Allergy Testing

Skin Prick Allergy TestingHow are allergies tested for?

There are three methods of reliable allergy testing available.

Skin Prick Allergy Testing and IgE specific blood testing can be used to identify allergies to a wide range of airborne allergens and foods. 

Patch testing is used specifically to help identify contact allergic triggers in a condition called contact dermatitis.

Skin prick allergy testing is the principal method of allergy testing as it carries a number of advantages over IgE specific blood testing. It is used in Allergy Ireland and all other major allergy centres.

Skin Prick Allergy Testing

What is Skin Prick Allergy Testing?

Skin Prick Allergy Testing is a safe, fast and virtually painless investigation which identifies whether a suspected allergy is present. It is performed in clinic and the results are available within 15 minutes. It is vital that the results are interpreted by an expert. Allergy Testing in Allergy Ireland is immediately followed by consultation with one of our doctors who will accurately interpret the results and tailor a management plan.

In cases where a food challenge is under consideration then occasionally both skin prick allergy testing and IgE specific bloods tests are carried out. This depends on the specific case history.

Is Skin Prick Allergy Testing Accurate?

Yes, Skin Prick Allergy Testing is a very accurate. It is a very sensitive test with a sensitivity of 95% which results in a low rate of false negatives. This means that it is very unlikely for the allergy to be present if the test is negative. Thus, the negative predictive value is very strong.

The specificity of skin prick allergy testing ranges from 50-70% depending on the allergen being tested. This means that false positives are possible and explains why it is vital that the results are interpreted by an expert in the context of a detailed clinical history and examination. 

What conditions is Skin Prick Allergy Testing useful for?

Skin Prick Allergy Testing is used to confirm sensitisation in IgE mediated allergic disease. This is important in:

  • Food Allergy and Anaphylaxis
  • Allergic Rhinosinusitis and Allergic Conjunctivitis
  • Asthma
  • Eczema
  • Chronic Urticaria

Skin Prick Allergy Testing multistickWhat does Skin Prick Allergy Testing involve?

Skin Prick Allergy Testing involves placing a small droplet of allergen onto the skin and then introducing a tiny amount of each allergen into the skin. If allergic sensitisation is present, then a temporary bump called a wheal will form on the skin and the surrounding skin will flare red. There are positive (histamine) and negative (saline) controls to ensure the accuracy of test result.

Which allergens can Skin Prick Allergy Testing test for?

Skin Prick Allergy Testing can test for a very wide range of airborne allergens and foods.  

The following allergens can be tested for at Allergy Ireland: 

  • Inhalant Allergens: House Dust Mite, Pollen (Grass/Tree/Ragweed), Feathers, Animal Dander (Cat/Dog/Horse/Rabbit) and Household Mould Spores (Alternata & Cladosporium).
  • Common Foods: Egg, Milk, Soya, Wheat, Potato, Tomato, Strawberry, Kiwi, Orange and Chocolate (Cocoa).
  • Nuts/Seeds (where appropriate):  Peanut, Almond, Cashew nut, Hazelnut, Brazil nut, Walnut, Pecan, Pine nut, Pistachio, Chestnut, Sesame seed, Sunflower seed.
  • Fish/Shellfish (where appropriate): Cod, Hake, Salmon, Tuna, Mackerel, Prawn, Lobster, Crab, Oyster, Mussels, Scallops.

If you would like to be tested for something not listed above please contact us by e-mail. For example, if you bring a small sliver of fresh food then this can be tested directly. This is usually done for specific fish you suspect you may have reacted to if it is not available in allergy extract form. 

Can Skin Prick Allergy Testing be used to test for food intolerances?

No, Skin Prick Allergy Testing can not be used to test for food intolerances. Food intolerances do not involve an immune response so there is no medical test that can be used for detection. We recommend exclusion of the suspected food followed by reintroduction in order to check for food intolerance. This is best done under the guidance of a dietition.

Skin Prick Allergy Test Result Interpretation

It’s easy to perform an allergy test, the skill lies in interpreting the result in the context of the patient's symptoms. Sometimes there is no link.

What are the requirements for Skin Prick Allergy Testing?

  • Anti-histamines must not be taken starting 5 days prior to the testing date. This includes oral antihistamines and topical antihistamine nasal sprays (Ryaltris, Dymista) and antihistamine eye drops (Opatanol). 
  • Skin Prick Testing should not be carried out within 4 weeks of a systemic allergic reaction or anaphylaxis. This is due to the risk of false negative test results.
  • Skin Prick Testing should be avoided during pregnancy due to the remote risk of a reaction triggering early labour.
  • Steroid creams should not be applied to the area of skin being used for testing within 24 hours prior to the test.

Patch Testing

What is Patch Testing used for?

Patch Testing is used to detect allergic triggers in a condition called Contact Dermatitis. It does not test for food or inhalant allergies. 

What does Patch Testing test for?

Patch Testing tests for common chemicals in our daily environment and workplaces that cause skin reactions when they come in contact with some peoples skin. They include cosmetics, hair dye, fragrances, sun cream, lanolin, dental metals and adhesives. These reactions only occur in sensitised individuals. 

Further Information on Patch Testing