Oil of Lemon Eucalyptus is a plant-based substance shown to be as effective as low concentrations of DEET in repelling mosquitoes. The natural product is derived from eucalyptus leaves and twigs, however it is synthesized for commercial production. It has a pleasant fragrance and sprays containing lemon eucalyptus are far less likely to irritate the skin than DEET repellents.
In two recent studies, oil of lemon eucalyptus (also known as p-menthane 3,8-diol or PMD) was found to offer protection similar to low concentrations of DEET when tested against mosquitoes found in the USA. It has not yet been tested against mosquitoes which spread Malaria or other diseases found internationally, so repellents containing Picaridin or DEET are recommended for use in those regions. It should not be used on children under 3 years of age.
Tests show no adverse effects other than eye irritation - when applying these products you should be careful not to get any of the substance in your eyes. It is advisable not to use it on the hands of children who might rub their eyes or faces.
In general, a repellent with 30% Lemon Eucalyptus oil will provide protection about equal to repellents containing 10%-15% DEET. One comparison test produced the following results:
Off Skintastic for Kids - 4.75% DEET – 88.4 minutes protection time
Repel Lemon Eucalyptus Insect Repellent - 120.1 minutes protection time
Off Deep Woods - 23.8% DEET – 301.5 minutes protection time
Testing has shown it to be the most effective herbal mosquito repellent, outlasting citronella and soy-oil products. Oil of Lemon Eucalyptus provides protection from mosquitoes, biting flies and gnats. Repel® lemon eucalyptus spray claims to also repel deer ticks (carriers of Lyme Disease) for up to 6 hours.
For short-term protection from mosquito species found in the USA, oil of lemon eucalyptus sprays and lotions are an effective alternative to repellents containing approximately 6.65% to 15% DEET.