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.
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.
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:
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.
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.