Allergy test: how does it work?

What happens before an allergy test?

An allergy test usually begins with a conversation with the doctor treating you. During this first interview, the so-called anamnesis, he will ask you a series of questions. This is the only way he can interpret your symptoms more precisely and determine whether your symptoms are really an allergic reaction and whether other diseases can be ruled out. So that you don’t have to think long and hard, you should prepare yourself for the following questions:

• What symptoms have you observed?
• How long have the symptoms been present?
• When exactly do the symptoms appear?
• Are allergies known in your family?

Allergy tests at a glance

Below we have put together an overview of the most common allergy tests:

• In the rub test , the doctor applies various allergy-triggering substances to the skin of your forearm using a gauze swab. On the forearm side of your other arm, he also applies a saline solution that does not cause any skin reactions. After about 15 to 20 minutes, he compares the skin reaction with the area to which he applied the allergy-causing substances. However, this test is only useful for type I allergies, i.e. if the allergic reaction occurs within a few minutes, such as with hay fever or an allergy to insect venom .
• The skin prick test , also known as the “stick test”, is considered the standard allergy test because its result is very precise. The doctor applies test solutions to your forearm or back and pricks the skin under the solution with a so-called prick needle. At the same time, for comparison, he applies a saline solution, which does not cause a skin reaction, and a histamine solution, which usually always causes a skin reaction, to adjacent skin areas. After just 15 to 20 minutes, the doctor can determine whether you are allergic to certain substances. Similar to the rub test, this allergy test can only be used to detect type I allergies.
• The intradermal test is considered to be the riskiest allergy test because it can trigger strong allergic reactions. The doctor injects an allergy-causing substance under your skin, which is supposed to trigger a reaction. He also does this with a saline solution and a histamine solution in order to take a closer look at the different reactions. With this test, too, a reaction can already be seen after 15 to 20 minutes.
• In the epicutaneous test , also known as a patch test or plaster test, the doctor applies the allergy-triggering substances to the skin of your back or upper arm with plasters. The patches stay on the skin for 48 hours, after which the doctor can determine which substances you are allergic to. In addition to type I and type II allergies, this allergy test can also be used to detect type IV, so-called late types.
  Note: With this allergy test, the skin must not come into contact with moisture or UV radiation. During the 48 hours you should therefore refrain from bathing and showering, sports, sunbathing or visits to the solarium.
• In the provocation test, you are exposed directly to the allergen. For example, if you are allergic to certain medications, you must take the corresponding active ingredient. Since a provocation test could result in anaphylactic shock , it is rarely carried out. In addition, a doctor must always be present during this allergy test.
• For a blood test , the doctor will take a small amount of your blood and send it to the laboratory for examination. He then evaluates the results.