Why do we get allergies?
Allergies happen when the immune system mistakes a harmless substance, such as pollen, dust mites or peanuts, for a threat and overreacts, releasing chemicals like histamine.
The first time a person with an allergy is exposed to an allergen, their immune system makes antibodies called immunoglobulin E, or IgE. These attach to mast cells in the skin, airways and gut. The next time the allergen appears, the mast cells release histamine and other chemicals, causing sneezing, itching, swelling, rashes or wheezing.
Allergies often run in families, but genes are not the only factor. Some scientists support the hygiene hypothesis, which suggests that less exposure to germs and nature in early childhood may make the immune system more likely to overreact. Pollution and changes in diet may also play a role.
Severe reactions
Most allergies are mild, but some can cause anaphylaxis, a life-threatening reaction that can make the throat swell and blood pressure drop. It needs emergency treatment with adrenaline, often given by an auto-injector. Allergy tests and treatments like immunotherapy can help manage allergies.
Did You Know?
Hay fever, an allergy to pollen, has nothing to do with hay and rarely causes a fever. The name dates from the 1800s, when symptoms were linked to the hay harvest.
This answer is general information, not medical advice. For a personal health question, talk to a doctor.