DEET is the most effective and widely used insect repellent in the world, with over 60 years of use backing its safety and performance. Available in concentrations ranging from less than 10% to over 30%, it protects against mosquitoes, ticks, and other biting insects. The concentration you choose determines how long that protection lasts, not how strong it is.
How DEET Actually Works
For decades, scientists debated exactly how DEET keeps mosquitoes away. Recent research from Auburn University has clarified the picture by identifying two specific smell receptors in mosquitoes that detect DEET directly. One receptor, called OR54, responds exclusively to DEET and appears to serve as a dedicated warning signal. The other, OR55, normally helps mosquitoes detect human body odor but also picks up DEET at moderate levels. When researchers knocked out the DEET-specific receptor in lab mosquitoes, the insects showed a significant drop in their ability to detect the repellent.
In practical terms, DEET works by hijacking the mosquito’s sense of smell. Rather than making you invisible, it activates a repellent signal that overrides the attraction to your skin. This dual-pathway detection, through both a specialized DEET receptor and an odor receptor, helps explain why DEET is so consistently effective across different mosquito species.
How Concentration Affects Protection Time
A common misconception is that higher DEET concentrations repel bugs more powerfully. They don’t. What higher concentrations do is extend the duration of protection. A product with 10% DEET protects for roughly 2 hours, while 30% DEET can last 6 to 8 hours or longer. Beyond about 30%, the gains in duration flatten out, which is why most health agencies don’t recommend concentrations above 30% for everyday use.
Choose your concentration based on how long you’ll be outside. A quick walk around the neighborhood calls for a lower-concentration product. A full day of hiking or camping warrants 20% to 30%. If your activity runs longer than the product’s protection window, reapply according to the label rather than reaching for a higher concentration upfront.
DEET vs. Other Repellents
Picaridin and oil of lemon eucalyptus (OLE, sometimes listed as PMD) are the two main alternatives to DEET. Newer repellents like these may have a lighter feel on the skin and less odor, but none have been shown to outperform DEET overall.
Picaridin at 20% concentration is roughly comparable to 20% DEET against major mosquito species, offering 8 to 14 hours of protection. At 10%, that drops to about 3.5 to 8 hours. Some studies have found picaridin’s protection time to be slightly shorter than DEET’s, but the gap is small enough that picaridin remains a solid choice for people who dislike the feel or smell of DEET.
Oil of lemon eucalyptus at concentrations of 20% to 26% can match 15% to 20% DEET against both mosquitoes and ticks. At 30% concentration, it provides complete protection for about 4 to 6 hours. The tradeoff is that OLE requires more frequent reapplication than DEET. It also should not be used on children under 3 years old.
Using DEET on Children
DEET is safe for children older than 2 months when used correctly. The maximum recommended concentration for infants and children is 30%. For babies younger than 2 months, DEET should not be used at all. Protective clothing and mosquito netting are better options for newborns.
When applying repellent on a child, adults should spray it on their own hands first, then spread it onto the child’s exposed skin. Avoid the hands, eyes, mouth, and use it sparingly around the ears. Children should not handle or apply repellent themselves. A light, even coating on exposed skin is enough. There’s no benefit to saturating the skin, and doing so increases the chance of irritation.
DEET During Pregnancy
DEET is considered safe during pregnancy. The UK Teratology Information Service recommends DEET at up to 50% concentration as the first-line repellent for pregnant women at any stage, particularly those traveling to areas with malaria or other insect-borne diseases. The available human data don’t raise concerns about harm to the developing baby, and the benefits of preventing insect-borne illness clearly outweigh theoretical risks.
If you can’t tolerate DEET during pregnancy (some women find the smell more bothersome than usual), picaridin at 20% or oil of lemon eucalyptus are considered acceptable alternatives. Animal studies on these alternatives have not shown developmental toxicity, though human pregnancy data are more limited than for DEET.
Applying DEET With Sunscreen
If you need both sun protection and bug protection, apply sunscreen first and let it absorb into your skin, then apply DEET-containing repellent on top. This order matters because DEET can reduce sunscreen effectiveness if it’s applied underneath.
Combination sunscreen-repellent products exist but create a practical problem: sunscreen needs reapplication every two hours, while DEET lasts much longer. If you start with a combination product, reapply with a sunscreen-only product at the two-hour mark rather than layering on more repellent you don’t need yet. For most outdoor situations, keeping the two products separate gives you better control over both.
Application Tips for Best Results
Apply DEET only to exposed skin and the outside of clothing. Putting it under clothing traps the chemical against your skin without adding any repellent benefit. Spray it in a light, even layer rather than dousing yourself. More product does not mean more protection.
Avoid applying DEET to cuts, wounds, or irritated skin. When you come indoors, wash treated skin with soap and water, and launder any treated clothing before wearing it again. DEET can damage certain plastics, synthetic fabrics, and leather, so keep it away from watch faces, sunglasses, and gear with plastic coatings.
DEET is available as sprays, lotions, and wipes. Lotions and wipes give you more precise control over where the product goes, which is especially useful for children or for applying near the face. Aerosol sprays cover large skin areas quickly but should be used in well-ventilated spaces and never sprayed directly at the face. To protect your face, spray your hands and then rub it on.