What is Citriodiol? Insect Repellent Appears to Kill Coronavirus, U.K. Army Scientists Say

Researchers in the U.K. have found a Citriodiol, a product found in insect repellant, can kill the coronavirus that causes COVID-19.

Citriodiol is made by Citrefine International Ltd. It is produced from oil from the eucalyptus citriodora tree. The oil is produced by a process that artificially mimics and accelerates the normal acting process in the leaf, converting it into p-menthane-3,8-diol (PMD), according to the company website. This compound is known to have a repellent effect.

The product has approval from the U.S. Environmental Protection Agency.

Previous research had shown Citriodiol can kill SARS CoV-1, the virus that caused the SARS outbreak in 2004. As a result, the U.K.'s Ministry of Defense were looking to see if it had any effect against the new coronavirus.

In April, Sky News announced the armed forces in the U.K. were to be issued with an insect repellent that contains Citriodiol. Because the repellent has no adverse side effects, it was considered a potential way of giving force members an additional layer of protection against COVID-19.

Now, Sky News has also reported that research into Citriodiol by the U.K.'s Defense Science and Technology Laboratory (Dstl) has found the product does kill SARS-CoV-2, the virus that causes COVID-19.

The report by the Defense Science and Technology Laboratory (Dstl) looked at Mosi-guard Natural spray, produced by Citrefine. The team carried out two experimental approaches. They looked at the anti-viral activity when sprayed directly onto the virus, and how it performed when sprayed onto a latex "synthetic skin."

Tests showed Mosi-guard Natural had anti-viral activity against SARS-CoV-2 when mixed with the virus in the liquid phase. Anti-viral activity was also detected in the latex experiments.

The report noted some caveats. For example, the synthetic skin is a representative surface and human skin may react differently. They also did not test the change in performance over time.

In a statement emailed to Newsweek, Defence Minister Jeremy Quin said: "Dstl's latest research shows that sprays containing Citriodiol, which have been made available to MOD units engaged in the Covid response, can kill the virus. We are sharing our preliminary findings today so others can take forward additional research to confirm and expand on our findings."

According to Sky News, insect repellents that contain Citriodiol—but not Deet—have the potential to protect against COVID-19. The spray is not sufficient to protect against the disease on its own and is being used by the armed forces with other preventative measures, such as PPE and handwashing.

insect repellent
Stock image representing insect repellent. Researchers in the U.K. have found a product in an insect repellent can kill SARS-CoV-2. iStock