Allergy Testing
Allergy, Asthma & Immunology
When possible, it is usually recommended to find, confirm and/or verify an allergen which has induced an allergic reaction. Possible allergens amendable for testing includes, but is not entirely limited to airborne allergens, food allergens, stinging insect allergens (order of insects termed Hymenoptera), penicillin along with allergic contact allergens. Sometimes it’s appropriate to do “panels of allergens” such as airborne allergy testing in individuals with allergic rhinitis, asthma, and/or atopic dermatitis type symptoms, while other times panels of allergy testing are usually not appropriate such as with foods (in which case it is almost always appropriate to perform tests on individual food(s) based on a history of an allergic reaction). The history should be coupled with the test results to given the provider the best chance to find true positive results as opposed to false positive or in less common situations, false negative tests.
Until allergists can determine these things, they can’t recommend appropriate avoidance or the best treatment for relieving the symptoms. Knowing the appropriate and true allergic sensitivities allow the allergist to advise correct avoidance measure(s) and choose the correct treatment.
Allergy Skin Testing
In the skin prick test and the scratch test, an allergist introduces tiny amounts of allergens through the skin. The tests are used to identify allergies to such things as food, pollen, dust mites, mold, pet dander, specific food(s) and/or Hymenoptera venom/imported fire ant.
What to expect
The patient may be asked to refrain from taking certain medications, called antihistamines, before testing. The allergist will place identifying marks on the patient’s arm or back. Tiny amounts of different allergens will be placed on the skin and then devices administer small amounts of potential allergen(s) just under the top portion of the skin. The allergist waits about 15 minutes and then measures/records the size of the localized reaction.
Risks
There is a small chance that skin testing may cause mild allergy symptoms such as watery eyes, congestion, and itchy skin, which generally go away in an hour or two. Also, the bumps or redness at the sites could remain for several hours. The most severe risk is an anaphylactic reaction, which could be life-threatening. The allergist will have epinephrine on hand to treat this.
Understanding the results
Swelling or redness indicate that a person is allergic to that substance. No reaction is considered a negative result — no allergy. Doctors may recommend a further test, an intradermal test in which a tiny amount of an allergen is injected within the skin, to confirm this result.
Allergy Patch Testing
Patch testing exposes a patient’s skin surface to small amounts of potential allergic contact allergens that may cause allergic reactions, such as textile dye, fragrances, latex, medications, metals, topical cream components, and hair dyes.
What to expect
The allergens are placed on the patient’s arm or back, each one covered with a patch. In 48-72 hours, the patient returns to the allergist’s office to have the patches removed. The skin under certain patches may be itchy, red, and/or bumpy, possibly indicating an allergy. Patients return to the office 2-5 days after having patch tests were removed so the allergist can check for reactions that were slower to develop.
Risks
Patients may feel soreness or itchiness while the patches are on, but must keep them on and keep them dry. Also, the patches themselves may irritate a patient’s skin, but that generally clears up within a few days. For patients who have psoriasis, there is a risk that the test can cause flare-up. There is a chance of blisters forming and in uncommon situations, scaring may occur.
Understanding the results
Swelling, redness, and/or bumps/blisters may indicate that a person is allergic to that substance.
Penicillin Allergy Testing
About 10% of the United States Population lists penicillin as an allergy, but only 1 in 10 people who list penicillin as an allergy are actually allergic to penicillin. Moreover, 80% of people with an immediate allergic reaction to penicillin will lose that allergy after 10 years. As per the updated 2022 Drug Allergy Parameters, penicillin allergy should be proactively evaluated for and when appropriate, after any reassuring needed tests, removed from an allergy list.
As per the American Academy of Allergy Asthma and Immunology (AAAAI) Penicillin Allergy Position Paper “A penicillin allergy label is associated with poor patient outcomes including increased hospital length of stay, increased perioperative infections, and overall increased mortality. Use of alternative antibiotics can be associated with higher costs (due to use of more expensive broad-spectrum antibiotics), inferior efficacy and/or greater risk for untoward effects including antibiotic resistance, Clostridium difficile, and side effects. Penicillin allergy testing is associated with significantly less health care utilization over the next several years and greater use of narrow-spectrum antibiotics. Penicillin allergy testing has a very favorable cost-benefit ratio for the incremental cost of testing versus future health care utilization. Delabeling penicillin allergy is an important component of antibiotic stewardship and is endorsed by many professional organizations and public health bodies”
What to expect
Penicillin allergy testing in many cases encompasses taking amoxicillin in the allergist office and being monitored for approximately 2 hrs. In some cases, preceding allergy skin testing, skin prick testing and intradermal allergy testing to penicillin G and the major metabolite called Pre-Pen ® may be needed before an oral challenge with amoxicillin.
Risks
When 2022 Drug Allergy Guideline recommendations are followed, risks are considered minimal.
Understanding the results
Depending on the oral challenge results, and, when needed, the allergy skin testing, the Allergist will discuss further recommendations, but the majority of time individuals who arrive “labeled penicillin allergic” are reassured.
Schedule Your Allergy Test
The allergy and immunology specialists at Florida Medical Clinic will evaluate your medical history and conduct various tests to determine what could be triggering your symptoms. Then, we’ll work with you to develop a management plan based on your diagnosis and treatment goals so you can get back to enjoying your life. Click here to schedule an appointment.
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