Why are people allergic to things?

Find out why your body is sensitive to some substances.

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This question sounds simple, but there’s no simple answer to it. Some people are allergic to things in the air, such as pollen, dust and animal hair. Other people are sensitive to certain foods, like milk, eggs, nuts and shellfish. Yet other people are allergic to the venom of stinging bugs, such as bees, wasps and hornets.

What is an allergy?

When you are allergic to something, your body mistakenly thinks that the thing you are sensitive to is going to cause you harm. This triggers your immune system – the network of cells, tissues and organs that work together to help combat diseases – to start fighting whatever you’re allergic to.

The symptoms that allergies cause could be anything from an itchy nose and sneezing to breathing problems or a skin rash. They are the signs that something is wrong in your body. In the case of serious reactions, people may get a swollen tongue or throat, which can be very dangerous.