Allergy-related symptoms can occur after you are around mold, certain animals or animal hair, dust, and other substances. These substances are usually found indoors and do not cause symptoms for most people.

See also:

• Asthma
• Allergic rhinitis

Allergies occurs when the immune system over-reacts to substances (allergens) that are usually harmless.

When a person with allergies breathes in an allergen, the body releases histamine and other chemicals as part of the immune response. This causes itching and swelling, mucus production, and in serious cases, hives and rashes, as well as other symptoms. Symptoms vary in severity from person to person.

Most environmental allergens contact the skin or eyes, or are inhaled. Therefore, most symptoms affect the skin, eyes, or the breathing passages.

You may develop an allergic reaction to particles that may be in or outdoors. Common allergy triggers include:

• Mold -- Mold spores are carried in the air and may be present all year long. Mold is most common indoors in damp locations such as basements, bathrooms, or washrooms. Fabrics, rugs, stuffed animals, books, or wallpaper can contain mold spores if they are kept in a damp place. Outdoors, mold lives in the soil, on compost, and on damp vegetation.
• Animals -- People who are allergic to certain animals are rarely allergic to the animals' fur or feathers. They are actually allergic to the small scales of skin (dander) that the animal sheds. Some people are allergic to the animal's saliva, particularly cats. Cats have saliva that contains a protein known to cause allergy. You can come into contact with animal saliva if the pet licks you, if you touched the pet after it has groomed itself, or if you touch an object that the animal has recently licked or chewed.
• Dust -- House dust contains tiny particles of pollen, mold, fibers from clothing and fabrics, detergents, and microscopic insects (mites). Dust mites, including small fragments of dead mites, are the primary cause of dust allergy and are found in the highest numbers in bedding, mattresses, and box springs.

A few people develop allergy-like symptoms to other irritants in the environment, including smoke, fumes from industries or cleaning products, tobacco, powder, and laundry detergents.

• Coughing
• Difficulty breathing
• Hives
• Itching of the nose, eyes, throat, or skin
• Rash
• Redness in the eyes
• Runny nose
• Sinus pressure
• Sneezing
• Tearing eyes
• Wheezing

The doctor will perform a physical exam and ask you questions about your symptoms. The history of symptoms is important in diagnosing allergies, including whether the symptoms vary according to time of day or the season and possible exposures such as having a pet in the household.

Allergy testing is done to see identify the specific allergens that are causing your symptoms. Skin testing is the most common and useful method. This may include scratch, patch, or other tests.

If your doctor determines that you cannot undergo skin testing, a RAST blood test (to look for IgE antibodies to a specific allergen) may be helpful.

Having allergies may also alter the results of the following tests:

• WBC count, particularly eosinophil count
• Serum immunoelectrophoresis

The best treatment is to avoid being around molds, dander, dust.

See the following articles for specific treatment options:

• Asthma
• Allergic rhinitis
• Atopic eczema
• Allergic conjunctivitis

Allergy shots (immunotherapy) are occasionally recommended if the substance you are allergic to cannot be avoided and if symptoms are hard to control.

Most symptoms of allergies to mold, dander, and dust can be readily treated, and regular treatment can minimize the symptoms.

In some cases (particularly in children), people may outgrow an allergy as the immune system becomes less sensitive to the allergen. However, as a general rule, once a substance causes allergies for an individual, it can continue to affect the person long term.

The most severe cases of allergic rhinitis from these allergens may require immunotherapy (allergy shots) or removal of tissue in the nose or sinuses.

• Anaphylaxis (a rare but severe allergic reaction)
• Drowsiness and other side effects of antihistamines
• Frequent ear infections (otitis media) in children
• Hives or other skin rashes
• Sinus infections

Call your health care provider if severe symptoms of allergy occur, if previously successful treatment has become ineffective, or if symptoms do not respond to treatment.

Breastfeeding can help prevent and decrease allergies. There is also evidence that exposures to certain allergens in the first year of life may prevent some allergies.

Mold spores are everywhere. You can reduce your exposure to mold by following these steps:

• Keep rooms dry, and use a dehumidifier, if necessary.
• Throw out moldy or mildewed articles (such as books, toys, and shoes).
• Use synthetic fabrics for clothing and household furnishings whenever possible. Disinfect bathrooms, basement walls, and furniture with diluted bleach or other disinfectant solutions.

Clean frequently to reduce dust. Vacuum frequently, preferably using a small-pore filter to capture dust mites. Damp-mop and dust often.

Eliminate as many "dust catchers" as possible, including rugs, bed ruffles or canopies, and curtains.

You can buy special covers for mattresses, box springs, and pillows to reduce dust mites. Wash rugs, bedding, and furniture coverings in hot water (at least 130 degrees Farenheit) weekly if possible.

Central heating and air-conditioning systems may be helpful, particularly if they include special filters to capture dust. Change furnace filters frequently. Use of high efficiency particulate air (HEPA) filters are most helpful in preventing mold exposures.

People who are allergic to animals may need to avoid keeping pets. Frequent bathing and grooming of the pet (preferably by someone who is not allergic to the animal) may help. Allergy to animals may also include wool, which may contain tiny amounts of dander (skin).