There are a number of different allergy-causing substances. The most common include pollen, dust mites, mold, animal dander, insect stings, latex, and certain food and medication. If you have an allergy your symptoms can range from mild eye irritation and congestion to a more severe reaction causing swelling and difficulty breathing. And, if you have asthma, a reaction to any offending allergy-causing substance can worsen your asthma symptoms. But, there are steps you can take to prevent and treat allergy attacks when they occur.

Pollen

Exposure to pollen can trigger hay fever, or seasonal allergies. Symptoms include sneezing, runny nose, nasal congestion, and itchy, watery eyes. Treatments include over-the-counter and prescription antihistamines such as Benadryl, Clarinex, or Allegra, decongestants like Sudafed, nasal steroids like Beconase and Flonase, Nasalcrom and drugs that combine antihistamines and decongestants like Allegra-D, Claritin-D or Zyrtec. Allergy shots, also called immunotherapy, are also an option.

Prevent hay fever symptoms by staying indoors when pollen counts are high, closing windows, and using air conditioning.

Dust Mites

Dust mites are microscopic organisms that live in house dust. House dust is a mixture of potentially allergenic materials including fibers from different fabrics, dander from animals, bacteria, mold or fungus spores, food particles, bits of plants, and others. Symptoms of dust mite allergy are similar to pollen allergy but often occur year round rather than just seasonally. Treatment may include medications such as antihistamines or decongestants.

Prevent dust mite allergy by putting plastic covers over mattresses, using hypoallergenic pillows, washing sheets weekly in hot water and keeping all areas of the house, especially the bedroom, free of dust collecting stuffed animals, curtains, and carpet.

Molds

Molds are parasitic, microscopic fungi with spores that float in the air like pollen. Mold is a common trigger for allergies and can be found in damp areas such as basements or bathrooms, as well as in grass, leaf piles, hay, mulch, or under mushrooms. Symptoms of mold allergies can occur seasonally, especially in the summer and fall or year round if mold is in your home. Symptoms are like those of pollen and dust mite allergies and include sneezing, congestion, itchy and watery eyes, runny nose, and coughing. Treatments are the same as those for dust mites or pollen.

Prevent mold allergies by avoiding activities that trigger symptoms, such as raking leaves. Keep windows and doors closed, and make sure moist places in the home, such as the basement and bathrooms, are well ventilated.

Animal Dander and Cockroaches

Proteins secreted by oil glands in an animal's skin, as well as the proteins present in an animal's saliva, can cause allergic reactions in some people. Allergies to animals can take two or more years to develop and symptoms may not subside until months after ending contact with the animal. Symptoms include sneezing, congestion, and itchy and watery eyes. Treatments include avoiding exposure to animals that cause your allergies when possible. Medications such as antihistamines, decongestants, nasal steroids, or others may be helpful. Immunotherapy may be recommended if your symptoms are chronic.

Cockroaches can cause similar symptoms. The treatments are the same.

Prevent allergies to pet dander and cockroaches by removing the pet from the home, or at least the bedroom. Keep pets off upholstered furniture, wash the pet weekly. Cockroach allergy can be prevented by keeping trash in closed containers and taking it out regularly.

Insect Stings

Everyone who gets stung by an insect will have pain, swelling, and redness around the sting site. However, people who are allergic to stings can have a severe or even life-threatening reaction. Symptoms of insect sting allergy include extensive swelling and redness from the sting or bite that may last a week or more, nausea, fatigue, and low-grade fever. On rare occasions, insect stings may cause a full-body allergic reaction called anaphylaxis. Symptoms of anaphylaxis may include difficulty breathing, hives, swelling of the face, throat or mouth, wheezing or difficulty swallowing, restlessness and anxiety, rapid pulse, dizziness, or a sharp drop in blood pressure. For people who are severely allergic to insect stings, the medicine epinephrine should be administered soon after being stung to prevent the development of a life-threatening situation.

Prevention is the best treatment. Minimize exposure to insects by not wearing brightly colored clothes and scented cosmetics and by keeping insecticide available, wearing shoes outdoors, and avoiding outdoor garbage. If you do get stung, remove the stinger. If you are at risk of anaphylaxis, get an epinephrine injection immediately. An oral antihistamine, like Benadryl, may be taken to reduce itching, swelling, and hives, and a pain-reliever may be taken and ice pack used to dull pain caused by the sting. Occasionally corticosteroid medicines are used to decrease swelling and inflammation.

Allergy shots to prevent insect sting allergies are also available.

Insects that cause allergic reactions include various bees, fire ants, yellow jackets, hornets, and wasps.

Latex

Rubber gloves are the most common offending product for people with a latex allergy, but a latex allergy can also be triggered by latex in condoms and certain medical devices. Symptoms of latex allergy include skin rash, hives, eye tearing and irritation, runny nose, sneezing, cough, wheezing, shortness of breath, and itching of the skin or nose. Allergic reactions to latex can range from skin redness and itching to a much more serious reaction, called anaphylaxis which can cause difficulty breathing, hives, or sudden gastrointestinal problems.

Treatments include removal of the latex product. To relieve symptoms, antihistamines or epinephrine will be given. If you have a latex allergy, it is important for you to wear a MedicAlert bracelet and carry an emergency epinephrine kit at all times. To prevent a latex reaction, sensitive individuals should avoid products containing latex.

Foods

Milk, fish and shellfish, nuts, wheat, and eggs are the most common foods that cause allergies. A food allergic reaction usually occurs within minutes of eating the offending food and symptoms, which can include asthma, hives, runny nose, vomiting, diarrhea, and swelling in the area around the mouth, can be severe. The best treatment is to avoid the offending food altogether; but when exposed, treatment with antihistamines or steroids is recommended. In life-threatening situations, an epinephrine injection is needed to reverse symptoms.

Medication

Some people develop allergies to certain medications, such as penicillin or aspirin. Symptoms can range from mild to life-threatening and can include hives, skin rash, itchy skin or eyes, congestion, and swelling in the mouth and throat. The best treatment of drug allergies is to avoid the offending drug altogether; however, when exposed, treatment with antihistamines or steroids is recommended. For coughing and lung congestion, drugs called bronchodilators may be prescribed to widen the airways. For more serious symptoms epinephrine may be needed.

Reviewed by the doctors at The Cleveland Clinic Department of Pulmonary, Allergy and Critical Care Medicine.

Edited by Charlotte E. Grayson, MD, Feb. 2004, WebMD.

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