People have allergies because their immune systems react abnormally to harmless elements in the environment. Instead of just ignoring those elements, the body overreacts to them in ways that induce irritation and misery.
The substances that cause allergic reactions are called allergens. Allergens may include foods, medicines, plant pollen, and dust. Allergies are a major cause of illnesses worldwide. In the U.S., up to 50 million Americans, both adults and children, have some type of allergy. Among school children, allergies account for more than 2 million missed school days every year.
An allergy is the overreaction of the immune system to an allergen. The immune system considers the allergen to be a harmful foreign body that it fights off, resulting in symptoms that may range from simply annoying to life-threatening.
The immune system attempts to protect the body by making immunoglobulin E (IgE), an antibody. The antibodies release chemicals, such as histamine, into a person’s bloodstream as protection against what the immune system perceives to be invaders. It is the release of the chemicals that accounts for the allergic reactions that affect the eyes, throat, skin, lungs, and gastrointestinal tract. In the future, exposure to that same allergen will trigger another allergy attack.
Some allergies occur only at certain times of the year. People with an allergy to various pollens react during the months and weeks when those pollens are most prevalent. This type of allergy is called a seasonal allergy. Other people may be allergic to things that are present year-round such as pet dander, dust, and certain types of food.
Foods that commonly trigger allergies include cow’s milk, eggs, fish and shellfish, peanuts and tree nuts, soy, and wheat. People can also be allergic to insect bites, medicines, and some types of chemicals.
A person’s tendency to develop allergies is often hereditary. As a general rule, if one parent is allergic, a child has a 50 percent chance of inheriting the allergy. If both parents are allergic, that figure jumps to 75 percent or higher. Further studies have shown that mothers are more likely to pass their sensitivities on to their daughters and fathers are likely to pass theirs on to sons. Parents don’t necessarily transfer specific allergies. Rather, they pass on the general tendency to be allergic. A family link has been particularly well-established with allergy symptoms such as eczema and asthma.
There are exceptions to the rule. Not all children of parents with allergies develop symptoms themselves. And even a person whose parents did not have allergic sensitivities can develop allergies. If you find yourself suffering from allergies, see an allergy doctor about allergy immunotherapy through allergy shots or sublingual allergy immunotherapy (allergy drops).