Allergy test

An allergy test is used to look for the trigger when an allergy is suspected. Often, those affected cannot explain which substance causes breathing problems, sneezing or itching. A test can be used to find out which allergen is causing the symptoms.

This information is important for further treatment, because the allergy triggers should be avoided as best as possible to reduce the symptoms . In addition, for many allergies, specific immunotherapy (SIT) is possible and can permanently eliminate symptoms.

There are various methods that, in the case of an allergy, provide fairly clear results as to which harmless substances the immune system is overreacting to:

• prick test: The most common method for detecting an allergy of the immediate type is the prick test. It bears its name because the doctor places small pricks (English: pricks) in the skin, usually on the forearm. Various allergens are dripped onto these spots in a recorded grid. If the immune system reacts to certain substances, redness or wheals form on the affected area after a short time. The larger the wheal, the more clearly a corresponding allergy is present. The results are already visible after about 15 to 20 minutes. The standard prick test includes up to 20 solutions and thus serves to detect a whole range of allergies: e.g. pollen, house dust, animal dander, mold and food.
• Epicutaneous test: Another skin test is the epicutaneous test, which is performed when a contact allergy is suspected. Here, small patches are stuck on the forearm or back, each containing an allergen. Since the contact allergy is a reaction of the late type and the allergic reaction is usually noticeable only after several days, the patches remain on the skin for several days.
• Intracutaneous test: For example, to detect a house dust allergy offers the intracutaneous test. The test is performed on an area of skin on the back by injecting the allergens directly under the skin with a syringe. The result can be read after about 15-20 minutes. This test is usually performed only if other allergy tests have shown unclear reactions.
• Blood test: Many allergies can be diagnosed by a blood test. Here, antibodies (immunoglobulins), such as IgE antibodies against the allergy triggers can be detected. In the case of food allergy IgG antibodies provide clues as to which foods are not tolerated. However, the test is often only performed additionally in case of unclear results.
• Provocation test: In a provocation test, the allergy patient is directly confronted with the allergen, which specifically triggers an allergic reaction . This test is occasionally used for food allergies. In the case of hay fever, after inhaling the allergens, the doctor measures whether the lung function changes due to a reaction of the airways. A provocation test should always be done under medical supervision, as it carries certain risks. In addition, it should not be performed if the patient develops severe symptoms or suffers severely from shortness of breath during an allergic reaction.

Both allergy tests provide results on different allergies. However, the prick test is often preferred because it can be performed quickly and on an outpatient basis and provides an initial diagnosis after only 15 to 20 minutes. Blood testing, on the other hand, usually takes several days, but is the more convenient method for many patients. Often, in the case of inconclusive test results, the blood test is performed in addition to a skin test in order to confirm the results.

If hay fever or allergic asthma are suspected, the ENT doctor is usually the first place to go for an allergy test. For skin rash due to a possible contact allergy the dermatologist will do the test. To clarify a possible food allergy, the gastroenterologist will help. He can also rule out other gastrointestinal diseases as the cause of the symptoms.

Since an allergy test deliberately induces an allergic reaction, it also involves certain risks. Although the concentration of the allergens administered is very low, circulatory problems, shortness of breath or even anaphylactic shock are possible. For this reason, you should not perform a test alone at home, but always under medical supervision. In an emergency, the doctor can administer medication immediately.