Mosquitoes are not deterred by simple body lotion; they are repelled by specific volatile chemical compounds that interfere with their ability to sense humans. These insects locate their blood meals primarily by detecting carbon dioxide and various odors on the skin, such as lactic acid. The most effective lotions and sprays contain active ingredients that confuse the mosquito’s olfactory system, essentially making the person invisible. Selecting products with reliable ingredients and understanding the correct application procedure is the foundation for preventing bites and ensuring lasting protection.
EPA-Approved Active Ingredients
The most widely recommended mosquito repellents rely on synthetic compounds registered by the Environmental Protection Agency (EPA). These ingredients are the gold standard for robust, long-duration protection, especially where mosquitoes carry disease. The most established is N,N-Diethyl-meta-toluamide, commonly known as DEET, in use since the 1950s.
DEET-based products block the receptors on the mosquito’s antennae that detect human odors. The concentration determines the duration of protection, not the strength of the repellency. A higher concentration lasts longer, though a 20% product repels insects just as well as a higher concentration.
Picaridin, a synthetic compound mimicking a substance in black pepper plants, is another highly effective alternative. It provides long-lasting protection comparable to DEET and is often preferred because it is nearly odorless and non-greasy. Unlike DEET, Picaridin does not damage plastics or synthetic fabrics.
A third synthetic option is IR3535, based on an amino acid and used in Europe for over two decades. This ingredient is odorless and non-greasy, offering protection for several hours. While effective and considered safe for adults and children, users should avoid contact with the eyes as it can be an irritant.
Understanding Botanical Repellents
For consumers seeking plant-derived protection, Oil of Lemon Eucalyptus (OLE) is the only botanical repellent recommended by the Centers for Disease Control and Prevention (CDC) and registered with the EPA. The active component in OLE is p-Menthane-3,8-diol (PMD), which is chemically synthesized from the oil of the Eucalyptus citriodora leaves.
PMD has demonstrated efficacy comparable to products containing low concentrations of DEET, providing protection for up to six hours. It is important to distinguish OLE products from unrefined lemon eucalyptus essential oil, which lacks the necessary concentration of PMD for reliable, long-lasting protection.
Other common essential oils, such as Citronella, Geraniol, and Peppermint, offer only a short period of repellency. They evaporate much more quickly than PMD or the synthetic compounds. Citronella, for example, requires frequent reapplication, often every hour, to maintain effectiveness.
The protection offered by these less-refined botanical products is often too short-lived to be a reliable defense against disease-carrying mosquitoes. OLE is the exception because it is processed to concentrate the PMD, providing a longer-lasting barrier.
Safe and Effective Application Methods
The method of application significantly affects the effectiveness and safety of any repellent. The product should only be applied to exposed skin and clothing, never underneath clothing. Use just enough product to lightly cover the skin, as heavy saturation does not increase protection.
If sunscreen is used, apply it first, allow it to dry, and then apply the mosquito repellent over it. This order is advised because insect repellent can reduce the sun protection factor (SPF) of sunscreen. For the face, spray the product into your palm first, and then sparingly apply it, avoiding the eyes and mouth.
Special considerations apply to children, who should never handle the product themselves. Adults should apply the repellent to their own hands first and then rub it onto the child’s exposed skin, avoiding their hands. DEET products are safe for infants over two months, but OLE/PMD should not be used on children under three years old.
For comprehensive protection, clothing and gear can be treated with Permethrin, an insecticide designed for fabric. Permethrin remains effective through several washings and provides an excellent barrier against mosquitoes that might otherwise bite through clothing. After returning indoors, treated skin should be washed with soap and water to remove the repellent.