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The powerful antibiotic penicillin, discovered by chance by scientist Alexander Fleming in 1928, has been prescribed by clinicians for more than 75 years.

While its efficacy is well-documented, about 10 percent of Americans report having a penicillin allergy. For these patients who don’t want to risk an allergic reaction, doctors will typically prescribe “broad-spectrum” antibiotics as an alternative.

In a report published in The BMJ, researchers say they have found a number of alarming issues surrounding the use of broad-spectrum antibiotics, particularly for those who report having a penicillin allergy.

What’s more, many experts state that the vast majority of patients who report having a penicillin allergy can actually take penicillin safely.

In the study, a group of researchers from Massachusetts General Hospital analyzed a medical record database of 11 million patients in the United Kingdom, including patients with a documented penicillin allergy as well as those without an allergy.

They found that those who had a documented penicillin allergy were 69 percent more likely to develop a Staphylococcus aureus (MRSA) infection and 26 percent more likely to develop a Clostridium difficile infection.

The researchers concluded that those with a documented penicillin allergy were more likely to be prescribed broad-spectrum antibiotics as an alternative — and, in turn, these alternatives are associated with a higher risk of nasty bacterial infections.

The trouble with broad spectrum

“When we skip from what would be considered the gold standard or first-choice medication, which for many infections still is something in the penicillin family, many times we’ll use broad-spectrum antibiotics as an alternative,” explained Dr. Kara Wada, assistant professor of allergy and immunology at The Ohio State University Wexner Medical Center.

Wada says that broad-spectrum antibiotics are aptly named because they’re a fairly blunt tool that can wipe out not only bacterial infections, but also some of the beneficial microbiomes in the gastrointestinal system.

“The other thing that we see with some of the broad-spectrum antibiotics is that they’re not as efficient at killing bacteria as penicillin,” continued Wada. “So they treat the infection but not quite as well. That’s where we get concerned that we may end up with some of the more resistant bacteria, such as MRSA in particular, which is what they looked at in this reference study.”

Simply put, broad-spectrum antibiotics generally aren’t as effective as penicillin when it comes to wiping out bacterial infections.

Additionally, by their very nature, their approach is less targeted, which can contribute to antibiotic resistance.

Do you really have a penicillin allergy?

With the issues surrounding broad-spectrum antibiotics, it would appear to be a no-brainer for people to be treated with something in the penicillin family instead.

However, millions of Americans have a documented penicillin allergy, meaning that broad spectrum is the next option when it comes to treating an infection.

Those with allergies to anything, whether it’s a certain food or a drug, know that their condition calls for caution when it comes to potential exposure to the allergen.

But a number of studies indicate that, while 10 percent of Americans have a documented penicillin allergy, around 90 percent of these people can in fact be safely treated with penicillin.

“Penicillin allergy, in many patients that I see, tends to be diagnosed when they’re pretty young,” Wada told Healthline. “These patients have this worry that if they’re exposed to penicillin again that they have the potential for having a life-threatening allergic reaction. I think what we’ve found as allergists in the last few years is that sometimes the label of penicillin allergy may actually create more risk due to the alternative antibiotics than the risk of evaluating and figuring out if you truly are allergic or not.”

Still, a small percentage of people could have a life-threatening anaphylactic reaction to penicillin. So how do these people, and their doctors, determine if they can safely take penicillin or not?

Wada says her job as an allergist makes her an allergy detective, parsing which patients can and can’t take a certain antibiotic.

She says she starts by asking patients with a reported penicillin allergy about the adverse reactions they’ve had in the past. This can often be a tough task, as many are too young to recall what specifically happened.

“Depending on that history and what we are able to sort out from talking to the patient, we do have some tools in our allergist’s toolbox where we can do either skin testing or, in some cases, skip to just giving the patient a small dose of something like amoxicillin and watching them closely when they have exposure,” she explains.

“Then, as long as they tolerate the skin testing and that dose of medication without problems, we’re able to de-label a person of their allergy,” she adds. “That testing procedure of doing skin testing followed up by oral amoxicillin has about a 99 percent chance of ruling out that a patient’s going to have an allergy if they’re exposed again.”

It’s important to note that penicillin allergy is a real, albeit overreported, risk — and anyone who has had a documented adverse reaction to penicillin in the past should be mindful when receiving an antibiotic prescription from their doctor.

That said, given the increased risk of infection that broad-spectrum antibiotics carry, it’s worth talking to your doctor if you have a documented penicillin allergy.

“I think that patients should bring it up with their primary care doctor, that they’ve heard that this may create some problems in the future, and depending on that discussion, it may be worth referral to a board-certified allergist to help sort out if they’re allergic or not,” said Wada.

“In general, we try to be good stewards of antibiotics by using the right drug for the right condition, and not using antibiotics when they’re not indicated,” she said.