Allergies – in a nutshell

A quick catchup on allergies and anaphylaxis - and what to do

The UK has some of the highest rates of allergic conditions in the world. Apparently, 44% of British adults now suffer from at least one allergy and the number of sufferers is on the rise, growing by around two million between 2008 and 2009 alone. Almost half of sufferers have more than one allergy. However, some people can suffer from anaphylaxis.

What is an allergy?

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. When a person encounters a particular allergen they are allergic to, a reaction occurs. This begins when the allergen 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.

What is anaphylaxis?

In most allergic reactions the resulting chemicals are released locally into the tissues in a particular part of the body (skin, eyes, etc.). This means the symptoms of the allergic reaction usually only occur in this area.

In anaphylaxis, the chemicals that cause the allergic symptoms, e.g. histamine are released into the bloodstream. The symptoms of anaphylaxis usually occur within minutes of exposure to the trigger substance (allergen) but sometimes an hour or so later. Anaphylaxis usually develops suddenly and gets worse very quickly. Symptoms include:

  • Feeling light-headed or faint
  • Breathing difficulties – such as fast, shallow breathing and a feeling of choking/closing of the throat
  • Wheezing
  • A fast heartbeat
  • Clammy skin
  • Confusion and anxiety
  • Collapsing or losing consciousness
  • There may also be other allergy symptoms, including an itchy, raised rash (hives), feeling or being sick, swelling (angioedema), or stomach pain.

What to do if someone is having an anaphylactic reaction:

  • Try to ensure that a person suffering an allergic reaction remains as still as possible
  • Preferably they should be lying down and if they are feeling weak, dizzy or appear pale and sweating their legs should be raised
  • When dialling 999, say that the person is suffering from anaphylaxis (anna-fill-axis)
  • Give clear and precise directions to the emergency operator, including the postcode of your location
  • If adrenaline has been given, make a note of the time this was administered. A second dose can be given after five minutes if there has been no improvement
  • If the person’s condition deteriorates after making the initial 999 call, a second call to the emergency services should be made to ensure an ambulance has been dispatched
  • Send someone outside to direct the ambulance crew when they arrive
  • Try to ascertain what food or substance may have caused the reaction and ensure the ambulance crew knows this.

How can I get diagnosed for allergies?

Testing for allergies can be complicated and is not always needed. Medication, including antihistamines, can work well for many types of allergy but some people may need further treatment. Speak to your GP if you think you have an allergy.

Who gets allergies?

Anyone can have an allergy. About half of people with allergy are children. Some people are more prone to allergic problems due to a condition called atopy. Food is a common trigger in children whilst, in older people, medicines are common culprits.

Of course, there are a great many other allergens, too many to list. Most allergens are proteins, but some, e.g. medications are not. These need to be bound to a protein once they are in the body before they can cause an allergic response.

For further information see www.anaphylaxis.org.uk or www.allergyuk.org