What are allergies?
Allergies are hypersensitivities to substances, known as allergens. Allergens (including foods, pollen and latex) are typically harmless to most people. However, allergic reactions occur in some people when the immune system overreacts to an allergen. These reactions range from mildly irritating, causing symptoms such as a blocked nose, to life-threatening reactions such as anaphylaxis.
Allergies are becoming more prevalent, and an estimated 1 in 4 people in the UK suffer from at least one allergy during their lives .
Children are more likely to suffer from allergies, although they may grow out of an allergy depending on the type. The risk of having an allergy is increased if one or both of your parents have an allergy .
Allergies can also develop later on in life, but scientists are unclear why this happens .
What are the most common allergies?
• Food allergy
• Pollen allergy
• Pet allergy
• Latex allergy
• Mould allergy
• Insect allergy
• Drug allergy
Symptoms of an allergic reaction
Allergic reactions develop within minutes after exposure to an allergen. Symptoms depend on the type of allergen but may include sneezing, red and itchy eyes, swelling of the face, eyes and mouth, vomiting, difficulty breathing or itchy skin.
What happens in the body during an allergic reaction?
During an allergic reaction, the immune system responds to allergens as if they are potential threats, such as bacteria and viruses.
When a person’s body detects an allergen, the first immune response is sensitisation. White blood cells produce a type of antibody called immunoglobulin E (IgE), which is specific to the allergen. IgE antibodies enter the bloodstream and join together with mast cells in tissues, including the respiratory tract, the skin and the gastrointestinal tract .
Upon re-exposure, the IgE antibodies recognise the allergen and mast cells respond by releasing chemicals, including histamines which trigger inflammation and symptoms such as sneezing .
Usually, we rely on this immune response to protect us from harmful substances and the resulting symptoms such as sneezing, and vomiting helps the body to expel the threat. However, allergic reactions are a type of hypersensitivity that causes tissue injury.
Treatments are available for managing allergic reactions which block the effects of histamines and reduce inflammation.
A blood test may be recommended to determine whether you have a specific allergy.
A simple blood test can measure the levels of total IgE antibodies and individual IgE antibodies produced against specific allergens.
We offer allergy panel tests that detect a range of allergies such as those to peanuts, wheat and cat dander, as well as to types of antibiotics such as penicillin.
Check out our ‘Allergy and Nutrition’ section for a test that might suit you.
1. NHS website: https://www.nhs.uk/conditions/allergies/
2. de Jong, N. W. et al. Parental and child factors associated with inhalant and food allergy in a population-based prospective cohort study: the Generation R Study. Eur. J. Pediatr. (2019) doi:10.1007/s00431-019-03441-5.
3. Galli, S. J. & Tsai, M. IgE and mast cells in allergic disease. Nature Medicine (2012) doi:10.1038/nm.2755.
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