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What is Causing Your Allergy?

Allergic reactions are caused by substances in the environment known as allergens. Almost anything can be an allergen for someone. Proteins are organic substances which contain hydrogen, oxygen and nitrogen, and form an important part of all living organisms. There are also found in food, along with fats, carbohydrates and other substances. However, only proteins can cause true allergic reactions.

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 You Have an Allergic Reaction?

When a person who is allergic to a particular allergen comes into contact with it, an allergic reaction occurs. This begins when the allergen (for example, pollen) enters the body, triggering an antibody response. The antibodies attach themselves to special cells, including cells called mast cells. 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.

Common symptoms associated with allergic conditions include:

  • sneezing
  • wheezing
  • sinus pain
  • runny nose
  • coughing
  • nettle rash / hives
  • swelling
  • itchy eyes, ears, lips throat and mouth
  • shortness of breath
  • sickness, vomiting & diarrhoea
  • increase in nasal and airway secretions

There may be many reasons why you may experience any of the above symptoms, however, if you think that you have an allergy or an intolerance you should seek advice from your GP.

How to Help Your Doctor Diagnose an Allergy

The first step in management of allergic disease is identifying the cause(s) of the problem. In some cases, this may be obvious. However, in other cases it may require detailed investigation and medical tests. Diagnosing allergy can be difficult since the symptoms may be similar to other conditions. You may be referred by your GP to a specialist allergy service, our helpline can tell you where your nearest specialist clinic is and give you details to take to your GP. 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. This will help you to find out what you may be allergic to. Keep a diary of when your symptoms occur. In particular, the following information may help your doctor make a diagnosis

  • Do they 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?

Once the offending allergen is identified, avoidance measures can be taken and the most appropriate treatments can be commenced.

Our telephone helpline is a source of information and immediate support. We can supply an information pack of useful information on your particular allergy. Our Nationwide Support Contact Network provides a valuable source of assistance for people with allergy.


Last updated: June 2013                               Next review date: June 2016
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