Study: Lemon Eucalyptus Oil More Effective Than DEET Mosquito Repellent

Mosquitoes are among the most deadly disease vectors in the world. The Zika virus, currently making headlines in Central and South America due to its potential for causing severe birth defects if pregnant women are infected, is just the latest in a long roster of mosquito-borne diseases, such as chikungunya, dengue, West Nile, Japanese encephalitis, and yellow fever. Worst of all is malaria, which kills over a million people every year.

To avoid these debilitating illnesses, most conventional mosquito-prevention advice guides people toward DEET, a powerful chemical repellent. However, research suggests that natural solutions can be even more powerful. A pair of studies found that lemon eucalyptus essential oil can be equally or even more effective at warding off mosquitoes than DEET.

The lemon eucalyptus tree (Corymbia citriodora) is native to north eastern Australia. Via: alybaba | Shutterstock.

In one study, published in the Journal of the American Mosquito Control Association, researchers tested the effectiveness of three different types of eucalyptus-based repellent against Anopheles gambiae and Anopheles funestus mosquitoes, two of the breeds that carry the deadly malaria parasite in Sub-Saharan African. Subjects put the product on their legs and feet and found that it protected them completely from mosquito bites for 6 to 7.75 hours, matching the performance of DEET.

Another study, conducted by the London School of Hygiene and Tropical Medicine, tested a mix of 30 percent lemon eucalyptus essential oil against two other natural repellents in addition to DEET. The various mixtures were put on trial against Anopheles darlingi, the mosquito that is the primary vector of malaria in Bolivia. Two of the natural repellents, one made from the Neem tree and another from a mix of essential oils, were found to be ineffective at preventing mosquito bites. A 15 percent DEET compound performed better, providing about 85 percent protection from bites. However, the lemon eucalyptus oil was the best repellent of the bunch, resulting in 97 percent protection over four hours.

Lemon eucalyptus oil is believed to work because its main active ingredient, p-menthane-3,8-diol or PMD, blocks mosquitoes from sensing human presence, masking signals like carbon dioxide and lactic acid. If you purchase repellent that is labeled PMD, it could indicate it contains the natural essential oil itself, or a synthetic mimic of the same chemical. PMD can cause irritation if it gets in the eyes but is rated in the “least-toxic” category by ChemicalWatch.

That’s welcome news for people who would rather avoid DEET, which can cause skin irritation and in rare instances has been implicated in seizures. Other research has suggested that extended exposure to the repellent could be a factor in insomnia, mood disturbances and impaired cognitive function. It has also been linked to neurological damage in children.

The next time someone turns their nose up at eucalyptus oil and insists that DEET is the only way to prevent bug bites, tell them that the natural solution actually outperformed the chemical in a scientific study. If you are heading to a tropical country and need to protect yourself from disease, or simply want to avoid pesky bites during picnics and barbeques this summer, there’s good reason to consider trying out some lemon eucalyptus essential oil and discover its impressive mosquito repellent qualities for yourself.