The big itch

An allergy is the response of the body’s immune system to normally harmless substances, such as pollens, foods, and house dust mites. Whilst in most people these substances (allergens) pose no problem, in allergic individuals their immune system identifies them as a ‘threat’ and produces an inappropriate response. This can be relatively minor, such as localised itching, but in more severe cases it causes anaphylaxis, a condition which can lead to upper respiratory obstruction and collapse and can be fatal.

CAUSES

The most common causes of allergic reactions are:

Pollen from trees and grasses

Proteins secreted from house dust mites

Moulds

Foods such as peanuts, tree nuts, milk and eggs

Pets such as cats and dogs, and other furry or hairy animals such as horses, rabbits and guinea pigs

Insects such as wasps and bees

Medicines (these may cause reactions by binding to proteins in the blood, which then trigger the reaction).

WHAT HAPPENS

When a person comes into contact with a particular allergen they are allergic to, a reaction occurs. This begins when the allergen (for example, pollen) enters the body, triggering an antibody response. When the allergen comes into contact with the antibodies, these cells respond by releasing certain substances, one of which is called histamine. These substances cause swelling, inflammation and itching of the surrounding tissues, which is extremely irritating and uncomfortable.

SYMPTOMS

Sneezing

Wheezing / coughing / shortness of breath

Sinus pain / runny nose

Nettle rash / hives

Swelling

Itchy eyes, ears, lips throat and mouth

Sickness, vomiting & diarrhoea

ANAPHYLAXIS

Anaphylaxis is a life threatening severe allergic reaction. It is a medical emergency, and requires immediate treatment. A severe allergic reaction can cause an anaphylactic shock and must be treated with an Adrenaline Auto Injector (AAI).

DIAGNOSE 

The first step in managing an allergy is identifying the cause(s) of the problem. Diagnosing allergy can be difficult since the symptoms may be similar to other conditions. 

If you think you may be allergic to something and do not know what it is, you should start to keep a record of your symptoms. In particular, the following information may help your doctor make a diagnosis:

Do your symptoms occur at any particular time of the day?

Do you only get symptoms at certain times of the year?

Do you suffer more at night time or during the day?

Do your symptoms occur when you are in the house as well as outside?

Does exposure to animals bring on your symptoms?

Do you think that any food or drink brings on your symptoms?

Do the symptoms occur every time you come into contact with the allergen?

Do your symptoms improve when you are on holiday?

TESTING

Skin prick testing

Skin prick testing is one of the most common allergy tests. It involves putting a drop of liquid onto your forearm that contains a substance you may be allergic to. The skin under the drop is then gently pricked. If you’re allergic to the substance, an itchy, red bump will appear within 15 minutes.

Blood tests

Blood tests may be used instead of, or alongside, skin prick tests to help diagnose common allergies. A sample of your blood is removed and analysed for specific antibodies produced by your immune system in response to an allergen.

Patch tests

Patch tests are used to investigate a type of eczema known as contact dermatitis, which can be caused by your skin being exposed to an allergen. A small amount of the suspected allergen is added to special metal discs, which are then taped to your skin for 48 hours and monitored for a reaction.

Elimination diet

If you have a suspected food allergy, you may be advised to avoid eating a particular food to see if your symptoms improve. After a few weeks, you may then be asked to eat the food again to check if you have another reaction.

Challenge testing

In a few cases, a test called a food challenge may also be used to diagnose a food allergy. During the test, you’re given the food you think you’re allergic to in gradually increasing amounts to see how you react under close supervision. This test is riskier than other forms of testing, as it could cause a severe reaction, but is the most accurate way to diagnose food allergies. - Source: https://www.allergyuk.org

DID YOU KNOW?

Immunotherapy

Immunotherapy, often referred to as desensitisation, usually involves the administration of increasing doses of allergen extracts over a period of time.