Why Should I Test for Penicillin Allergies?

By Pinnacle Allergy

Why should I test for a penicillin allergy?

Taking action to get tested for a penicillin allergy can have an impact on your health, safety, and wallet. According to the Centers for Disease Control and Prevention, 10 percent of the population reports a penicillin allergy, but less than 1 percent truly is allergic.

Penicillin allergy is an abnormal reaction of your immune system to the antibiotic drug, which is prescribed for treating various bacterial infections. Common signs and symptoms of penicillin allergy include hives, rash, and itching. Some symptoms, such as diarrhea and localized skins rashes, are common when taking antibiotics. They frequently are misdiagnosed as an allergy.

When a penicillin allergy is reported, health care providers have to substitute different antibiotics, often using broad-spectrum antibiotics, which are antibiotics that treat many more bacteria than what might be causing the infection. The use of broad-spectrum antibiotics in patients labeled “penicillin-allergic” is associated with higher health care costs, increased risk for antibiotic resistance, and unsatisfactory antibiotic therapy. Broad-spectrum antibiotics often are more expensive and can have more side effects.


Approximately 80 percent of patients with a severe penicillin allergy lose their sensitivity after 10 years. Determining that a patient is not actually allergic to a medication can allow for better treatment options and targeted therapy, and a decrease in hospital stays and medication costs.


Any patient with a history of a reaction to a penicillin antibiotic or who cannot use certain antibiotics out of concern for such reactions should be tested. Patients with known anaphylactic reactions to penicillin in the past five years should not be tested, but if it has been over 10 years since your reaction, you should discuss testing with your provider.


A doctor will use an FDA-approved allergy skin test for the diagnosis of penicillin allergy. Penicillin skin testing involves applying skin prick and intradermal tests, and positive and negative control. The test sites are examined for a reaction, and if the testing is negative, he or she will perform an oral challenge.

In an oral challenge, penicillin or amoxicillin usually is given to confirm that the patient can safely take the medication. The oral dose may be needed because medical tests, including skin testing, are rarely 100 percent accurate. The entire process takes about an hour.

Adela Taylor, M.D., is a physician who sees patients in Allergy & Asthma, in Eau Claire, Wisconsin.

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