sticky, which makes the blood less likely to form blood clots in narrowed blood vessels. It is thus widely used to prevent heart attacks and strokes. For this effect a tiny dose is all that is needed (75-150mg daily).

Aspirin is also very good at bringing down temperatures in people who have an elevated temperature (fever).

The most common unwanted affect is indigestion, and so it should not be used (except on medical advice) in someone who has a peptic ulcer or has had one in the past.

Also as a result of this side effect, it should be used with caution, if at all, in somebody prone to heartburn or indigestion. It is best to take aspirin after food.

Skin rashes occur in some people, and sometimes with dramatic swelling of the face and mouth and difficulty breathing (anaphylactic reaction).

A very rare, but serious condition in children (Reye's Syndrome) is believed to be more likely to happen in children who have taken aspirin for mild viral symptoms. As a result, aspirin is no longer used routinely in children below the age of 16 years or for breast feeding mothers.

There is a condition known as G6P-Deficiency, which causes a severe form of anaemia, where the red blood cells are broken down, when people with that particular condition eat certain products or drugs, for example fava beans. Aspirin causes a reaction in these people, and must be avoided.

Aspirin must not be used by anyone with known allergy to aspirin, or who has a bleeding disorder, or who is taking blood thinning drugs (anticoagulants).

Always read the leaflet that comes with any medication.

• Tablets, including soluble tablets.
• Coated tablets, which partly protect the stomach from direct irritation. These take longer to work, and are therefore of less value for fast-acting pain relief. They can be ideal for regular use to protect against heart attacks and strokes.
• Other forms are rarely used in the UK.

• Aspirin: A century of good news (BBC News, 26 Jun 2002)