Over 50 million Americans suffer from allergies, the American College of Allergy, Asthma and Immunology reports. Many undergo testing each year to determine the substances that trigger their allergic symptoms. Allergy testing, usually done by injecting a small amount of potential allergens into the skin, is performed in the allergist’s office, so that side effects and more severe reactions can be promptly treated. Most side effects of allergy testing last only a short time and have no long term effects, but rarely, severe side effects occur.
Itching
If a person is allergic to a certain substance, the injected or scratched area becomes very itchy. Because the itchiness helps diagnose an allergic reaction, antihistamines, which reduce immune responses such as itching, should not be taken for up to 10 days before allergy testing, MayoClinic.com recommends. Some anti-depressants and heartburn medications can also interfere with test results and should not be taken, depending on your doctor’s advice. Cortisone creams applied to the itchy areas and oral antihistamines help reduce inflammation after the test.
Hives
Hives--raised, reddened itchy welts that look and feel like mosquito bites--appear at the site if a person proves allergic to a certain substance. Hives usually appear within 20 minutes after skin pricks and disappear within a few hours, but may appear for up to several hours after testing and take up to 24 to 48 hours to fade, the American College of Allergy, Asthma and Immunology reports. The larger the bump, the more sensitivity a person has to a specific substance, MayoClinic.com states.
Pain
Most allergy testing hurts only briefly, when the tiny scratch is made, but if allergens are injected under the skin, a method known as intradermal testing, there may be some discomfort. Intradermal dilutional testing, which requires multiple sticks to determine sensitivity levels to certain allergens, may cause more discomfort, according to the University of Texas Medical Branch at Galveston.
Anaphylaxis
Very rarely, severe allergic reaction and anaphylaxis develop during allergy testing. A person may develop swelling on the face, throat, lips and tongue swelling, difficulty breathing, nausea, vomiting and feelings of panic, followed by loss of consciousness and, in rare cases, death, according to the American College of Allergy, Asthma and Immunology. Hives may break out all over the body, not just in the location of the injected allergens. Anaphylaxis, which usually occurs within minutes after an allergic substance is injected, is a true medical emergency that requires injection of medications such as epinephrine to allow the person to breathe. Medications to reduce the immune response, such as corticosteroids and antihistamines, may also be given.
