Allergy Test, Here's What You Should Know

Table of contents:

Allergy Test, Here's What You Should Know
Allergy Test, Here's What You Should Know

Allergy test is a procedure to find out if the patient has an allergic reaction to certain substances or objects. Allergy testing can be done in the form of blood tests, skin tests, or with an elimination diet

Allergies occur when the immune system overreacts to substances or objects that are actually harmless. These reactions can range from mild symptoms, such as sneezing, runny nose, or nasal congestion, to severe, life-threatening symptoms, namely anaphylaxis.

Allergy Test, Here's What You Should Know - Alodokter

Types of Allergy Causing Substances (Allergens)

There are three types of allergens that commonly cause allergies, namely:

  • Inhaled allergenInhaled allergen is a type of allergen that triggers an allergic reaction when it enters the nose, throat or lungs. These types of allergens include dust, pollen, and animal dander.

  • Contact allergenThis type of allergen triggers an allergic reaction in the body when it interacts with the skin. Some examples of contact allergens are nickel, fragrance in soap or perfume, and chemicals, such as latex.

  • Gastrointestinal allergens Gastrointestinal allergens are allergens that trigger allergic reactions when they enter the digestive system. These allergens are commonly found in foods, such as nuts, seafood, and soy. Certain medications, such as penicillin antibiotics and sulfonamides, are also gastrointestinal allergens.

Allergy Test Indication

The doctor will suggest allergy testing for people who experience the following symptoms:

  • Sneezing
  • Runny nose or stuffy nose
  • watery and itchy eyes
  • Vomiting
  • Cough
  • Diarrhea
  • Shortness of breath
  • Wheezing or wheezing

However, these symptoms also need to be accompanied by suspicion of certain allergens and a family history of allergies, asthma, and eczema

Contraindications for Allergy Test

Blood tests, skin patch tests, and elimination diets are relatively safe for anyone. However, the skin prick test is not recommended for children under 1 year of age, pregnant women, and people with the following conditions:

  • Have had a severe allergic reaction (anaphylaxis)
  • Suffering from uncontrolled asthma
  • Suffers from eczema and psoriasis which cover most areas of the skin on the hands and back

Patients with the above conditions may be advised to undergo allergy testing by other means, generally through a blood test.

Allergy Test Alert

There are several things that must be considered before undergoing an allergy test, namely:

Skin test

  • Allergy testing through the skin should only be done under the supervision of a doctor, because there is a risk of anaphylactic shock during the test.
  • Patients who have recently experienced an anaphylactic reaction to an unknown allergen may undergo skin allergy testing for diagnostic purposes. However, it is recommended that the test be performed 4–6 weeks after the anaphylactic reaction occurs.
  • Some medications need to be discontinued at least 2 days before the skin allergy test. Therefore, inform all medications and supplements that are being used when consulting with your doctor.
  • The doctor may advise the patient not to undergo the skin test and replace it with another test if stopping certain medications would be more risky for the patient.

Blood test

  • Blood allergy test is less accurate than skin allergy test. In addition, the results of allergy tests through blood also take longer to come out than allergy tests through skin.

Elimination diet

  • The elimination diet can reduce a person's nutritional intake, so its implementation must be supervised by a doctor or nutritionist, especially if it is carried out on children and pregnant or nursing mothers.

Before Allergy Test

Before planning an allergy test, the doctor will ask the patient's and family's medical history, lifestyle and daily activities, as well as when and why these complaints appear.

In addition, the doctor will also ask what drugs the patient is currently taking. Your doctor may recommend stopping certain medications that could affect test results or risk delaying the procedure you need to undergo. These drugs include:

  • Antibody blocking drugs, such as omalizumab, which are commonly used in patients with severe asthma
  • antihistamines, such as cetirizine
  • Beta-blocking drugs, such as atenolol
  • Corticosteroid drugs, such as dexamethasone, both in the form of oral drugs and ointments
  • ulcer drugs, such as cimetidine and ranitidine
  • Tricyclic antidepressant drugs, such as amitriptyline
  • benzodiazepine drugs, such as diazepam

If necessary, the doctor will also perform a physical examination, to find out whether the patient's complaints are caused by other diseases.

Types and Procedures of Allergy Tests

There are several types of allergy tests that are commonly performed to determine allergens, namely:

Skin prick test

Skin prick test is the most common type of allergy test. The following are the stages of allergy testing through a skin prick:

  • The doctor will mark the skin based on the type of allergen to be instilled.
  • The doctor will drip a solution that has been mixed with the allergen onto the patient's skin. At this stage, there are 10–12 allergens that may be instilled based on suspicion of allergy.
  • The doctor will pierce the area of ​​​​the skin that has been dripped with the solution with a very thin needle, so that allergens can enter under the surface of the skin.
  • The doctor will watch for signs of allergies that may appear on the skin. If present, an allergic reaction will generally appear within 15-20 minutes.

Intradermal skin test

Intradermal skin test or intradermal skin test is usually done if there is a suspicion of allergy to bee stings or certain antibiotics. This test may also be recommended if the patient's skin prick test is negative, but the doctor still suspects that the patient is allergic to an allergen.

In an intradermal skin test, the doctor will inject a small amount of the allergen just under the skin of the patient's arm. After that, the doctor will monitor for 15 minutes to see if there is an allergic reaction in the injection site.

Paste test

Patch testing or patch testing is generally done to detect allergens that cause contact dermatitis. The allergen can be metal, plastic, rubber, or skin cream. The following are the stages of the patch testing procedure:

  • The doctor will attach a number of patches or adhesives to the patient's back. Each patch has been assigned a specific type of allergen that is suspected of causing an allergic reaction in the patient.
  • This adhesive must be used for 2 days. During these 2 days, the patient is not allowed to take a bath or do activities that can cause excessive sweating.
  • After two days, the patient must return to the doctor. The doctor will remove the adhesive and check for irritation on the patient's back which indicates an allergic reaction.

Allergy test through blood

The procedure for blood allergy testing generally takes less than 5 minutes. Allergy testing through blood is done by first taking a sample of the patient's blood. The blood sample will then be taken to the laboratory so that the patient's immunoglobulin E levels can be checked.

Immunoglobulin E (IgE) is an antibody produced by the immune system to fight substances that are considered a threat. When the body experiences an allergic reaction, the amount of IgE will increase.

The IgE measured can be the total number of IgE antibodies in the body (total IgE test) or the number of IgE antibodies that appear in response to an allergen (specific IgE test).

Elimination diet

The elimination diet is used to detect food allergies. This type of allergy test can be done independently by the patient at home, but it is better to stick with the doctor's advice and supervision.

The elimination diet procedure takes 5–6 weeks, which is divided into two phases, namely:

  • Elimination phase

    This phase is done by avoiding the consumption of foods suspected of triggering allergy symptoms, it can be one type of food or more than one type at a time. Some types of foods that often trigger allergies are peanuts, corn, soy, milk, eggs, wheat, and seafood.In the elimination phase, patients can pay attention to whether their symptoms improve or not when the suspected food is stopped. Generally, this phase lasts for 2-3 weeks. If the symptoms do not go away, the patient needs to report it to the doctor.

  • Reintroduction phase

    If during the elimination phase the allergy symptoms disappear, the reintroduction phase can be started. Food reintroduction should be done per each type of food, each within 3 days. During these 3 days, patients need to pay attention to the presence or absence of allergy symptoms that appear, such as rash, shortness of breath, or flatulence.

After Allergy Test

Allergy test results through the skin can be known in minutes, except for patch tests. Meanwhile, for allergy testing through blood, it takes several days to wait for the results of the analysis in the laboratory. The following is an explanation of the allergy test results:

Allergy test results through skin

The results of allergy testing through the skin, namely skin prick test, intradermal skin test, and patch test, are positive if the area of ​​the skin being tested becomes red, itchy, and appears as a pale-colored bump that increases in size during the test.

If the skin condition remains normal, it means that the patient is not allergic to the allergen used in the test.

Allergy test results via blood

Test results that show the total IgE in the body is higher than the normal limit can indicate that the patient has allergies. However, the total IgE test cannot identify the type of allergen causing the allergy. To find out the type of allergen, the patient must undergo a specific IgE test.

Result of elimination diet

If the patient does not experience an allergic reaction during the reintroduction phase, the food is safe for consumption. On the other hand, if an allergic reaction occurs, the cause of the allergy has been identified, so the patient must avoid these foods in their daily diet.

Side Effects and Complications of Allergy Tests

Allergy testing through blood can be said to not cause serious side effects, except for pain, bruising, or light bleeding at the injection site.

If done according to the procedure, the elimination diet test also has a small risk of causing side effects. However, vulnerable groups, such as children and pregnant women, may experience malnutrition during the elimination phase.

For the skin allergy test, some side effects that may appear after undergoing the test are:

  • itching
  • Skin redness and irritation
  • Swelling in the examination area
  • Itchy bumps appear on the skin

In some cases, skin allergy testing and the reintroduction phase of the elimination diet can cause an anaphylactic reaction. These conditions include medical emergencies that can be life-threatening for the patient. An anaphylactic reaction can be recognized by the following signs and symptoms:

  • Dizzy
  • Nausea, vomiting, or diarrhea
  • Heart rate is weak and fast
  • Reaction on the skin which includes itching and redness
  • Difficulty breathing due to narrowing of the airways and swelling of the throat or tongue

If an anaphylactic reaction occurs while not in the hospital, immediately contact a doctor or visit the nearest emergency room so that treatment can be given as soon as possible.

Popular topic