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What You Need to Know About Penicillin Allergies

Almost 10% of people have an allergy to penicillin on their active list of allergies, but far fewer are actually allergic. Here's what you need to know about how to test for a penicillin allergy and what getting it off your list can open up for you.


"While an allergy to penicillin is among the most commonly listed drug allergies, a vast majority of patients with a penicillin allergy listed on their medical records can actually tolerate penicillin very well. What you might not know is that having penicillin listed on your medical records as an allergy can lead to unnecessary risk and alternative medications with far worse side effects.

Javen Wunschel DO, an allergist at The Iowa Clinic, says that the reasons a patient may have a penicillin allergy on their list vary, but most of the time it can be removed after a simple test.

“There are a number of reasons it might be on your list even if you aren’t actually allergic, but the two most common reasons are that the symptoms were attributed to penicillin when you weren’t actually having an allergic reaction, and most commonly, people outgrow the intolerance,” Dr. Wunschel says.

How Do I Know If I’m Allergic to Penicillin?

Often, penicillin allergies get put on a medical record when a patient is young. Because of this, many patients never question it or think about getting re-tested. However, there are simple tests that can determine whether you truly have a penicillin allergy.

“It’s important for people to get tested because true penicillin allergies are pretty rare, and if you can get it taken off your list, you really should,” Dr. Wunschel says.

If you’re unsure whether you’re allergic, you can ask your primary care provider about receiving a test.

“True allergies usually have pretty quick reactions; we’ll see it within the first two hours after receiving a dose of penicillin. If you’re truly allergic, we see a whole constellation of symptoms including swelling of the tongue, GI symptoms, rash, hives, the whole nine yards,” Dr. Wunschel says. “If you get tested for a penicillin allergy and are positive, we know that most people outgrow medication allergies within ten years, so we would recommend getting tested again at that time.”

Despite what some patients fear, it’s important to note that penicillin allergies are not hereditary. If you have a relative with an allergy to penicillin, that doesn’t mean that you need to avoid these medications.

Common Conditions Treated by Penicillin

You may be wondering what the big deal is if you have penicillin listed on your allergy list. After all, aren’t there other options out there for treatment?

While there are always alternative options available, penicillin-based antibiotics are sometimes the most effective and targeted treatment available. In fact, penicillin-based treatments are commonly used to treat a wide range of conditions, including:

  • Sinus infection
  • Skin infection
  • Blood infections
  • Pre- and Post-operational antibiotic for surgery

What Risk Does Having a Penicillin Allergy on Your Allergy List Pose?

No matter how the allergy got added to your list, getting it removed might not seem like a big deal. However, patients who can tolerate penicillin-based medications but don’t receive them because of it being listed on their records often have worse medical outcomes as a result.

In reality, 90% of people who have a penicillin allergy listed on their records can tolerate it well without any adverse effects.

“What people don’t realize is that penicillins are commonly used antibiotics and if your body can tolerate it, you should be using them instead of alternatives,” Dr. Wunschel says.

Alternative antibiotics may not work as well, have more severe side effects, or cost more. Beyond that, the risk of infection at a surgery site is higher when alternative medications are used.

“There’s a whole host of risks that come with not using penicillin-based antibiotics where they would most commonly be recommended,” Dr. Wunschel says, “Avoiding penicillin can lead to an increased risk of antibiotic resistance, it can lead to longer hospital stays and raise your chance of post-surgical complications. People sometimes view penicillin as an old-fashioned medicine choice, but we still use it all the time and for good reason. It’s extremely effective.”

Testing for Penicillin Allergies at The Iowa Clinic

If you want to test to eliminate penicillin from your allergy list, there’s good news. At The Iowa Clinic, you can be evaluated for a penicillin allergy at any time. Once you’re referred to an allergist by your primary care physician, the test itself often takes place on the same day you discuss the test procedure and your medical history with the specialist.

Dr. Wunschel says that the three-step process is straightforward and carefully monitored to ensure the safety and comfort of the patient.

“First we scratch the skin with a small piece of plastic to test some proteins within penicillin. The second step is a needle that goes under the skin to test your reaction. If you have no reaction in the first two steps, we will administer a dose of penicillin and monitor you closely for reaction,” Dr. Wunschel explains.

In the event of a positive reaction during testing, anti-allergy medications, epinephrine, and other immediate treatment measures are available and will be implemented as needed.

If you have no reaction to any of the steps of the process, you can have penicillin removed from your allergy list and go back to using penicillin-based medications when they are recommended by your care team.

“There are always alternatives available if you do test positive, but it’s about managing risk, and if you have the ability to take penicillin-based antibiotics, that’s almost always what we would recommend,” Dr. Wunschel says.

At The Iowa Clinic, the Coordinated Care model makes it easy to get tested and for the results of your test to be communicated across departments seamlessly and quickly. Want to learn more about getting tested? Talk with your primary care provider or request an appointment at The Iowa Clinic today.

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