Allergy testing

If you suffer with conditions such as eczema or other allergies e.g. to dust mites, pollen etc, you may be more likely to develop a food allergy.

For example, dust mites, mould, pollen, pet dander (tiny flakes shed from skin, fur or feathers), cigarette smoke, dust and food are all possible eczema triggers.

If you suspect you have an allergy, then you should consult your doctor.

If it’s confirmed that you do have an allergy, it means your immune system has reacted to an allergen. The immune system mistakes the allergen as harmful and so it produces antibodies. This is called sensitisation. The next time you eat the same food, the antibodies are ready to react, causing your body to release chemicals which cause a range of symptoms resulting in an allergic reaction.

A food allergy is when the body’s immune system mistakes a particular food, such as nuts and fish, as being harmful. Food allergies are mild in most cases. However they are sometimes serious, and can be fatal. A food allergy is not an intolerance, which can also make you feel unwell but an intolerance is not as harmful as a food allergy.

Common foods which cause allergies are: peanuts, tree nuts ie brazils, almonds, cashews, hazelnuts, walnuts, pecans, fish, shellfish, cows' milk, eggs, soya, wheatCommon foods which cause allergies are:

  • Peanuts e.g. ie brazils, almonds, cashews, hazelnuts, walnuts, pecans
  • Fish
  • Shellfish
  • Cows’ milk
  • Eggs
  • Soya
  • Wheat

There is a possibility that someone allergic to peanuts may also be allergic to other nuts. If you are allergic to a non-food item e.g. pollen, you may find that your allergic reaction crosses over and you experience a reaction with some foods. This is called cross-reactivity.


  • Itchy or swollen lips, mouth, tongue and throat
  • Skin reactions (e.g. swelling and itching, a rash around your mouth, eczema and flushing)
  • Wheezing or shortness of breath
  • Diarrhoea, feeling sick, vomiting and bloating
  • Coughing
  • A runny nose
  • Sore, red and itchy eyes

These symptoms may not necessarily be caused by food. However, they may be a reaction to pollen, pet dander, mould etc. Whatever the cause, if you experience an allergic reaction you should seek advice from your GP.

It is possible that if you experience a severe reaction you will go into anaphylaxis or experience an anaphylactic shock.

Anaphylaxis is a rare but potentially fatal allergic reaction. Symptoms can include dizziness, a rapid pulse, losing consciousness, a drop in blood pressure and swelling of the airways and throat making it difficult to breathe.

Anaphylaxis can become very serious if not treated quickly – you should call 999 immediately if you suspect an anaphylactic shock is taking place.

Between August and November 2017, talkhealth carried out a survey around the relationship between eczema and allergies, and anaphylactic shock – find out more here.

Treatment of allergies

Your doctor may refer you to a specialist allergy clinic for tests. These tests may include the following:

  • Skin prick tests
  • Patch testing
  • Elimination diets
  • Blood tests

Patch test: this is used to see if a skin reaction, for example eczema, is caused by contact with specific chemical or substance.Skin prick test: usually the first test to be done when looking for an allergen. It is painless, safe and quick. The skin is pricked with a tiny amount of the suspected allergen to see if there is a reaction. If there is, the skin around the prick will very quickly become itchy, and a red circle will appear.

Patch test: this test is used to see if a skin reaction, for example eczema, is caused by contact with a specific chemical or substance, such as household cleaning products. A small amount of the suspect substance or chemical, such as nickel, is added to special metal discs, which are taped to your skin for 48 hours.

Elimination diet: this is a test to see which foods your body reacts to. It may mean excluding certain foods for a period of time with the guidance of a healthcare professional. By carrying out this test, the clinic, GP or hospital is soon able to determine which foods you should to avoid.

Blood tests: this is a specific IgE test (formally known as the RAST test). It measures the amount of IgE antibodies in your blood that have been produced by your immune system in response to a suspected allergen.

Knowing what you are allergic to is key to managing your condition.

For more information on allergies, testing, treatments and details of NHS allergy clinics, go to NHS Choices ( and search ‘allergies’.

Remember: if someone has a serious reaction, call 999 immediately.

Sources used in writing this article are available on request

Information contained in this Articles page has been written by talkhealth based on available medical evidence. Our evidence-based articles are certified by the Information Standard and our sources are available on request. The content is not, though, written by medical professionals and should never be considered a substitute for medical advice. You should always seek medical advice before changing your treatment routine. talkhealth does not endorse any specific products, brands, or treatments.

Information written by the talkhealth team

Last revised: 21 November 2017

Next review: 21 November 2020