Penicillin Allergy: Not as Common as Many People Think

Believing you’re allergic when you’re not may limit your access to helpful medications.

What is penicillin?

Penicillin is one of the first widely prescribed antibiotics. It is a class of medication in the beta-lactam family that is commonly prescribed to treat bacterial infections. It is very effective and is the first line of treatment for many bacterial infections such as ear infections, dental infections, strep throat, etc. Examples of this type of drug include amoxicillin, ampicillin, penicillin vk, Augmentin and more.

What is a true penicillin allergy?

In a penicillin allergy, the body’s immune system incorrectly targets the drug as an invader. This immune response can cause a wide range of symptoms, some of which can be dangerous. It’s important to note that penicillin allergies are not common. Less than 1% of patients experience potentially life-threatening allergic reactions (anaphylaxis) to these antibiotics. Symptoms may include:

• Skin manifestations such as hives or swelling
• Pulmonary manifestations such as wheezing, difficulty breathing, or low oxygen saturation levels
• Cardiovascular manifestations such as low blood pressure, fainting, or chest tightness.

Pulmonary and cardiovascular symptoms, while rare, can be serious and may require emergency treatment. On the other hand, isolated skin symptoms are typically not life-threatening and, in many case, may be due to something else.

What are the chances I actually have penicillin allergy?

Studies have found that an estimated 10% of patients self-report as being allergic to penicillin, but less than 1% are actually allergic. Furthermore, 80% of patients with an IgE-mediated penicillin allergy (such as hives or anaphylaxis) lose their sensitivity after 10 years and may be able to safely take penicillin-based medications.

Why does having a penicillin allergy listed in my medical records matter?

If you actually have a penicillin allergy, it needs to be listed in your medical records so that your providers will know not to administer this class of medications to you.

If you do not have a penicillin allergy, having it listed in your medical record can hurt you and ultimately diminish our ability to combat bacterial infections. At the personal level, if your health record says you are allergic, your doctor will not be able to prescribe penicillin. As a result, you may not receive the most appropriate and cost-effective medication when you need it, which can lead to increased health care costs and longer hospital stays. At the global level, unverified penicillin allergy can lead to higher health care expenditures, higher rates of hospitalization, and increased incidence of Clostridium Difficile (“C-diff”) infections and multi-drug resistant bacterial infections. Unverified penicillin allergy is becoming an increasing cause of public health concern.

Why is antibiotic resistance a big deal?

Antibiotics save millions of lives each year, but bacteria are evolving resistance. We have a range of antibiotics that we use to fight these microscopic organisms, starting with drugs like penicillin and progressing to newer, more expensive, “last line of defense” drugs that we try to reserve for the cases that are hardest to treat. When penicillin is not available as our first treatment of choice, we have to use medications that we would otherwise reserve for more advanced and difficult cases. That means bacteria are exposed to those medications more often and can evolve resistance to them, making these vital medications less effective.

How can I find out if I truly have a penicillin allergy?

Validated skin testing is available to assess penicillin allergy. This includes a scratch (prick) test and if negative, intradermal testing to penicillin and its other components. If the testing is negative, there is a 98% chance that the patient can tolerate penicillin. After a negative test, patients are given a full dose of amoxicillin and monitored in the clinic. After we confirm there is no allergic reaction, penicillin can generally be removed from the patient’s allergy list.

What are my next steps?

Talk to your primary care provider (PCP) if you suspect you may be allergic to penicillin or if you had a mild allergic reaction in the past. If your PCP feels testing is warranted, he or she can refer you to an allergist/immunologist such as myself for testing. We will schedule your appointment, talk with you about your medical history and past experience with penicillin, and conduct testing if warranted.