Your doctor will ask you a series of questions about your exposure and reactions to various allergens as well as collect a full personal and family medical history to identify and help you avoid causes of your allergies or rule out other disorders, which can mimic allergic reactions. You may be asked to keep track of potential allergens and your allergic reactions for a week to help in diagnosis. After this, your doctor will choose a testing method.
The most common test for respiratory, penicillin, insect sting, skin, and food allergies is a skin prick or scratch test. A small amount of the allergen is lightly scratched on the skin using a small plastic device, and the doctor watches for swelling, itchiness, and redness in the skin at the site of the scratch. Other tests look for certain markers in the blood such as IgE antibodies associated with allergies. It's important to note that results from different laboratories or different testing methods may differ. Your doctor can help you know which tests are best for you and help you understand what the results mean.
The most effective treatment for allergies is to avoid the substances that trigger them, but this can be difficult. The most common medications for allergies are antihistamines, which block the effects of histamine chemicals that cause the allergic reactions. Prescription anti-inflammatory steroid drugs, such as prednisone, may also be used for severe symptoms. In emergency situations -- when anaphylactic shock occurs -- injections of epinephrine can be used to relieve symptoms quickly such as correcting low blood pressure or opening up airway passages. Allergy shots -- also called immunotherapy or allergy desensitization therapy -- may lessen the severity of allergies by introducing small amounts of the offending allergens, such as pollens, in order to help the body become more tolerant of the specific allergens, but may require up to one year to become effective.
Skin allergies: Atopic and contact dermatitis can be treated with a variety of anti-inflammatory steroids, usually hydrocortisone, either applied to the skin or sometimes taken by mouth. Mild cases of hives and angioedema often need no medication, but significant or bothersome cases may require antihistamines, or steroid pills. Stomach medicines that have some antihistamine effect, such as ranitidine, may be used as well.
Respiratory allergies: Hay fever can be generally treated with an antihistamine (such as over-the-counter loratadine), but when symptoms persist, your doctor may prescribe a nasal corticosteroid spray. Nasal corticosteroids are typically more effective over the long term but must be used regularly. Another class of drug used for allergic rhinitis or hay fever is the leukotriene receptor antagonist, taken orally every day. Also, allergy shots have a high success rate for treating allergic rhinitis (hay fever) after one year of treatment.