An allergy is an abnormal response of the body's immune system when exposed to something that is usually harmless. Nearly anything can trigger an allergic reaction. Allergies affect 20 percent of Americans.

Here are some common allergens and how to manage them:

1. Pollen

Pollen from weeds, grass and trees commonly trigger seasonal allergies or hay fever. Sneezing, runny nose and itchy, watery eyes are common symptoms. Over-the-counter and prescription antihistamines and decongestants and a series of allergy sensitizing shots can help to control or eliminate symptoms. Staying inside with the windows closed and air conditioning on is also effective, though not always easy.

2. Animal Dander

Animal skin and saliva (dander) secrete protein-containing oils, which can cause an allergic reactions in many people. Those with a known sensitivity should not have a furry pet. If there is someone in your house with allergies, it is important to keep animals out of the bedroom and off of carpets and furniture. Try to bathe pets weekly to control allergic reactions and symptoms.

3. Insect Stings

Swelling, redness, pain and/or itching at the site of an insect sting are common allergic reactions. Do not wear bright colored clothing or fragrances when outside to help avoid stings. Insect repellent can be helpful. Bee, wasp and yellow jacket stings commonly cause anaphylaxis, which can swell the throat and cause breathing difficulties, requiring emergency medical attention.

4. Dust Mites

Microscopic dust mites are found indoors, usually in carpets, upholstery, drapes and bed coverings. They thrive in humid conditions and feed on dead skin cells from humans and animals. Dustmite allergies are bothersome all year and mimic pollen allergies. To protect against dust mites, cover mattresses, box springs and pillows with dust mite protective covers. Use hot water to wash bed linens weekly and keep the house free of dust-collecting items like curtains, carpets and stuffed animals.

5. Mold

Mold triggers allergic symptoms like seasonal allergies but can also be experienced all year, especially if mold is found in the home. Damp areas like basements and bathrooms, and activities like leaf raking and grass cutting, should be avoided to prevent mold exposure.

6. Latex

Exposure to gloves, condoms and medical supplies or equipment containing latex can trigger mild to serious allergic reactions. A rash, runny nose and wheezing are presenting symptoms.

7. Food

Milk (dairy), nuts, shellfish and wheat are common food allergies. An allergic reaction usually transpires within minutes of ingesting the allergen. Known food allergens should be avoided.

8. Medication

Common drug allergies include penicillin, Sulfa drugs and other antibiotics and aspirin. Hives, itchy eyes and throat, or tongue swelling are frequent reactions, but can evolve into anaphylaxis. Mild reactions can respond to antihistamines or a course of steroids.

It is important to note that allergic reactions can vary from mild to anaphylaxis, which requires an immediate injection of epinephrine followed by emergency transportation to a medical care facility.

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