Prick test: what it is, what it is for and how it is done

The Prick test is a quick allergy test that allows you to identify which types of substances a person is most sensitive to.

To carry out the Prick test, substances that can cause allergies are placed on the forearm and, after 15 to 20 minutes, it is observed whether any skin reaction has occurred.

Despite being quite sensitive and can be carried out on people of all ages, the result of the Prick test is more reliable from the age of 5, as at that age the immune system is already more developed.

What is it for

The Prick test is indicated to check whether the person has any type of food or respiratory allergy.

The main allergies tested are:

• Shrimp;
• Leite;
• Ovo;
• Peanut;
• Mites:
• Dust;
• Insect bites;
• Latex.

Most of the time, the Prick test is carried out together with the test for contact allergies, in which an adhesive tape containing some potentially allergenic substances is placed on the person’s back, only being removed after 48 hours. Understand how the contact allergy test is performed.

How the test is done

The Prick test is quick, simple, safe and causes no pain. In order for this test to be carried out, it is recommended that the person suspend the use of anti-allergy medications, in the form of tablets, creams or ointments, for approximately 1 week before carrying out the test, so that there is no interference with the result.

Before starting the test, it is important that the forearm is observed in order to identify any signs of dermatitis or lesions, as if these changes are noticed, it may be necessary to carry out the test on the other forearm or postpone the test. The test is done following the following step by step:

1. Forearm hygienewhich is the place where the test is carried out, using 70% alcohol;
2. Application of one drop of each substance potentially allergenic with a minimum distance of 2 centimeters between each one;
3. Carrying out a small drilling through the droplet with the aim of bringing the substance into direct contact with the body, leading to an immunological reaction. Each piercing is done with a different needle so that there is no contamination and interferes with the final result;
4. Observation of the reactionand it is recommended that the person remains in the environment in which the test was carried out.

The final results are obtained after 15 to 20 minutes and it is possible that during the wait the person will notice the formation of small elevations on the skin, redness and itching, indicating that there has been an allergic reaction. Although itching can be quite uncomfortable, it is important that the person does not scratch.

How to understand the results

The results are interpreted by the doctor by observing signs on the skin, such as redness or elevations in the area where the test was performed. The tests are considered positive when the red elevation on the skin is 3 mm or greater in diameter.

It is important that the results of the Prick test are evaluated by the doctor taking into account the person’s clinical history and the results of other allergy tests.