A retro fragrance ingredient once hugely popular with men in the 1960s could help keep mosquitoes at bay, scientists say.
Researchers in Brazil have found that patchouli oil – the musky, earthy scent used in perfumes, aftershaves and skincare products for decades – provided complete protection against mosquitoes for up to three hours in laboratory testing.
The oil, derived from the leaves of the patchouli plant, was formulated into a topical cream and tested against Aedes aegypti mosquitoes, the species responsible for spreading diseases including dengue fever, Zika, chikungunya and yellow fever.
After volunteers applied the cream to their forearms, the researchers found it prevented the mosquitoes from even landing on the skin for the full three-hour test period.
The findings raise the possibility that patchouli oil could one day provide a natural alternative to chemical insect repellents such as DEET, which some users say causes skin irritation, redness and blistering.
Patchouli became especially associated with men’s fragrances in the 1960s and 1970s thanks to its heavy, woody scent, though it remains widely used in modern perfumes, body oils and cosmetics today.
The researchers believe the repellent effect may come from patchouli alcohol – a compound that makes up around 40 percent of the oil and gives it its distinctive smell.
‘Unlike many natural repellents that lose effectiveness quickly due to volatility, our formulation achieved complete protection against A. aegypti for up to three hours at a relatively low concentration,’ said lead study author Lizandra Lima Santos, from the Federal University of Amapá in Brazil.
Patchouli oil provides an earthy fragrance and can be found in body oils, lotions and skincare products (stock image)
The study, published in the journal ACS Omega, used a cream containing patchouli oil at a concentration of just 200 parts per million – equivalent to 0.02 percent of the formula.
By comparison, DEET-based repellents typically contain concentrations ranging from four percent to 100 percent.
In the experiment, adult volunteers applied 1mL of the cream to their forearms before exposing them to 50 female mosquitoes. Researchers checked every 30 minutes for bites.
The team believes compounds in the oil, including alpha-guaiene and beta-elemene, may interfere with proteins involved in how mosquitoes identify human targets.
One compound, alpha-guaiene, appeared to bind to mosquito proteins in a similar way to DEET, reinforcing its potential as a natural repellent, the researchers said.
The cream also remained stable over 90 days under different storage conditions, with no changes in colour, smell or texture.
However, the scientists stressed that further studies are needed before the product could be widely used, including toxicology and clinical safety testing.
Health officials stress that, despite interest in natural alternatives, Americans should still use proven insect repellents to protect themselves from mosquito-borne diseases.
The CDC says EPA-registered repellents containing ingredients such as DEET, picaridin and oil of lemon eucalyptus are ‘proven safe and effective’ when used as directed.
Mosquitoes can spread illnesses including West Nile virus, dengue fever, Zika and chikungunya – some of which can cause severe neurological complications, birth defects or, in rare cases, death.
Experts also advise wearing long sleeves and trousers outdoors, particularly at dawn and dusk when mosquitoes are most active, and removing standing water from gardens and yards where the insects breed.
While DEET has faced periodic safety fears online, the EPA says the ingredient has been reviewed extensively and remains safe for consumers when used correctly.
