• pollens
• molds
• house dust mites
• animal dander and saliva (cat, dog, horse, rabbit)
• chemicals used in industry
• some foods and medicines
• venom from insect stings

 

Common allergies
Condition	Triggers	Symptoms
Asthma	A wide range of things can trigger an asthma attack. These include cigarette smoke, viral infections, pollen, dust mites, furry animals, cold air, changing weather conditions, exercise, and even stress.	Coughing, wheezing, difficult breathing; coughing with activity or exertion; chest tightness.
Hay Fever	Pollen from trees, grasses, or weeds.	Stuffy nose, sneezing, and a runny nose; breathing through the mouth because of stuffy nose; rubbing or wrinkling the nose and facial grimacing to relieve nasal itch; watery, itchy eyes; redness or swelling in and under the eyes.
Food allergies	Any foods, but the most common are eggs, peanuts, milk (see information on milk allergies), nuts, soy, fish, wheat, peas, and shellfish.	Vomiting, diarrhea, hives, eczema, difficult breathing, and possibly a drop in blood pressure (shock).
Eczema (atopic dermatitis)	Sometimes made worse by food allergies, contact with allergens (pollen, dust mites, furry animals), irritants, sweating.	A patchy, dry, red, itchy rash that often occurs in the creases of the arms, legs, and neck; however, in infants it often starts on the cheeks, behind the ears, and on the thighs.
Hives	Viral infections, food allergies, and drugs (such as aspirin, penicillin, or sulfa) but cause is often unknown.	Itchy, mosquito-bite-like skin patches that are more red or pale than the surrounding skin. Hives may be found on different parts of the body and do not stay at the same spot for more than a few hours.
Contact dermatitis	Contact with a plant substance such as poison ivy or oak, household detergents and cleansers, and chemicals in some cosmetics and perfumes.	Itchy, red, raised patches that may blister if severe. Most of these patches are confined to the areas of direct contact with the allergen.