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Insect repellent Citriodiol can help kill virus that causes COVID-19, study says. Expert dismisses it as 'today's miracle cure.'

Korin Miller
·6-min read

Disinfectants have been the frontline defense against SARS-CoV-2, the virus that causes COVID-19, on surfaces. But new research suggests there may be another tool people can use: an insect repellent Citriodiol.

Scientists at the U.K.’s Defense Science and Technology Laboratory found in a preliminary study that Citriodiol can help kill SARS-CoV-2. The study specifically analyzed the effects of Mosi-guard Natural insect repellent, which has the active ingredient Citriodiol, against SARS-CoV-2 in a lab setting in two different experiments. In one experiment, the spray was applied directly to the virus; in another, it was sprayed onto a latex synthetic skin.

The studies showed that Mosi-guard Natural had some level of antiviral activity against SARS-CoV-2. However, it was more effective at higher concentrations when it was applied directly to the virus. “There was evidence that the Mosi-guard Natural treatment on latex synthetic skin affected the survival of the virus over a four-hour period,” the study reads. But researchers didn’t compare the spray’s effectiveness to that of disinfectants or soap and water and, it’s worth noting, some of the virus remained on the “skin” after Citriodiol was applied.

Still, the findings raise some big questions about Citriodiol. Here’s what you need to know.

What is Citriodiol?

Citriodiol is the trade name for Eucalyptus citriodora oil hydrated, cyclized, according to Mosi-guard’s website. In the U.S., it’s known as oil of lemon eucalyptus, an ingredient that is registered with the Environmental Protection Agency as a skin-applied insect repellent.

Oil of lemon eucalyptus is an active ingredient in several insect repellents in the U.S., including Repel, Coleman Botanicals and Mosi-guard, per the EPA.

“Citriodiol is made from distilled oil from a particular type of eucalyptus tree, lemon eucalyptus,” Jamie Alan, an assistant professor of pharmacology and toxicology at Michigan State University, tells Yahoo Life. “It’s in natural insect repellants. The active component is a compound called PMD, which is concentrated in the refining process.”

Is Citriodiol safe?

According to the EPA, oil of lemon eucalyptus is safe to use topically as an insect repellent.

“This is usually found in sprays and is marketed as a natural and sustainably-sourced insect repellent,” Alan says. “Allegedly, it also breaks down and does not accumulate in the environment.”

While Citriodiol is EPA-registered, “it is generally felt to be less effective than DEET or picaridin, especially for mosquitos,” John Sellick Jr., a professor of medicine in the Division of Infectious Diseases at the University at Buffalo, tells Yahoo Life.

How to use Citriodiol

When Citriodiol is used as an insect repellent, it’s applied just to the skin, Dr. Amesh Adalja, a senior scholar at the Johns Hopkins Center for Health Security, tells Yahoo Life. But its use to fight COVID-19 is unclear at this point. “I don’t see a big role for this in COVID-19 protection, as we already have alcohol-based hand sanitizers, disinfectants and plain soap and water that achieve the same purpose,” Adalja says.

“There is no apparent use for this chemical in combating COVID-19 at this time,” Dr. Iahn Gonsenhauser, chief quality and patient safety officer at The Ohio State University Wexner Medical Center, tells Yahoo Life. “Because COVID-19 is primarily spread via exhaled droplets expelled into the air and only carries a limited risk of surface contact exposure, using this to disinfect surfaces provides little protection and is no more useful than bleach solutions or other EPA approved surface disinfectants.”

“It’s today’s miracle cure,” Dr. William Schaffner, an infectious disease specialist and professor at the Vanderbilt University School of Medicine, tells Yahoo Life. But while the new study found that Citriodiol had anti-viral effects against SARS-CoV-2, Schaffner is hesitant to say that this point that it will work outside a laboratory setting. “There’s a big difference between a test tube and using it on people in the real world,” he says. “It should be tested on people for this use.”

Based on the study’s findings, “it looks like you can use Citriodiol similar to Lysol spray,” Alan says. “The big difference is that you can spray this on you and on your clothes.”

However, Alan stops short of recommending that people actually use their Citriodiol-containing insect repellent this way. “The data seem a bit shaky,” she says. She also has concerns about spraying insect repellent that contains Citriodiol on countertops. “I worry about vapors in the air, particularly with little kids and pets, and residue being ingested,” she says.

“Their results tell me that oil of lemon eucalyptus isn't as strong as an alcohol-based sanitizer in disinfecting surfaces,” Jason Kaelber, assistant research professor at the Rutgers New Jersey Institute for Quantitative Biomedicine, tells Yahoo Life. “Personally, I'm going to stick with alcohol for disinfecting my skin when I'm not near a sink and I'll use alcohol or other household cleaners for disinfecting surfaces.”

And, of course, you shouldn’t try to consume this. “Certainly don’t spray it in your nose or down your throat,” Schaffner says. “It can cause nausea and vomiting if ingested,” Alan says.

Overall, experts aren’t overly excited about Citriodiol to fight COVID-19. “Wearing a mask and doing good hand hygiene are the keys, not wearing insect repellant,” Sellick says.

For the latest coronavirus news and updates, follow along at https://news.yahoo.com/coronavirus. According to experts, people over 60 and those who are immunocompromised continue to be the most at risk. If you have questions, please reference the CDC’s and WHO’s resource guides.

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