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Aspirin intolerance and salicylates

Aspirin is one of the oldest medicines known, and is common in many traditional medicine remedies including Chinese medicines. Aspirin was originally extracted from plants but is now made synthetically. A number of similar medicines have now been produced, and this group of medicines is known as Non-Steroidal Anti-Inflammatory Drugs or NSAIDs. Other NSAIDs are naproxen and ibuprofen (Nurofen).


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NSAIDs can be very effective medicines for pain and fever. They work by inhibiting the production of compounds in the body which are involved in tissue inflammation and fever. Aspirin also ‘thins’ the blood by interfering with the ability of the blood to clot, and is used by health professionals in those at risk of heart attacks and strokes. There is also emerging evidence that aspirin may even reduce the risk of certain cancers.

Like all medicines, aspirin and NSAIDs have side effects. Common side effects include bruising and stomach upset (or even ulcers or bleeding from the bowel), at high dose. Very high doses may cause confusion or ringing in the ears (tinnitus). Aspirin should not be used in children, as it can trigger severe liver damage (known as Reye's syndrome). Ibuprofen (Nurofen) and other NSAIDs are safe to use in children.

Allergy to Aspirin

Some people develop allergic reactions to aspirin. Symptoms usually happen within an hour of taking the medicine, and can be mild (such as hives or nettle rash, blocked or runny nose) to severe reactions affecting the breathing. Most people allergic to aspirin or another NSAID will not react to other NSAIDs, but up to 20% can react to other drugs in the group. It is therefore important to discuss what drugs to avoid with your doctor.

Be careful, because aspirin is present in many different types of medicine and it may not always be obvious. Medicines which can contain aspirin include:

  • cold & flu remedies
  • medicines used for pain from headache, periods, sinus
  • some antacids
  • drugs used for inflammatory bowel disease
  • many complementary and alternative medicines, especially those used for pain and joint problems
  • Teething gels 

If you are sensitive to aspirin, you will need to carefully read medicine labels. Always check with your doctor or pharmacist first.

People who suffer from hives (urticaria), nose / sinus problems or asthma are often more at risk of aspirin allergy than people who do not have these conditions.

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What is aspirin desensitisation?

Some people with nasal polyps and asthma can be particularly sensitive to aspirin. It is possible to desensitise these people, as well as people with aspirin allergy. This involves giving very small but increasing doses of aspirin over a period of time, to teach the body to tolerate the drug. This should only be done by doctors experienced in aspirin desensitisation.

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What about salicylates in food?

Naturally occurring salicylates are found in a wide variety of plant foods and bacteria, and include methyl-salicylate and other salicylate salts. Some researchers have suggested that foods rich in naturally occurring salicylates can cause symptoms of intolerance, and recommend an exclusion diet. However, there is actually quite limited data that this is true, and almost all people with asthma are able to eat foods rich in salicylate without a problem.

This may be because aspirin contains a special molecule called an acetyl group, while naturally occurring salicylates are mostly non-acetylated. Aspirin can trigger symptoms in some people with urticaria, but whether foods naturally high in salicylate can do the same is very unclear.

Occasionally, people who are allergic to aspirin and have asthma, nasal polyps and sinusitis/rhinitis will suffer symptoms if they eat foods that have high levels of natural salicylates in some food. This affects the occasional person rather than the majority, so low salicylate diets are not considered a routine part of management.

The best way to find out whether salicylates in food are causing symptoms is by avoiding high salicylate foods for two-four weeks and seeing if things improve. Foods containing high levels of salicylate include tea (except fruit and camomile tea), coffee, dried herbs and spices, black pepper, sharp green apples, cherries, strawberries, dried fruit, tomatoes (fresh, puree and ketchup), fruit juices, cider, wine, peppermints and liquorice. If this diet has made no difference to your symptoms you should re-introduce all the foods. This is important as salicylates in foods may be important for the prevention of cancer and heart disease. If the exclusion of these foods has been helpful and you wish to continue, you should seek the advice of a qualified dietitian who can provide advice as to what foods to avoid while ensuring that the diet you can eat is nutritionally adequate.

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Last updated: July 2013                 Next Review date July 2015
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