Allergy test can be really beneficial in children with allergic manifestations. Skin prick test is a type of allergy test in which sensitization to different allergens can be demonstrated on the skin. This helps in identifying culprit allergens so that avoidance measures can be implemented. Knowledge of allergen sensitization and its correlation with clinical history of allergies can help your physician guide specific pharmacotherapy and advice allergen immunotherapy as well.

How is skin prick test done?
Skin prick test is performed by an allergy specialist in the clinic. It is not a lab test. Allergen extracts are applied as small drops on the arm and its pricked using a lancet. The allergen percolates in the superficial layer of the skin. Normal saline and histamine are also applied as negative and positive controls of the test. After 15 minutes, the test is read. In case of sensitization to allergen, a swelling or wheal is seen at the site of the prick. The swelling is then measured and interpreted by an allergy specialist.
It is important to understand that a positive test does not always imply that the child’s reactions are due to that allergen, the clinical history of exposure must be elicited.

When do you need a Skin prick test?

Your allergy specialist may advise skin prick test if your child is suffering from the following conditions:

• Respiratory allergies – Allergic rhinitis, asthma
• Allergic conjunctivitis or vernal keratoconjunctivitis
• Atopic dermatitis
• Urticaria and angioedema

Skin prick test helps us identify the allergen which can help us in

• Implementing allergen avoidance measures
• Advice duration and timing of pharmacotherapy (in case of seasonal allergens)
• Advice allergen immunotherapy
• 
  

How should I prepare for a skin prick test?
Skin Prick test is performed in the clinic and takes around 15-20 minutes. Your doctor will advise you to avoid any oral medications for a week prior to the test. Inhalers and nasal sprays can be used before undergoing the test. The test is done on the arm in most cases so make sure that you wear comfortable clothing and your sleeves can be rolled up easily. In children with atopic dermatitis, test is usually deferred in the presence of active lesions on the arm.

What kind of allergens are tested in the skin prick test?
Different air-borne allergens and food allergen extracts are available and can be used to test for sensitization. Aeroallergen mainly include different common pollens, weeds, grasses, insects, dust mites and storage mites, fungi and animal dander. A variety of food allergen extracts are also available. The allergen to be tested in an individual are selected by the allergy specialist based on the clinical history and symptoms.

Is skin prick test painful?
Skin prick test involves a very superficial scratch on the skin with a lancet. Some children describe it as a mosquito bite and some say they didn’t feel a thing. In most cases, it is practically painless.

At what age can this test be performed?
Skin prick test can be done in children of all age groups including infants. However, reliability of the test is maximum in children >3 years of age. Indications of performing the test in children less than 3 years are very few and specific. For example, children with acute allergic reaction to any food item, anaphylaxis, suspected food allergies, in infants with wheeze to assess the risk of asthma.

Is skin prick test safe?
Skin prick test is an absolutely safe procedure with minimal local reactions like itching and redness on the arm. In some children, there may be appearance of swelling at the prick site few hours after the test. This does not hold any value in interpretation of test result. There is a small theoretical risk of severe allergic reaction to the allergen.