If you have an allergy, you're in good company. Allergies affect an estimated 50 to 60 million Americans each year. Allergy triggers are as diverse as they are common.
An allergic reaction happens when the immune system, which protects the body from foreign and potentially harmful substances, is overly sensitive to a common substance. Because any substance can be an allergen to someone, the number of allergens is limitless. Some of the more common allergens include pollen, mold, dust, pets, insect bites and certain kinds of food and medications.
When an allergen such as pollen enters the body of a person with a sensitized immune system, it triggers antibody production. Histamine and other chemicals are released by body tissues as part of the immune response. This causes itching, swelling of affected tissues, mucus production, muscle spasms, and other symptoms.
Heredity, environmental conditions, number and type of exposures, emotional factors (stress and emotional upset can increase the sensitivity of the immune system), and many other factors can indicate a predisposition to allergies.
Sometimes children have allergies at birth and through childhood, but may "outgrow" them as they move into adulthood. People can also develop allergies after prolonged exposure to certain allergens. For example, florists can develop an allergy to flowering plants over time. Many people live with allergies their entire lives.
Severe allergies can result in anaphylactic shock and sometimes death. Severe reactions are most common with insect bite, food and medication allergies. If a person experiences a severe reaction, which often includes difficulty breathing and disorientation, he or she should seek immediate medical attention.