Allergy

An allergy is a mistake made by your immune system. Usually, your body protects you from germs that cause sickness. In an allergy, your body thinks a harmless thing is a threat. We call these harmless things allergens.

This mistake can lead to many different allergic diseases. Some people get hay fever or itchy eyes. Others might face asthma or skin problems like eczema. These reactions can affect many parts of the body at once.

There is a specific way this reaction works inside you. First, tiny parts in your blood called IgE antibodies find the allergen. These antibodies attach to special cells called mast cells or basophils.

This connection tells the cells to release chemicals. One important chemical is called histamine. These chemicals cause the symptoms you feel. They might make your nose run or your skin swell.

People have studied these reactions for a long time. The word "allergy" was first used by Clemens von Pirquet in 1906. Scientists now know that many things can cause these reactions. Allergens can be things you breathe, eat, or touch.

Common triggers include pollen, dust mites, and certain foods. Some people also react to insect stings or materials like latex.

Allergies are very common in the world today. About 20% of people in the developed world have allergic rhinitis. Food allergies affect 10% of adults and 8% of children.

In the United States, crustacea is a common food allergy. Many children can even outgrow peanut allergies over time. Egg allergies also affect about one to two percent of children.

Doctors have many ways to help people with allergies. They can use skin or blood tests to find the cause.

One way to treat allergies is to avoid the allergen entirely. People can also use medicines like antihistamines or steroids. For very severe reactions called anaphylaxis, doctors use injectable adrenaline. Some people try immunotherapy to help their bodies adjust. This method slowly exposes a person to small amounts of an allergen.