The allergy test is a type of examination indicated to identify whether the person has any type of skin, respiratory, food or drug allergy, for example, and thus indicate the most appropriate treatment according to the frequency and intensity of symptoms. .
Allergy testing is normally recommended by a dermatologist or allergist when a person has itching, swelling or redness on the skin, and can be done by applying the potentially allergenic substance to the forearm or back, or by eating a certain food, if necessary. food allergy is being investigated.
This exam is carried out in the doctor’s office and it is recommended to avoid the use of creams before the exam and the use of antihistamine medications, as these may interfere with the exam results.
How is done
The allergy test may vary according to the signs and symptoms presented by the person and the type of allergy to be investigated, and may be recommended by the doctor:
1. Forearm Allergy Test
The forearm allergy test, also called the Prick test, is done by applying a few drops of substances known to cause allergies to the forearm. In some cases, in addition to applying the substance to the skin, a few pricks may also be made with a needle.
After application, you must wait 20 minutes to check if there is a reaction. The reaction is said to be positive when the presence of a red ball in the area is verified, which can cause swelling and intense itching in the area. Understand how the forearm allergy test is performed.
2. Back allergy test
The back allergy test, also known as a contact allergy test, consists of sticking an adhesive tape on the patient’s back with a small amount of the substance thought to cause an allergy. Then, you must wait up to 48 hours and observe whether any reaction appears on the skin.
3. Oral provocation test
The oral provocation test is carried out with the aim of identifying food allergies and consists of ingesting a small amount of the food possibly causing the allergy and then observing the development of a reaction.
4. Blood test
The doctor may also prescribe blood tests to identify changes suggestive of allergies. One of these tests is known as the RAST test, in which the levels of IgE antibodies produced against various substances are measured. Understand better what the RAST test is and what it is for.
How to prepare for the test
To take the allergy test, it is recommended that the person suspend the use of some medications that may interfere with the result, mainly antihistamines, because the use of this medication may prevent the body’s reaction to the substance being tested, making it impossible to do so. identify the allergy.
It is also recommended to avoid applying creams, especially when skin allergy testing is indicated, as this may also result in interference with the result.
In addition to these guidelines, the patient must comply with all the specific instructions indicated by the doctor, so that the allergy test correctly informs the cause of the allergy.
Make an appointment with your nearest doctor to receive all instructions for the exam:
When is indicated
The allergy test is recommended by the doctor mainly when the person presents signs and symptoms of allergy, such as:
- Itch;
- Swelling;
- Redness of the skin;
- Swelling in the mouth or eyes;
- Frequent sneezing;
- Runny nose;
- Gastrointestinal changes, such as diarrhea.
Thus, according to the symptoms presented by the person, the doctor can recommend the most appropriate test to investigate the cause of the symptoms, which could be the use of some medications, a reaction to a product or fabric, mites or dust, latex, mosquito bites. or animal hair, for example. Furthermore, another common cause of allergy that should be investigated by allergy tests is food, especially milk and dairy products, eggs and peanuts. Find out more about food allergies.
Bibliography
- DAHER, Sylvia; GALVE, Clovis; ABE, Augustus; COCCO, Renata. Diagnosis in IgE-Mediated Allergic Diseases. Rev. bras. allergy. immunopathol. Vol 32. 1 ed;
- Brazilian Society of Allergy and Immunopathology. Allergy skin tests. 2018. Available at: <http://www.ans.gov.br/images/stories/Particitacao_da_sociedade/2017_gt_cosaude/gt_cosaude_reuniao_4_presentacoes.pdf>.
