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Botanic oil from the tree Eucalyptus citriodora marketed as an insect repellent and having potential antiviral properties. Citriodiol contains the active ingredient p-menthane-3,8-diol (PMD).

Citriodiol is derived form the oil of the native Austrailian tree Eucalyptus citriodora, also known as lemon eucalyptus, and is marketed as an alternative to diethyltoluamide (DEET). Citriodiol has been notified under the European Biocidal Products Directive (BPD) 98/8/EC and began proceeding through the registration process with the Heath and Safety Executive in the UK. Citriodiol contains 64% PMD which is a mixture of cis and trans isomers of p-menthane-3,8-diol. PMD is an active ingredient in insect repellents that smells similar to menthol and acts as a coolant. Citriodiol is the trade name for the PMD Rich Botantic Oil (PMDRBO) and a product of the company Citrefine.

Citriodiol-sprays are known to kill some strains of coronavirus. These repellents were given to British soldiers in the early phases of the COVID-19 crisis. Mosi-guard, a Citriodiol-based spray was tested for efficacy on plastic and on artificial skin by the Ministry of Defence and the results were release in a paper from the Porton Down-based Defence Science and Technology Lab (DSTL). DSTL reported that in lab tests there was some loss of recoverable virus on synthetic latex skin one hour after treatment but that some virus was still recoverable over a four-hour period. Mosi-guard was supplied by the Leeds-based company Citrefine. Citriodiol-based insect repellent may be labelled as “oil of lemon eucalyptus”. Citriodiol could potentially be used as an antiviral agent, disinfectant or substance used for medical treatment.

The patent US7872051B2 “Antiviral composition comprising p-menthane-3,8-diol”, filed by Paul Douglas Clarke, concerns the compound p-menthane-3,8-diol (PMD) which is derived from Eucalyptus citriodora and may be manufactured from a PMD-rich extract such as Citriodiol. PMD is described to have insect repellent properties and antiviral properties.


Further Resources


Experimental survival of SARS-CoV-2 on an insect-repellent-treated surface

Ministry of Defense (UK)


Dan Sabbagh Defence and security editor
August 26, 2020
the Guardian
Army personnel at a Covid testing facility in Darlington. Photograph: Ian Forsyth/Getty Images


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