Summer is coming, which means mosquito season is soon upon us. While synthetic insect repellents are still considered the gold standard, concerns about skin irritation and environmental effects have fueled growing interest in natural alternatives.

A study found that patchouli oil may be just as effective as standard insect repellents.

How It Works

The findings, published in ACS Omega, showed that patchouli oil added to a lotion carrier provided complete protection against mosquitoes for up to three hours.

Patchouli oil’s earthy scent appears to work by blocking mosquitoes’ ability to detect human skin, effectively acting like an “invisibility cloak,” according to study lead author Lizandra Lima Santos, a chemist at the Federal University of Amapá in Brazil.

Previous plant-based repellents, such as citronella and eucalyptus, appear to work in a similar way, but they tend to lose their smell more quickly.

Patchouli oil has the same limitation, but Santos’ team solved it by mixing the oil with an unscented cream base, creating a stable lotion that retains its scent over time.

Volunteers ages 20 to 35 placed their arms into cages containing 50 hungry Aedes aegypti mosquitoes for 30 minutes. The test ran for three hours across six 30-minute intervals, with researchers recording every landing and bite. A commercial DEET-based repellent served as the benchmark for comparison.

Before testing, volunteers were instructed not to use moisturizers or other topical products for 12 hours.

Lima Santos said that the high level of protection at low doses was surprising because natural repellents often need higher amounts to work as well as synthetic options. The study did not specify the exact dosage of the patchouli oil used.

It is worth noting that the trial’s narrow volunteer demographic and controlled lab conditions mean real-world results could vary. Researchers said further safety testing is planned before any commercial development.

“So observing complete protection for three hours was particularly encouraging,” Santos said in a press statement.

The Environmental Protection Agency (EPA) has evaluated DEET extensively and concluded that products containing it do not present a health concern to the general public—including children and pregnant women—when used according to label instructions.

A Caution for Sensitive Skin

Despite the promising results, dermatologists urge caution.

Patchouli oil, like many essential oils, is a documented contact allergen and can “certainly” cause allergic or irritant-type dermatitis on the skin, Dr. Tanya Kormeili, a board-certified dermatologist in Santa Monica, California, who was not involved in the study, told The Epoch Times.

“It presents as redness, itching, scaling, swelling, and rarely, even blistering,” she said, adding that reactions may be more severe in people with eczema or sensitive skin. Repeated exposure may also worsen reactions over time.

Kormeili noted that people with eczema, fragrance allergies, or a history of reactions to essential oils are especially at risk. She recommends patch-testing any essential oil on a small area of skin first before wider use.

She also recommends applying DEET or essential oils to clothing rather than directly to the skin, which minimizes exposure and can increase the insect-repellent effect.

How to Repel Mosquitoes

Dr. Shamsa Kanwal, a board-certified dermatologist and consultant at MyPsoriasisTeam.com, who was not involved in the study, offered several recommendations to avoid mosquito bites this summer.

• Use an EPA-registered insect repellent.


• Wear long sleeves and pants in mosquito-heavy areas.


• Avoid peak mosquito activity times when possible.


• Remove standing water near the home.


• Use screens on open windows.

Some people can experience large local reactions to mosquito saliva, Kanwal said. If bites cause severe swelling, fever, spreading redness, breathing symptoms, or repeated intense reactions, she recommends speaking with a doctor to develop an effective mosquito-bite prevention and treatment plan.