Asthma and allergies are two conditions which are the result of an overactive immune system. Allergen-induced asthma is the result of allergic reactions triggering asthma. This is the most common form of asthma, according to the Asthma and Allergy Foundation of America, and accounts for 50 percent of all cases of asthma.
Causes
Allergen-induced asthma is the result of problems with an immunological protein known as IgE, the American Academy of Allergy Asthma and Immunology explains. This protein is produced by the body in response to exposure to allergens. When the IgE proteins and the allergens are present together, they release a number of chemical signals, such as histamine, which result in inflammation. This inflammation can affect the respiratory system and result in an asthma attack.
Symptoms
Allergic asthma causes the same general symptoms of asthma, the Allergy and Asthma Foundation of American says. These include shortness of breath, chest tightness or pain and difficulty breathing. The swelling of the airways also can result in a characteristic whistling or wheezing sound when the patient is breathing. Allergic asthma also can result in coughing. One of the hallmarks of allergic asthma is that the coughing and breathing problems can be severe enough that they make sleeping difficult.
Triggers
Allergic asthma requires exposure to an allergen to trigger the allergic reaction that causes the asthma. There are many different allergens that can trigger an asthma attack, the Mayo Clinic says. Some common allergens include dander from pets, dust, mold, smoke and certain kinds of pollen. Patients can be allergic to one or many different allergens, and anything that is able to provoke an allergic response can trigger an asthma attack.
Diagnosis
Asthma is typically diagnosed using spirometry, which is a series of breathing tests that measure lung function. Spirometry can measure how much air a person can inhale and exhale, as well as how fast a person can exhale. Patients who are suspected of having allergic asthma also might need allergy testing, the National Heart Lung and Blood Institute says. Allergy testing can be done by exposing a patient to potential allergens to determine if they are able to elicit an allergic reaction. This is typically done using a "scratch" test, in which a small amount of potential allergens are put on the patient. The skin is then scratched to allow the allergen to get under the skin. Each scratch is then monitored for swelling or redness. Alternatively, a doctor can run blood tests that look for the presence of IgE antibodies to diagnose allergies.
Treatment
Patients with allergic asthma can benefit from avoiding allergens, the Mayo Clinic says. Some allergy medications, such as inhaled corticosteroids, can help patients obtain relief both from asthma and from their allergies. Another kind of therapy, known as immunotherapy, aims to desensitize the immune systems of patients to allergens. This treatment also can help relieve the symptoms of allergic asthma. Patients with allergic asthma also can benefit from montelukast, which inhibits inflammation and will treat both the allergies and the asthma. Patients who suffer from frequent asthma attacks also need to use bronchodilators, which will help keep their airways open.
