Can nasal Neosporin fight COVID? Surprising new research suggests it works

A potential treatment for COVID-19 may have been hiding in our medicine cabinets, a new study in PNAS has found

By Nicole Karlis

Senior Writer

Published April 27, 2024 5:30AM (EDT)

Neosporin is displayed on a store shelf. (Tim Boyle/Getty Images)
Neosporin is displayed on a store shelf. (Tim Boyle/Getty Images)

Four years ago, when COVID-19 first began to spread globally, it didn't just damage our physical health, but also the health of our information ecosystem. Ever since, the internet has been rife with health misinformation on ways to treat or protect oneself against the coronavirus. First, internet healers falsely suggested that gargling salt water and vinegar could prevent a coronavirus infection. Then, despite multiple studies debunking the effectiveness of ivermectin, an anti-parasitic drug used in horses (and less commonly in humans), Joe Rogan fans continued to cling onto it as a potential treatment.

Health misinformation is a symptom of a lack of certainty. When there is no guaranteed preventative measure or treatment, people are bound to find solutions on their own. Thanks to cognitive biases like confirmation bias, they might even appear to work. But what if a way to reduce exposure to COVID-19, and treat it, was hiding in our medicine cabinets all along — and it wasn’t pseudoscience? 

A new study published in the journal Proceedings of the National Academy of Sciences suggests that neomycin, an ingredient in the first aid ointment Neosporin, may prevent or treat a range of respiratory viral infections such as COVID-19 and influenza when applied to the nose. 

In the study, researchers found that mice who had neomycin in their nostrils exhibited strong antiviral activity against both SARS-CoV- 2 and a highly virulent strain of influenza A virus. It also mitigated contact transmission of SARS-CoV- 2 between hamsters. 

"When we compared the gene expression in the nose, Neosporin stimulated genes whereas those people who had Vaseline did not."

“We decided to see if neomycin applied into the nose can protect animals from infection with COVID as well as the flu,” Dr. Akiko Iwasaki, the lead author of the study and a professor of immunobiology at the Yale University School of Medicine, told Salon in a phone interview. “And what we found is that treatment with neomycin significantly prevented infection and also reduced disease burden in animals.”

Iwasaki described the work as “encouraging” because it shows that neomycin can trigger an antiviral response in animals by creating a localized immune response. “That’s resulting in this protection that we see,” Iwasaki said. 

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The results are encouraging for mice and hamsters. But what about humans? The researchers proceeded to recruit healthy volunteers and asked them to apply Neosporin with a cotton swab to their nose, twice a day. The placebo for some was vaseline. The researchers measured their antiviral response and found similar results.

“When we compared the gene expression in the nose, Neosporin stimulated genes whereas those people who had Vaseline did not,” Iwasaki said.  “So this suggests that we might be able to use Neosporin or neomycin in humans to induce this antiviral state that we also saw in animals.”

Does that mean we should all be applying Neosporin to our noses in high-risk situations? Not exactly, but it probably wouldn’t hurt either — as long as someone isn’t allergic to the cream, which is a combination of the antibiotics bacitracin, neomycin and polymyxin B. Notably, details around the dosage remain unclear. 

“We know from the dose response that we did in animals that we probably need to give humans more Neosporin, or neomycin,” she said. “Because Neosporin has very little neomycin compared to what we were able to achieve in the animal model.”

"This could be a potential broad spectrum antiviral treatment and prophylaxis."

Iwasaki added they know that Neosporin can produce a similar effect in humans as it did in animals, but whether or not it can reduce transmission has yet to be determined. 

“For that, we need different kinds of study and a much larger study to determine that,” she said. 

Amesh Adalja, a senior scholar at the Johns Hopkins Center and infectious disease doctor who wasn’t involved in the study, told Salon via email that the research could have broader implications that extend beyond COVID-19. 

“This could be a potential broad spectrum antiviral treatment and prophylaxis,”Adalja said. “The molecules in the topical antibiotic cream induce certain antiviral compounds to be made by cells where the ointment has been applied; these antiviral compounds produce non-specific immunity that impacts various viruses.”

Iwasaki cautioned against the idea that people swabbing their noses with Neosporin will be a cure-all in the future. Instead, she said she sees this as another possible layer of protection

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“We know how important it is to layer protection against infections,” Iwasaki said. “Vaccines and masks and other measures are very important, but this type of strategy where we can trigger the host to produce antiviral factors may be another layer that we can add on to the existing ones.”

The more layers a person has, Iwasaki said, the less likely a person is to get infected. 

“And that's really important for preventing diseases like long COVID,” Iwasaki said, referring to a condition in which COVID symptoms last for months or even years. “So I think it's definitely worth kind of moving forward with an approach like this.”

An approach that was right under our noses all this time.

By Nicole Karlis

Nicole Karlis is a senior writer at Salon, specializing in health and science. Tweet her @nicolekarlis.

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