Allergies, a.k.a. allergic diseases, are a number of conditions caused by hypersensitivity of the immune system to something in the environment that usually causes little or no problem in most people.
An allergy starts when your immune system mistakes a normally harmless substance for a dangerous invader. The immune system then produces antibodies that remain on the alert for that particular substance (the allergen). Such overreaction of your immune system can inflame your skin, sinuses, airways or digestive system.
Common types of allergies include hay fever (a.k.a. allergic rhinitis), food allergies, skin allergies (atopic dermatitis), allergic asthma, and drug allergies.
Symptoms of hay fever include sneezing, itching of the nose; eyes or roof of the mouth, runny or stuffy nose, watery; red or swollen eyes.
Symptoms of food allergies include hives, swelling of the lips; tongue; face or throat, and tingling in the mouth.
Symptoms of skin allergies include itch, redden, flake or peel.
Symptoms of allergic asthma include wheezing, shortness of breath, cough or chest congestion.
Symptom of drug allergies include hives, rash, itch, wheezing and swelling.
A severe type of allergy called anaphylaxis may cause symptoms like trouble breathing, blueness of the skin, dizziness, fainting, anxiety, confusion, rapid pulse, nausea, diarrhea, and other serious conditions. For these severe types of conditions, an immediate medical attention is required.
Percentage of adults who have allergies in the U.S.: 30%
Percentage of children who have allergies in the U.S.: 40%
More than 50 million Americans suffer from allergies each year
Rank of allergies among other leading chronic diseases in the U.S.: 6th