The short answer is “yes,” but you may never have been allergic to begin with.

Having a true allergy to penicillin is serious.

However, if you’ve been told you have a penicillin allergy by a doctor who is not an allergist, you may want to confirm the diagnosis.

While 10 percent of the general population reports having a penicillin allergy, “Ninety percent of patients labeled as PCN [penicillin] allergic are not,” Dr. Andrew Murphy, allergist at Asthma, Allergy and Sinus Center in Pennsylvania, told Healthline.

Avoiding antibiotics without knowing if you have an allergy can affect your healthcare, added Dr. David Stukus, pediatric allergist at Nationwide Children’s Hospital in Ohio, and spokesperson for the American College of Allergy, Asthma & Immunology (ACAAI).

Stukus said it has been well documented in multiple research studies that people with reported penicillin allergies receive different care than those who do not report an allergy.

“This includes use of more expensive and less effective antibiotics. It also increases risk for side effects from use of more broad spectrum and less specific antibiotics,” Stukus told Healthline.

Penicillin and its derivatives (including amoxicillin) are first-line therapy for some of the most common bacterial infections, such as ear infections, sinusitis, and pneumonia.

Read more: Get the facts on amoxicillin and penicillin »

One reason many people report being allergic to penicillin might be due to misdiagnosis.

The Mayo Clinic says that common symptoms of a penicillin allergic reaction include the following:

  • skin rash
  • hives
  • itching
  • fever
  • swelling
  • shortness of breath
  • wheezing
  • runny nose
  • itchy, watery eyes
  • anaphylaxis

But many side effects from antibiotics, such as rashes and gastrointestinal issues, are sometimes mislabeled as allergic reactions.

“Children frequently experience rashes when ill, and especially when ill and taking an antibiotic. The vast majority of these rashes are not due to any type of allergic reaction, but are often labeled as such,” explained Stukus. “This reported antibiotic allergy can then remain a part of their permanent health record and rarely, if ever, is clarified.”

“On a population level, this is a widespread and very costly problem,” Stukus also noted.

Read more: Get the facts on allergy testing »

The problem may be compounded because many physicians not fully educated on penicillin allergies treat people diagnosed with the condition, according to a survey conducted by ACAAI.

“Allergy lists are reviewed at every medical encounter and almost all medical personnel, regardless of training, can enter an allergy onto someone’s chart,” said Stukus.

The majority of reported antibiotic allergies are not actually due to an allergic mechanism, meaning a reaction will not happen again with future exposure, or will not progress to any more severe reactions, Stukus added.

“This topic is widely misunderstood by patients and medical providers alike. It is important for anyone with a suspected or reported antibiotic allergy to clarify their status, often through consultation with a board certified allergist, as this will absolutely impact their medical care throughout their lives,” stated Stukus.

Sometimes doctors may not understand that patients should be tested by an allergist to confirm the diagnosis.

In fact, many of the internists and general practitioners surveyed by ACAAI reported they were not aware that a lot of people who state they have a penicillin allergy have never been tested for it.

More than 80 percent of the general practitioners surveyed knew they should refer a patient with a reported penicillin allergy to an allergist, yet they didn’t or had rarely done so.

“Immediate onset, IgE-mediated allergic [anaphylactic] allergies to penicillin often disappear after about 10 years from the last exposure, but may be gone sooner for some,” Stukus said. “This is really important for people to understand as many people continue to report their penicillin allergy throughout their entire life, even if the suspected reaction happened decades ago.”

Stukus recommended getting retested for a penicillin allergy every five to 10 years.

Murphy agreed, stating that an annual allergy test is not necessary.

“For patients who outgrow PCN allergy, this occurs over years to decades. There is some evidence that over time PCN allergy will fade or resolve. That decision could only be made after the patient was seen, evaluated, and PCN skin testing and oral challenge was done and the patient passed,” says Murphy.