How do allergies relate to the immune system?

Allergies are related to the immune system as they are essentially overreactions of the immune system to harmless substances.

Allergies occur when your immune system, which is your body's defence against harmful substances such as bacteria and viruses, mistakenly identifies a harmless substance as a threat. This substance is known as an allergen. Common allergens include pollen, dust mites, mould spores, pet dander, food, insect stings, and certain medicines.

When you come into contact with an allergen, your immune system's reaction can inflame your skin, sinuses, airways, or digestive system. The severity of allergies varies from person to person and can range from minor irritation to anaphylaxis — a potentially life-threatening emergency.

The process begins when an allergen enters the body, triggering an antibody response. The antibodies attach themselves to specific white blood cells. This triggers the release of certain chemicals, including one called histamine. Histamine is responsible for many of the common symptoms of an allergic reaction, such as a runny nose, itchy eyes, and skin rashes.

The immune system's response to an allergen is to produce more of the specific antibody every time it encounters the same allergen. This means that the allergic reaction may become more severe with each exposure. This is why people can suddenly develop allergies to something they have been exposed to many times before.

In summary, allergies are a result of the immune system's overreaction to harmless substances. The immune system mistakenly identifies these substances as threats and responds by producing antibodies. These antibodies trigger the release of chemicals that cause the symptoms of an allergic reaction.