What is an allergy?

Allergy is the result of the immune system overreacting to harmless stimuli in the environment.

Examples of stimuli or 'allergens' include pollen, dust, eggs and milk.

The body recognises these harmless allergens as foreign, which leads to white blood cells releasing antibodies.

Antibodies then trigger mast cells (another form of immune cell) to produce histamine and this promotes inflammation. You may have seen how inflammation manifests in your own body following injury or infection. Typically the inflamed part of the body becomes hot, red, swollen and very painful.

SK
Answered by Saadiyah K. Biology tutor

4799 Views

See similar Biology A Level tutors

Related Biology A Level answers

All answers ▸

Explain the reflex arc using an example in humans


How are action potentials generated in a neuron?


Explain how the structure of glycogen makes it suitable as a cellular energy store. (3 marks)


How do populations of bacteria develop antibiotic resistance?


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

MyTutor is part of the IXL family of brands:

© 2026 by IXL Learning