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Medication and Drug Allergy Testing

Medication Allergies

Skin Testing and Medication Challenge

Did you know that about 1 in 10 people in the U.S. have been told they have a penicillin allergy? Penicillin is one of the most effective and popular antibiotic medications, so it may come as no surprise that penicillin allergies are one of the most commonly reported drug allergies.

But studies show that well over 80% of patients who reported a penicillin allergy in childhood are no longer allergic as adults. When evaluated by an allergist, less than 1% of the population demonstrates a true allergy to penicillin and related antibiotic drugs.

You may ask yourself, Can’t I just avoid penicillin? Aren’t there plenty of alternative antibiotics available? While there are many types of antibiotic treatments available, penicillin and related drugs are often the best treatment for a particular infection. And alternative medications — such as broad-spectrum antibiotics — can carry an increased risk for antibiotic resistance.

What medications commonly cause allergic reactions? What are the symptoms of a medication allergy?

Several types of medications are common triggers for drug allergies:

  1. Penicillin and related antibiotics (such as amoxicillin, nafcillin, oxacillin)
  2. Aspirin, ibuprofen and NSAIDs (nonsteroidal anti-inflammatory drugs)
  3. Sulfa drugs, or antibiotics that contain sulfonamides
  4. Chemotherapy drugs

The most common symptom of a penicillin allergy is an itchy rash that breaks out a few days into the course of treatment. Many patients don’t even remember this experience because it often occurs in early childhood.

Other symptoms of a drug allergy include:

  1. Hives, or intensely itchy raised areas on the skin
  2. Wheezing or difficulty breathing
  3. Swelling
  4. Vomiting
  5. Signs of anaphylaxis, a severe and potentially life-threatening reaction usually marked by impaired breathing, dizziness, fainting, swelling, and rapid heart rate

How will an allergist test for medication allergies?

Diagnosing medication allergies may involve one or more methods, including a detailed patient history, skin test and drug challenge.

Tell your doctor everything you can about the reactions you have had to drugs in the past, including what you suspect may have caused it, when the reaction happened, and the symptoms you experienced. Some drugs, like chemotherapy drugs, cause very clear allergic reactions — in those cases, an understanding of your history may be all that’s needed to determine the presence of an allergy.

Your allergist may recommend a skin test for common medication allergies such as penicillin. The skin test is a painless procedure where a tiny needle, or lancet tip, is used to apply a small amount of the allergen to the upper layers of your skin. After a 15-minute wait, your allergist will read the results and determine next steps.

After a negative skin test, your allergist may recommend a drug challenge to completely rule out the allergy. This is done at a Hudson Allergy location where a nurse will administer a dose of the medication and watch for a possible reaction. A negative result from a drug challenge indicates that you are not allergic to the medication.

As always with any allergy testing, it’s important to avoid use of any antihistamine medications for up to five days before your test. Ask your doctor for more information.

How can I treat my medication allergy? 

If your allergist determines that you have a medication allergy, they may recommend a drug desensitization procedure. Depending on the medication, it may also be possible to simply avoid the allergen in the future.

If you believe you may have a medication allergy, make an appointment at Hudson Allergy to learn more.


Hudson Allergy is New York City’s best Allergy Practice with offices located in:

  • Tribeca

    49 Murray Street
    New York, NY 10007

    208 5th Avenue
    New York, NY 10010
  • Grand Central

    485 Lexington Avenue
    New York, NY 10017