Treatments & Therapies

Skin prick test – treatment, effect and risks

Prick-Test

The skin prick test is an internationally recognized standard method for detecting type 1 allergies (immediate reaction) such as pollen or food allergies . As a rule, a skin prick test is associated with only minor risks and side effects.

What is the prick test?

The prick test is an allergological examination method that, analogous to the scratch test (scratch test), can be used to identify the allergens (allergy-triggering substances) that trigger a type 1 allergy (antibody-mediated allergic reaction of the immediate type).

Food allergies, allergic asthma or hay fever are characteristic allergies that can be detected in a skin prick test. For this purpose, different allergen-containing test solutions are applied to marked areas of skin on the forearm or upper back and the skin is pricked superficially with a prick lancet or prick needle. Based on the reactions, the triggering allergen and the severity of the specific allergy can be determined.

Function, effect & goals

skin prick test is usually used to detect or rule out sensitization to certain allergy-causing substances (allergens).

The skin prick test is particularly suitable for detecting type 1 allergies. Type 1 allergies are characterized by the fact that the allergic reaction that occurs immediately (a few seconds to minutes) is mediated by IgE antibodies (immunoglobulin E). Upon contact with the allergen, the organism forms IgE antibodies, which bind to the mastocytes (mast cells) of the immune system and cause the release of inflammatory mediators (inflammatory messengers) such as histamine and leukotrienes. These cause acute inflammatory reactions (including hay fever, allergic asthma, urticaria and hives ).

A standard test usually includes around 15 to 20 test solutions with the most common allergens, whereby these can be individually adapted or expanded (including special foods, types of pollen, insect venoms) depending on the specific question. The allergens to be tested are dropped onto areas of skin marked with a pen on the inner forearm or upper back. The skin is then pricked superficially and without bleeding with a prick needle or prick lancet so that the allergens to be tested can penetrate the epidermis .

If an allergy is present, the release of histamine causes the fine blood vessels to dilate and cause reddening . The blood vessels also become more permeable, so that interstitial fluid (tissue fluid) can escape and the skin swells ( wheal formation ). The additional nerve irritation can also cause pruritus ( itching ). The evaluation or assessment of the test result is usually carried out after about 15 to 20 minutes and is compared with a positive (0.1 percent histamine solution) and a negative control with saline solution for a better assessment.

In the case of the negative control with sodium chloride, wheal formation should not occur, while this should occur in the case of the positive control due to the applied histamine. The extent of the allergy can be determined based on the diameter of the redness and wheals present and the corresponding symptoms.

Finally, the results are recorded in a test protocol or allergy pass. A specific form of the prick test is the so-called prick-to-prick test, in which the prick lancet is first pricked into the test solution and only then into the marked area of ​​skin.

Risks & side effects

As a rule, a prick test correlates with minor side effects and risks, although pronounced local reactions can be caused in rare cases.

In very rare cases, generalized pruritus, shortness of breath and/or anaphylactic shock (circulatory collapse) can be observed. The risk of more pronounced reactions is particularly increased when non-standardised allergen solutions (including substances brought by the person concerned), to which there is a strong sensitization, are tested as part of the skin prick test. In addition, the evaluation of a skin prick test can prove to be difficult in some cases. The existing skin reaction does not always have to reflect the severity of the sensitization or allergy.

Despite a stronger sensitization, in some cases only a weak reaction can be triggered and vice versa. In particular, solutions applied with pollen and/or food allergens can contain substances that also have botanically related species, so that although a reaction can be observed, the underlying allergen has not been identified.

In addition, certain medications such as antihistamines , corticosteroids , sleeping pills and tranquilizers , and immunosuppressants (medicines that suppress the immune system) can affect the result of the skin prick test and should be discontinued beforehand if necessary. In the run-up to the prick test, irritation, inflammation and damage in the test area must also be ruled out, as these can lead to an increased reaction and correspondingly to false positive results.

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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.