An allergy occurs when the body’s immune system responds severely and inappropriately to a stimulant that is often otherwise harmless. The immune system naturally differentiates between “self” and “non-self” molecules. When a foreign invader, such as an allergen (a substance that causes an allergic reaction) invades the body, the immune system attempts to isolate and rid the body of it. Common allergens may include certain foods, such as peanuts or shellfish, airborne allergens including pollen, dust and animal dander, insect stings, medications such as penicillin or aspirin, and surfaces such as latex or nickel. An allergic reaction is triggered immunoglobulin E (IgE), which is an antibody. The antibody-IgE complex causes well-known allergy symptoms such as congestion, runny nose, watery eyes, itchy skin, swelling, hives, cough, chest tightness, shortness of breath, wheezing, and in extreme cases, anaphylaxis. Anaphylaxis is characterized by severe airway constriction, which prevents the patient from breathing, as well as extreme dilation of the blood vessels, causing a decrease in blood pressure.
Atopic patients, those predisposed to allergic hypersensitivity, often have a family history of allergies (such as asthma, hay fever, or eczema) and will usually exhibit a positive skin test. There are two categories of allergens – seasonal and perennial. Seasonal allergens include pollens and occur during the pollination months of plants. Perennial allergens are present year-round, and are often considered “indoor” allergens, such as pet dander, mold, and dust mites. In order to determine which of these you are allergic to, it is possible to do either a skin test or a blood test. A skin test requires the allergen to be put on or into the skin, and changes are observed for 10-15 minutes. Up to 54.3% of US adults have positive reactions to one or more allergens. Once the allergen is determined, several preventative measures can be taken. For example, environmental modifications to remove the allergen or complete avoidance of the allergen can be tried. Medications used to manage allergies include antihistamines, anti-inflammatory medications such as steroids, or decongestants. In times of severe reaction (such as anaphylaxis) it may be necessary to administer epinephrine, which would allow for opening of the airways and restoration of blood pressure.