# Formulation and evaluation of topical essential oil lotion as repellent against Aedes aegypti

## TL;DR

A new essential oil lotion was developed and tested as a safe and effective mosquito repellent against Aedes aegypti, showing strong protection for up to 3 hours.

## Contribution

A novel essential oil blend lotion was formulated and shown to provide sustained, safe repellency against Aedes aegypti mosquitoes.

## Key findings

- The lotion showed no skin irritation in 16 volunteers during patch testing.
- The lotion provided >90% repellency against Aedes aegypti for 3 hours.
- Mean repellency of 96.17% was achieved with biting rates below 14% at 3 hours.

## Abstract

Mosquito-borne diseases, particularly dengue transmitted by Aedes aegypti, remain a major public health challenge, underscoring the urgent need for safe and effective plant-based repellents. We developed and evaluated a new lotion containing 15% w/w of a blend of citronella, patchouli, and sage essential oils, focusing on both skin safety and repellent efficacy. Skin compatibility was confirmed in 16 volunteers via patch testing at 30 min, 48 h, and 96 h post-application, with no irritation or allergic reactions observed. Repellent activity was assessed using the WHO-recommended Arm-in-Cage (AIC) method. The lotion achieved a mean complete protection time (CPT) of 103.13 ± 5.46 min and maintained > 90% protection over 3 h, with repellency rates of 100.0%, 99.41%, 94.19%, and 91.01% at 0, 1, 2, and 3 h, respectively. Across all volunteers, the mean repellency was 96.17 ± 0.81%, while biting rates remained below 14% at 3 h. These findings indicate that the essential-oil blend provides safe, sustained, and effective protection, supporting its potential as a natural alternative to synthetic repellents for personal protection against Ae. aegypti.

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•Essential oil-based lotion developed as a natural mosquito repellent.•Human patch tests showed no irritation or allergic reactions.•The lotion maintains > 90 % repellency against Aedes aegypti for 3 h.•Mean repellency of > 95 % was achieved in Arm-in-Cage testing.•The lotion presents a safe, natural alternative to conventional repellents.

Essential oil-based lotion developed as a natural mosquito repellent.

Human patch tests showed no irritation or allergic reactions.

The lotion maintains > 90 % repellency against Aedes aegypti for 3 h.

Mean repellency of > 95 % was achieved in Arm-in-Cage testing.

The lotion presents a safe, natural alternative to conventional repellents.