Allergy to mold - dander - dust

A collection of symptoms that occur after exposure to mold, animal dander, dust, or other substances, usually in the indoor environment, that do not cause symptoms for most people (see also asthma ; allergic rhinitis ).

Alternative Names

Indoor allergies; Pet allergies

Causes, incidence, and risk factors

Allergies are caused by hypersensitivity of the immune system, leading to a misdirected immune response . The immune system normally protects the body against harmful substances such as bacteria, viruses, and toxins . Allergy occurs when the immune system reacts to substances (allergens) that are generally harmless and in most people do not cause an immune response. Allergy to environmental particles most commonly leads to allergic rhinitis ( hay fever ). Hay fever usually involves an allergic reaction to pollen. However, people may develop an allergic reaction to other particles in the indoor or outdoor environment that leads to symptoms virtually identical to hay fever. Many people are allergic to mold. Mold spores are carried in the air and may be present all year long. Mold is most prevalent indoors in often damp locations such as swamp coolers, basements, bathrooms, or washrooms. Fabrics, rugs, stuffed animals, books, or wallpaper can also harbor mold spores if they are frequently in contact with water or kept in a damp place. Outdoors, mold lives in the soil, on compost, and on damp vegetation. Dust is another common allergen . House dust contains microscopic particles of pollen, mold, fibers from clothing and other fabrics, detergents , and microscopic insects (mites). Dust mites, including small fragments of dead mites, are the primary cause of dust allergy and are found int the highest numbers in bedding, mattresses and boxsprings. Many people are allergic to animals. Most people are not allergic to the animal's 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 (whose saliva contains a protein known to cause allergy). Saliva exposure occurs if the animal licks the person. It may also occur from petting the animal after it has groomed itself or by touching an object that the animal has recently licked or chewed. A few people develop allergies to other irritants in the environment, including smoke, fumes from industries or cleaning products, tobacco, powder ( face powder , baby powder, and so on), laundry detergents, and other common substances. When an allergen enters the body of a person with a sensitized immune system, it triggers antibody production. Histamine and other chemicals are released by body tissues as part of the immune response. This causes itching , swelling of affected tissues, mucus production, hives and rashes , as well as other symptoms. Symptoms vary in severity from person to person. Most environmental allergens contact the skin, eyes, or are inhaled. Therefore, most symptoms affect the skin, eyes, or the breathing passages. Many disorders are associated with, triggered, or worsened by allergies. These include eczema , asthma , and many others. Allergies are common. Heredity, environmental conditions, number and type of exposures, emotional factors ( stress and emotional upset can increase the sensitivity of the immune system), and many other factors can indicate a predisposition to allergies. For reasons that are not fully clear to scientists, allergies are on the rise, particularly in so-called "Westernized" countries such as the United States.

Signs and tests

  • The pattern of allergic 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.
  • An elevated
  • antibody (particularly IgE) level indicates that the body has developed an allergic immune response. Testing may reveal the specific allergen (s).
  • Skin testing is the most common and useful method of
  • allergy testing . This may include intradermal, scratch, patch, or other tests.
  • RAST (blood test for antibody (IgE) to specific allergen)
  • Occasionally, the suspected allergen is dissolved and dropped onto the lining of the lower eyelid (
  • conjunctiva ) as a means of testing for allergies.
  • Other testing to determine the specific allergen may include various types of "use" or "elimination" tests where suspected items are eliminated and/or introduced while the person is observed for response to the substance.
  • This disease may also alter the results of the following tests:
  • a
  • WBC count , particularly eosinophil count
  • immunoelectrophoresis - serum
  • Treatment

  • The goal is to reduce allergy symptoms caused by inflammation of affected tissues.
  • The best "treatment" is to avoid what causes your allergies in the first place. (See Prevention.) It may be impossible to completely avoid everything you are allergic to, but you can often take steps to reduce your exposure. Medication options include the following:
  • Short-acting antihistamines, which are generally non-prescription, often relieve mild to moderate symptoms but can cause drowsiness. In addition, these antihistamines can blunt learning in children (even in the absence of drowsiness). An example is diphenhydramine (Benedryl).
  • Longer-acting antihistamines cause less drowsiness and can be equally effective, and usually do not interfere with learning. These medications, which require a prescription, include fexofenadine (Allegra), cetirizine (Zyrtec), and loratadine (Claritin).
  • For people with symptoms not relieved by antihistamines alone, nasal corticosteroid sprays are very effective and safe. These prescription medications include fluticasone (Flonase), mometasone (Nasonex), and triamcinolone (Nasacort AQ).
  • Decongestants may also be helpful in reducing symptoms such as
  • nasal congestion , but should not be used for long periods.
  • Cromolyn sodium is available as a nasal spray (Nasalcrom) for treating
  • hay fever . Eye drop versions of cromolyn sodium and antihistamines are available for itchy bloodshot eyes . The most appropriate medication depends on the type and severity of symptoms. Specific illnesses that are caused by allergies (such as asthma , hay fever , and eczema ) may require other treatments. Allergy shots (immunotherapy) is occasionally recommended if the allergen cannot be avoided and symptoms are hard to control. It includes regular injections of the allergen, given in increasing doses (each dose is slightly larger than the previous dose) that may help the body adjust to the antigen .

    Expectations (prognosis)

    Most allergies are readily treated. However, treatment only affects that exposure, so subsequent exposures cause another allergic reaction . People who are allergic to mold may also be allergic to penicillin, which is derived from a variety of mold. They may also be allergic to blue cheese, which is an ingredient of some salad dressings. Some children may outgrow an allergy as the immune system becomes less sensitive to the allergen . This is particularly true of food allergies. However, as a general rule, once substances have provoked allergic reactions they continue to affect the person. Desensitization may cause uncomfortable side effects (such as hives and rash ) and may have dangerous side effects such as anaphylaxis . It often requires years of treatment and is effective in about two-thirds of cases.


  • anaphylaxis
  • (life-threatening
  • allergic reaction )
  • discomfort during the allergic reaction
  • increased
  • incidence of ear infection ( otitis media ) in children
  • chronic
  • mouth breathing with resultant facial changes (children only)
  • disruption of lifestyle
  • drowsiness
  • and other side effects of antihistamines
  • side effects of other medications (See the specific medication.)
  • Calling your health care provider

    Call for an appointment with 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 be effective at preventing and decreasing allergies. There is also evidence that exposures to certain allergens in the first year of life may prevent some allergies. This is called the "hygiene hypothesis" and sprang from observations that infants on farms tend to have fewer allergies than those in environments that are more sterile. Once allergies have developed, avoiding known allergens may decrease symptoms and prevent other allergies. Mold spores are everywhere. Minimize exposure by keeping rooms dry (using a dehumidifier if neccessary). Discard moldy or mildewed articles (books, toys, shoes, and so on). Use synthetic fabrics for clothing and household furnishings whenever possible. Disinfect bathrooms, basement walls, and furniture with diluted bleach or other appropriate disinfectant solution. Clean frequently to minimize 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. Bedding and mattresses harbor dust mites, and special covers for mattresses, box springs, and pillows reduce dust mite allergen. Wash rugs, bedding, and furniture coverings weekly if possible. Central heating and air-conditioning systems may be helpful, particularly if they include special filters to capture dust. 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). Avoid other irritants whenever possible.

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