Unnecessary or incorrect use of topical antifungal medications is driving the spread of fungal infections like ringworm, which are becoming more difficult to treat, according to a January 11 study published in Morbidity and Mortality Weekly Report.
If a patient’s condition is not caused by a fungus but is treated as such, treatment will be ineffective.
such as clotrimazole or combinations of antifungals and corticosteroids. And because many topical treatments are also available over-the-counter, doctors should advise patients about how to use them correctly.
“In the last few years, there have been many antifungal resistant cases of tinea corporisand onychomycosisreported,” or ringworm and finger or toenail infections, respectively, said Shari Lipner, MD, PhD, a dermatologist at Weill Cornell Medicine in New York, and an author of the study.
Many of these cases originated in South Asia and have also been reported in Europe and Canada. In 2023, the first cases of a new strain of antifungal-resistant ringworm were reported in the United States. This species, Trichophyton indotineae, does not respond to topical medications, requiring oral treatment instead.
“It’s really a serious problem and a huge public health concern,” Dr. Lipner said.
For the new study, Dr. Lipner and colleagues examined prescription patterns from 2021 Medicare Part D claims of topical antifungals. They report that 6.5 million topical antifungal prescriptions were filled that year, some of which included steroids in the formulation. Primary care clinicians wrote 40% of these prescriptions, the most for any clinician group. The estimate is almost certainly an undercount of topical antifungal use because the database did not include over-the-counter purchases or data from other insurance payers.
The number of prescriptions equate to 1 in every 8 Medicare Part D beneficiary receiving an antifungal, the researchers reported.
“If I think about the patients that come into my office, I’m certainly not giving an antifungal to 1 in 8 of them, and I see a lot of fungal infections,” Dr. Lipner said. The findings suggest to Dr. Lipner that some clinicians are diagnosing ringworm by eyesight alone rather than confirming the diagnosis with techniques such as microscopy, fungal culture testing, or polymerase chain reaction testing.
Sometimes what looks like ringworm may actually be eczema, in which case, the topical antifungal would not be appropriate, according to Avrom Caplan, MD, a dermatologist at NYU Langone Health in New York.
“If you’re prescribing something to somebody that they don’t need, you’re basically exposing them to the side effects without the benefit,” Dr. Caplan, who was not part of the study, said.
Dr. Caplan, who reported the first cases of ringworm that only responded to oral medications in the United States, stressed that topical treatments work fine for many ringworm cases today. But if indiscriminate prescribing spurs the development of more resilient fungi, more situations may arise in which only oral medications work in the future, Dr. Caplan said. In addition, oral medications are inherently more demanding on a patient than something they can rub on their skin, Dr. Caplan added.
“We hope that physicians will really think hard about this study and change their practices if they’re not confirming the diagnosis,” Dr. Lipner said.
Dr. Lipner and Dr. Caplan report no relevant financial relationships.
A version of this article appeared on Medscape.com.