What is an allergy?

Allergies happen when your body is very sensitive to certain substances, called allergens. Hayfever sufferers are allergic to pollen – tiny grass seeds floating in the breeze.

When you breathe in something you’re allergic to, your body thinks it’s under attack. The white blood cells make complicated chemicals called antibodies to try and get rid of it.

When these antibodies start beating up on the allergen, a chemical reaction happens and stuff called histamine gets released. Histamine is what makes you sneeze and have runny eyes. Britain’s 6 million hayfever sufferers get sneezy, wheezy and headachy when they breathe in pollen and other allergens. Other people get all itchy or swell up when they get near cat hair or dust mites.

Normally antibodies are great – they’re your body’s way of protecting itself against bacteria and viruses. But in an allergy they start attacking the wrong target.

Can I catch it?          What can I do about it?