About aspirin

Aspirin is a common medicine that has many uses. It can relieve pain and reduce the risk of serious problems like heart attacks and strokes.

It comes in many forms, including:

  • pills
  • powders
  • oral gels
  • soluble tablets

Some types of aspirin can be bought over the counter from pharmacies. Others are only available on prescription.

What aspirin is used for

At high doses (usually 300mg) aspirin can:

  • relieve pain
  • reduce a high temperature (fever)
  • reduce swelling

It's often used for short-term relief from:

Long-term treatment with low doses of aspirin (usually 75mg) has an antiplatelet effect. This means it makes the blood less sticky and can stop blood clots developing.

A doctor may recommend this if you have or have had:

Aspirin may also be prescribed for children after heart surgery or to treat Kawasaki disease. It shouldn't be given to anyone under 16 years old without medical supervision.

Who can and can't take aspirin?

Most people can take aspirin safely. However, you should get advice from a pharmacist or doctor before taking it if you:

  • have ever had an allergic reaction to aspirin
  • have ever had an allergic reaction to non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen
  • have asthma
  • have had stomach ulcers in the past
  • have severe liver problems
  • have severe kidney problems
  • have haemophilia or another bleeding disorder
  • have uncontrolled high blood pressure
  • are looking for medication for a child under 16 – medication containing aspirin shouldn't be given to children under 16
  • are over 65 years of age
  • are pregnant, breastfeeding or trying to get pregnant
  • are taking other medications

You may still be able to take aspirin in these cases. However, you should only do so if advised that it's safe by a healthcare professional.

If you can't take aspirin, a different medicine may be recommended. This could include paracetamol (for pain) or clopidogrel (to prevent blood clots).

How to take aspirin

Your pharmacist or doctor can tell you how often to take your aspirin and how much you should take. You can also check the recommendations in the leaflet that comes with your medicine.

Generally speaking:

  • high-dose aspirin (to relieve pain) can be taken 3 or 4 times a day, with at least 4 hours between each dose, until your symptoms improve
  • low-dose aspirin (to prevent blood clots) is taken once a day, usually for the rest of your life

Some medicine leaflets advise you to take aspirin with water. Others may recommend taking it with or after food.

Accessing medicines self-help guide

Visit our self-help guide on accessing medicines if you have difficulty getting the medicines you need.

Self-help guide: Accessing medicines

Side effects of aspirin

Like all medications, there's a risk of side effects from aspirin.

The most common side effects are:

  • indigestion and stomach aches – taking your medicine with food may help reduce this risk
  • bleeding or bruising more easily than normal

Speak to your doctor or pharmacist if you experience any concerning or troublesome side effects while taking aspirin.

Urgent advice: Phone 999 or go to A&E if:

You are taking aspirin and have symptoms like:

  • hives – a raised, itchy rash
  • tinnitus – hearing sounds that come from inside your body
  • breathing difficulties or an asthma attack
  • an allergic reaction – this can cause breathing problems, swelling of the mouth, lips or throat, and a sudden rash
  • severe headaches
  • vision problems
  • stroke symptoms, like slurred speech or weakness on one side of the body
  • dark-coloured stools (poo)
  • rapid breathing
  • vomiting
  • blood in vomit
  • sweating
  • dizziness

Interactions with other medicines, food and alcohol

Aspirin can interact with other medications, including some complementary and herbal medicines. This could alter their effects or increase your risk of side effects.

Medicines that can interact with aspirin include:

  • NSAIDs – like ibuprofen or naproxen
  • steroid medication – like prednisolone
  • anticoagulant medicines – like warfarin or heparin
  • SSRI antidepressants – like citalopram, fluoxetine or paroxetine
  • some medications used to treat high blood pressure – like ACE inhibitors or diuretics
  • some medicines used to treat epilepsy – like phenytoin
  • other medicines containing aspirin – including cold and flu remedies where aspirin is one of the ingredients

This is not a complete list. If you want to check whether a medicine is safe to take with aspirin, ask your doctor or pharmacist. You should also read the leaflet that comes with the medicine.

There are no known interactions between aspirin and food.

The risk of bleeding in the stomach may be higher if you drink alcohol while taking aspirin. You may want to consider reducing how much you drink or avoiding alcohol completely.

Missed or extra doses

If you're taking aspirin to reduce your risk of blood clots and you forget to take a dose, take that dose as soon as you remember. You should then continue to take your course of aspirin as normal.

If it's almost time for the next dose, skip the missed dose and continue your regular schedule. Don't take a double dose to make up for a missed one.

Non-urgent advice: Speak to your GP or pharmacist if:

  • you think you've taken too much aspirin (an overdose) and have any concerns

If your GP or pharmacy are closed, phone 111 for advice.

Last updated:
16 December 2022