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  • Dr. Sunena Saju

All you need to know about Allergy

Updated: Nov 13, 2021

What is an allergic reaction?


Your body’s immune system works by identifying harmful substances such as germs, or poisons, and produces antibodies: specialist proteins that help white blood cells to ‘fight’ the harmful substance. However, sometimes your body can mistakenly identify a harmless substance, such as pollen, as a threat. It produces antibodies to try to fight off the threat, and it is these antibodies that produce side effects. Depending on the allergen, the side effects will differ. If the body is releasing the antibody histamine, side effects will include sneezing, swollen eyes, and a runny nose. For skin allergies, symptoms include redness and dryness, or a rash.


Causes of allergic reaction?


Although it is possible to have an allergic reaction to almost any substance, there are a few common allergies that many people suffer from. Dust mites are a big cause of the allergic reactions. Dust mites live in house dust, often in bedding or soft furnishings, and it is their waste that the body reacts to. For this reason, it is advised to change pillows and bedding regularly to prevent build-up of this allergen. Pollen is another very common allergen, so common in fact that we see pollen count recorded in many weather reports. As the temperatures rise, more pollen is found in the air, especially in less urban areas. Tree pollen is especially problematic as it is high in the air, meaning that as it falls it irritates those who are susceptible to it. Less common causes of allergic reaction include some prescription drugs or painkillers. Some people are allergic to antibiotics and do not find out until they take the medication.

Symptoms of allergic reaction differ hugely. Some people only ever experience very mild symptoms – for example, sneezing when the pollen count is very high. Anaphylactic shock is the most severe reaction to an allergy and is rapid in onset. If untreated it can cause death, so it is very important that those with allergic reactions seek medical guidance in case they are in danger of reacting this severely

How to test for allergies?


Skin prick test


Skin prick testing is the most common allergy test performed in an allergy clinic by specially trained staff. It is a simple, safe and quick test, providing results within 15-20 minutes. This will enable you to receive a diagnosis and management plan at your appointment. The skin prick test introduces a tiny amount of allergen into the skin, eliciting a small, localized allergic response, in the form of a wheal (bump) and flare (redness) at the site of testing.

The patient needs to avoid taking anti-histamines and certain other medications before the test. Long-acting antihistamines (those that do not cause drowsiness) should be stopped for five days; short-acting antihistamines can be stopped 48 hours beforehand. Many cough mixtures contain an antihistamine; therefore please tell your consultant who is performing the test, any medication that you have taken.

Intradermal testing (ID)


Intradermal tests are used to investigate allergies to some medications e.g. penicillin and venoms of bee and wasp. The test involves a small injection of often diluted medications or venoms into the dermis of your skin. ID is carried out on the inner forearm The skin is coded with a marker pen to identify the medications/venoms to be tested. A drop amount of the medication/venom is injected into the skin. The results are ready within 15-20 minutes

Blood test


Blood tests measure the amount of Immunoglobulin E (IGE) antibody circulating in the blood. The test is carried out on a small sample of blood, usually taken from a vein in the arm in the usual way. The sample is then sent to a laboratory and the results are available in 7 to 14 days. These tests are particularly useful when skin prick testing is impractical, for example, when the patient has extensive eczema.


Managing Your Allergy Involves Two Steps:


1. Reducing the risk of an allergic reaction by avoiding the allergen, wherever possible.

Avoiding allergens requires identifying the cause of your allergy and then taking steps to reduce your exposure to the allergen. Hopefully, avoidance techniques can improve symptoms, but medicines are often needed (especially with eczema, atopic asthma and hay fever) to provide symptom control. Nonetheless, in almost all cases, a combination of these two approaches will result in significant improvement in allergic symptoms.

2. Medical treatments to reduce symptoms including: medications and immunotherapy.


  1. Medication:

  • Antihistamine Most people with mild allergies find that taking antihistamine tablets when exposed to allergens will help. These can be taken on a daily basis and help to reduce the symptoms of allergens, such as sneezing, a runny nose and red, swollen eyes.

  • Steroids For more serious allergies, steroids are sometimes prescribed to tackle the symptoms

  • Emollient creams are generally used for skin conditions. In simple terms, they are creams that contain water and oil to keep the skin protected from allergens and lubricated to lessen the symptoms of eczema. They also keep the skin clean and free from breakages caused by scratching, which then open up the skin to the possibility of infection.

  • Adrenaline The use of adrenaline (epinephrine) as an emergency allergy treatment is well understood by doctors, and it has saved many lives

  • Cromoglicate works by blocking the responses of the cells that release the histamine during an allergic reaction and can be a useful alternative to an anti-histamine in preventing allergic reactions.

2. Immunotherapy: is a type of treatment for allergies that works by suppressing a

specific immune response. It is a way of changing the body’s immune system to help it to recognize harmless substances and learn not to respond negatively to them. This is known more specifically as suppression immunotherapy and is the only available treatment for allergies that deals with the allergy itself rather than treating the symptoms, such as antihistamines or steroids. Immunotherapy works by exposing the body to the allergen a minuscule amount at a time, allowing the body to slowly adjust and become less sensitive to it. This process is known as desensitization. The treatment is administered by a course of injections, tablets or drops under the tongue over a period of one to three years by a doctor


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