Penicillin Allergy Testing

Do you claim to have a penicillin allergy? Have you been tested? Chances are you are not actually allergic…

It is well known that up to 90% of patients who claim an allergy to penicillin are not truly allergic when assessed by formal testing. This means almost 9 out of 10 patients who claim to have a penicillin allergy can safely take penicillin and related antibiotics. Learning if you are allergic now is important for when penicillin-based products are needed.

Penicillins are a safe, effective antibiotic class that have fewer side effects than many stronger alternatives. It is also a very affordable treatment and in many states, free!

How could I NOT be allergic?

Over reporting of penicillin allergy is common and happens for many reasons. The first reason is symptom confusion. A rash originally thought to be caused by penicillin products may have been caused by the illness for which you were being treated. Many kids experience hives related to infections – the same situation when penicillin antibiotics are used. A second common reason is immune system changes. Many patients outgrow allergies as their immune system matures. So even if you were actually allergic in the past, you may not be now. Many patients, unfortunately, claim a penicillin allergy their entire life when their original reaction occurred only when they were a few years old.

Why does it matter?

As stated above, penicillin-based antibiotics are safe and effective. They are what we call ‘narrow-spectrum’ antibiotics, which means they represent a minimally invasive antibiotic that can still appropriately treat your infection. In addition, this concept means penicillin medications less often foster antibiotic resistance, which can ultimately make it harder for your body to fight infections! Again, penicillin medications are cheap and sometimes free!

Get Tested Now!

Michigan ENT & Allergy Specialists is proud to offer this service to its patients. It is important to pursue this testing when you are feeling well before you get sick or need hospitalization.

Here is how penicillin allergy testing works. In our office, a trained allergy nurse performs three stages of penicillin testing.

  1. The first is called Prick Testing. This involves placing both liquid penicillin formulations and control liquids on your skin and pressing them firmly into the top layers of your skin. If you react on the skin in this stage, a penicillin allergy is confirmed, and all remaining testing stops. This phase takes approximately 20 minutes.
  2. If you do not react, our allergy nurses move on to Intradermal Testing. This stage is when five, small superficial injections are used to place both penicillin formulations and a normal saline control just underneath the surface of the skin. This is usually done on the upper arm. Again, we wait for any reactions. If you react, a penicillin allergy is confirmed, and all remaining testing stops. This phase takes approximately 20 minutes.
  3. Finally, if you do not react to any of the skin testing above, we move on to the third phase of testing called Oral Challenge. This is used to confirm negative skin test results. This involves two small doses of oral amoxicillin with a waiting period of 60 minutes to follow. If no reactions occur, we can confirm that you are not allergic to penicillin and you are free to take penicillin-based medications. If you are allergic in this stage, most reactions are mild and include itching, hives, or other systemic symptoms. Emergencies are rare and we are prepared to intervene if necessary. All of our testing takes place with skilled allergy clinicians nearby. If your child is undergoing testing, we do have the capacity to order liquid amoxicillin for the oral challenge portion of the testing.
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