Skin allergy tests

Alternative names

Contact tests. Skin allergy test.

Definition

Set of diagnostic tests that consists of identifying the presence of a certain hypersensitivity (allergy) to a certain substance or compound through the use of allergens applied to or under the skin. Allergens are substances capable of triggering an immune-type response (skin rash, lacrimation, runny nose, asthma, etc.) in people who are especially sensitive to them. The most commonly used allergens are food, pollen or dust particles, antibiotics, metals, animal hair, poisons, chemicals, and so on. allergy skin tests measure the type and size of reaction (rash) caused by the allergen when it comes into contact with the skin. There are different types of skin tests, the most commonly used are:

• Pick test: a drop of allergen is applied to the skin
• Intradermal test: a small amount of allergen is inoculated into the skin.
• Patch: different allergens in the form of adhesive patches are applied to the skin of the back for 48 hours.

How is the study done?

The study is carried out on an outpatient basis in the Allergology or Immunology Units of the medical center or hospital by qualified personnel. The patient must bare the area of ​​skin under study, generally the arm, forearm or back. The explorer inoculates or applies a small amount of one or more allergens, after a minimum time of 20 minutes it will be assessed if there is reactivity to the allergen and its intensity, checking if there is any type of reaction at the skin level (itching, rash, wheal, etc. ). The study usually lasts 30 minutes.

Preparation for the study

The study does not require prior preparation by the patient except for the correct cleaning of the skin area to be studied. The use of creams and irritating substances should be avoided the days before the study and especially the day of the study. Some drugs can interfere with the study so their use should be avoided in the days prior to the study.

What does it feel like during and after the study?

The study is not painful for the patient. A slight discomfort may be felt when applying or inoculating the allergen. If a skin response to the allergen occurs, the patient may experience itching, stinging or burning in the area. The discomfort will disappear in the following minutes or hours. An antihistamine may be given to minimize the reaction at the end of the study.

Study risks

• Skin rash, wheal.
• asthmatic attack (rare)
• Severe anaphylactic reaction (exceptional given the small amount of allergen used during the study).

Study contraindications

The patient should consult with his doctor before carrying out the study in case of:

• Pregnancy and breastfeeding.
• Taking medication, especially antihistamines or corticosteroids.

Reasons why the study is carried out

Skin allergy tests are widely known and used diagnostic tests in the field of Medicine as they provide objective information on allergic-type processes. They are used to confirm or rule out whether symptoms such as skin rash, lacrimation, rhinitis, asthma, etc., are allergic or not. They allow to identify the type of allergen for which the patient is allergic.

Family and Community Medicine Specialist