Allergy testing to identify allergens

Allergy testing to identify allergens

It can be difficult to identify the specific allergen responsible for an allergic reaction through everyday observation alone, as most foods, substances, and even the air we breathe contain a combination of different components.

Allergy tests help identify the specific substances that trigger an allergic reaction. An allergist selects the most appropriate test for each patient individually. Testing methods may include a skin-prick test, scratch test, intradermal test, patch test, photopatch test, or blood tests.

How quickly are allergy test results available?

In most cases, the results of allergy tests are visible within 15–20 minutes of the test being performed.

Results from blood tests used to identify allergens are usually available within one to several days, depending on the laboratory’s workload.

Patch testing for specific contact allergens

Patch testing for contact allergens is completely painless and does not damage the patient’s skin.

A dermatologist selects a panel of specific allergens, known as haptens. These chemical substances are placed in small aluminium chambers and attached to the skin on the patient’s back using a special adhesive patch.

The patches are removed after two days, and the results are assessed. An additional appointment with the dermatologist may be recommended after 2, 5, or 7 days to rule out a delayed allergic contact dermatitis reaction.

The most commonly identified contact allergens include:

  • nickel;

  • medications;

  • balsam of Peru;

  • formaldehyde;

  • latex;

  • various plant extracts;

  • nail polish, hair dyes, and hair-styling products.

Contact-allergen testing may be recommended for patients with:

  • suspected allergic contact dermatitis;

  • other skin conditions that increase sensitivity to contact allergens, including atopic dermatitis, eczema, contact dermatitis, or dyshidrosis;

  • chronic eczema with no identified trigger;

  • suspected medication intolerance or a previous anaphylactic or allergic skin reaction to medication.

Patch testing for specific contact allergens is not performed:

  • if there is an active inflammatory process on the skin of the back;

  • if the patient has used antihistamines or hormonal corticosteroid medication during the four days before testing;

  • if the patient has sunbathed during the 7–10 days before testing;

  • during pregnancy or breastfeeding.

Measurement of allergen-specific IgE antibodies in the blood

This blood test measures antibodies associated with specific allergic reactions. Measuring allergen-specific IgE antibodies helps identify the group of substances responsible for triggering the allergy.

A blood sample is taken from a vein for analysis.