Allergy Testing

Skin Prick Allergy Testing

How do you test for allergies?

There are three main methods of reliable allergy testing available. Skin Prick Allergy Testing and IgE specific blood testing are used to identify allergies to a wide range of airborne allergens and foods. Patch testing is used specifically to identify the contact allergic trigger in a condition called contact dermatitis.

Skin prick allergy testing is regarded as the gold standard allergy testing method as it carries a number of advantages over IgE specific blood testing. It is therefore used in Allergy Ireland and other major centres such as the Department of Paediatric Allergy at CHI Crumlin.  

Skin Prick Allergy Testing

What is Skin Prick Allergy Testing?

Skin prick testing is a safe, fast and virtually painless investigation that identifies whether an allergy is present. It is performed in clinic and the results are available within 15 minutes. It is vital that they 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 sometimes both skin prick allergy testing and IgE specific bloods tests are sometimes carried out. This depends on the specific case history.

What does skin prick testing test for?

Skin Prick Allergy Testing can be used to test for a very wide range of airborne allergens and food substances.  

The following allergens can be tested for: 

  • Inhalant Allergens: House Dust Mite, Grass Pollen, Tree Pollens, Silver Birch Pollen, Ragweed Pollen, Feathers, Animal Dander (cat/dog/horse/rabbit) and Household Mould Spores (alternata & cladosporium).
  • Common Foods: Milk, Egg, Wheat, Soya, Potato, Tomato, Orange, Strawberry, Kiwi and Chocolate (Cocoa).
  • Nuts/Seeds (where appropriate):  Peanuts, Almonds, Walnuts, Hazelnuts, Brazil nuts, Pine nut, Pistachio nut, Pecan nut, Cashew nut, Chestnut, Sesame seed, Sunflower seed.
  • Fish/Shellfish (where appropriate): Cod, Mackerel, Salmon, Tuna, Trout, Hake, Shrimp, Lobster, Crab, Clam, Mussels and Scallops.

Please Note: If you or your doctor would like you to be tested for something not on our list please contact us by e-mail. For example, if you bring a small sliver of fresh food then that 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. PLEASE DO NOT TURN UP WITH A SHOPPING TROLLEY FULL OF THINGS YOU WANT TO BE TESTED FOR (it has happened!).

What does skin prick testing involve?

Skin Prick Allergy Testing

Skin Prick Allergy Testing involves placing a small droplets of allergen onto the skin and then introducing a tiny amount of each allergen into the skin. If allergic sensitivity is present, then a temporary bump called a wheal will form on the skin and the surrounding skin will become red. The results are available within 15 minutes and ready for review by the doctor. It is vital that this result is interpreted there and then by a medical expert. It’s easy to perform an allergy test, the skill lies in interpreting the result in the context of the patient's symptoms as sometimes they are not linked.

Skin Prick Test Result Interpretation

Skin Prick Allergy Test Results

A positive result is measured in millimetres of central wheal and outer flare (redness of skin). There are positive (histamine) and negative (saline) controls to ensure the accuracy of test result.

With inhalant allergens (such as dust mite, pollens, animal hair) the size of the wheal and flare is important but does not always reflect the symptoms. For example a patient will occasionally show a very large wheal and flare (say to dust mites) but not show many symptoms. Equally a relatively small reaction (say to cat hair) in someone only recently exposed to cats is usually very important as within a year of continuous exposure the allergic reaction will probably have increased significantly (as will the patient’s symptoms).

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.

Patch Testing

What is Patch Testing used for?

Patch Testing tests for allergic triggers in a condition called Contact Dermatitis. It does not test for food or inhalent 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