Allergic reactions are very common. In developed world, 20% people suffer from nose allergy, 6% suffers from food allergy and 20% from some sort of skin allergy.
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What is Allergy?
Allergy is a condition in which our immune system gets very sensitive to harmless things/chemicals present in the environment resulting in symptoms like red eyes, runny nose, sneezing, itching and breathing difficulty.
What things can cause Allergy?
Common air allergens
| Cat hair | House dust mite |
| Dog hair | Mold |
| Horse hair | Grass pollens |
| Rabbit | Tree pollens |
| Animal Feathers | Flowers |
Common food allergens
| Nuts | Seafood | Dairy | Fruits | Vegetables | Meat | Cereal |
| Walnut | Salmon | Milk | Orange | Tomato | Beef | Wheat |
| Peanut | Cod | Cheese | Apple | Potato | Chicken | Rye |
| Cashew | Shrimp | Egg | Strawberry | Soyabean | Lamb | |
| Pistachio | Crab |
Common skin allergens
| Jewelry | Leather | Shoes | Glue |
| Perfumes | Hair dyes | Gloves | Topical medicines |
| Cement | Sticky plaster | Cosmetics |
How can we test allergy?
Skin Prick test (SPT) is the most used test for allergy diagnosis. It is quick and results are visible.
| Indications | Allergic rhinitis (Nose allergy) Suspected food allergy Refractory Asthma (asthma not responding to usual treatment) Suspected food or drug allergy |
| Contraindications | Severe red and itchy skin (dermatitis) Severe redness and swelling of skin on pressure or trauma (dermatographism) History of severe allergy (anaphylaxis) Age below 2 years Uncontrolled Asthma |
How is Skin Prick test performed?
SPT is usually performed on skin of forearm or back. Skin is cleaned with a sterile alcohol swab, then a drop of suspected allergen is applied on the marked area of the skin in a grid pattern. Then a small prick with a sterile needle is done through the drop to allow allergen to penetrate the skin. Allergy is indicated when a small insect bite size lump appears over the site within 15-20 minutes. Risk of severe reaction is very low because a very small amount of allergen goes into the superficial layer of skin.
How are results interpreted?
Results are assessed size of lump or wheal on prick site.
| Wheal diameter 5-10mm | Mild allergy |
| Wheal diameter 10-15mm | Moderate allergy |
| Wheal size >15mm | Severe allergy |
What are symptoms of food allergies?
It can be divided into two groups.
- Immune/allergic reaction
- Non-immune (food intolerance)
What are Immune mediated food allergies?
- These food allergies are caused by IgE antibodies or non-IgE antibodies.
- Immediate symptoms of allergy appear from IgE antibodies.
- Skin prick test is good for IgE mediated reactions.
Delayed symptoms of allergy (>2 hours) appear from non-IgE antibodies. Skin prick test may not give definitive results though patient may still suffer from food allergies. You may consider ALCAT test (Antigen Leukocyte Cellular Antibody test).
What is treatment of food allergies?
Avoid the triggering food. Maintain a food diary.
What is immunotherapy?
Immunotherapy is a treatment in which body is exposed to known allergens in a controlled way to reduce severity of allergic reactions. It is given in form of injections or sublingual drops from accredited labs.
Who can get immunotherapy?
People suffering from allergic rhinitis, allergic asthma, allergic conjunctivitis, insect sting allergy.
Who cannot get immunotherapy?
People who have food allergies, hives or urticaria and eczema cannot receive this treatment.
