DEET remains the gold standard for mosquito repellent, providing over six hours of protection at concentrations around 25%. But it’s not your only option. Picaridin, oil of lemon eucalyptus, and permethrin-treated clothing all offer meaningful protection, and the best choice depends on how long you’ll be outside, where you’re going, and who’s using it.
DEET: The Longest-Lasting Option
DEET has been used since the 1950s and is still the most thoroughly tested repellent available. At 24-25% concentration, it maintains over 90% repellency for six hours, with complete protection times ranging from 300 to 480 minutes depending on the product and formulation. Higher concentrations don’t repel mosquitoes better; they just last longer. A 30% DEET product won’t create a stronger barrier than a 15% one, but it will keep working for more hours before you need to reapply.
For a few hours in the backyard, a 10-15% DEET product is plenty. For a full day of hiking or travel in mosquito-heavy areas, look for 20-30%. There’s no added benefit to going above 30%, and the CDC recommends capping concentration at 30% for children.
Picaridin: Similar Protection, Less Irritation
Picaridin offers protection comparable to DEET without the greasy feel or tendency to damage plastics and synthetic fabrics. A 20% picaridin product provides protection for roughly the same duration as a similar concentration of DEET. It’s odorless, doesn’t feel sticky on skin, and works against both mosquitoes and ticks. If you’ve avoided repellent in the past because you disliked how DEET feels, picaridin is the most practical alternative.
Oil of Lemon Eucalyptus
Oil of lemon eucalyptus (OLE) is the only plant-based repellent that the CDC recommends alongside synthetic options. Its active compound, PMD, provides roughly two hours of protection per application. That’s significantly less than DEET or picaridin, so you’ll need to reapply more frequently. One important restriction: OLE should not be used on children under three years old.
Don’t confuse OLE with pure lemon eucalyptus essential oil. The refined, EPA-registered version contains a standardized concentration of PMD. The essential oil sold for aromatherapy has not been evaluated for repellent use and won’t deliver the same results.
Why Essential Oils Fall Short
Citronella, peppermint, cedarwood, and similar essential oils are popular in “natural” repellent products, but their protection times are dramatically shorter than registered repellents. Citronella oil protects for less than two hours, and the EPA requires citronella-based products to carry a label recommending reapplication every hour. In one head-to-head comparison, citronella’s complete protection time was about 10 minutes compared to 360 minutes for DEET.
The active compounds in these oils evaporate quickly from skin, which is the core problem. Some formulations use fixatives like vanillin to slow evaporation and extend protection, but even with those additions, they don’t approach the duration of DEET, picaridin, or OLE. If you’re sitting on your porch for 30 minutes, a citronella-based product might be fine. For anything longer or in areas with disease-carrying mosquitoes, it’s not enough.
Permethrin for Clothing and Gear
Permethrin is not a skin repellent. It’s a treatment you apply to clothing, shoes, tents, and gear. It kills or disables mosquitoes and ticks on contact with the treated fabric, and it works well as a complement to a skin-applied repellent. You can buy pre-treated clothing or spray your own gear with a permethrin solution.
The tradeoff is durability. After about 16 rounds of machine washing and drying, permethrin concentrations on treated clothing drop by 50-90%, and effectiveness drops noticeably. Factory-treated garments typically last longer than DIY spray treatments. If you treat your own clothes, plan to retreat them after every five or six washes, or follow the product label’s guidance.
Spatial Repellent Devices
Devices like Thermacell work by heating a chemical called metofluthrin, which vaporizes into the surrounding air and creates a zone of protection. These are designed for stationary use: patios, campsites, or picnic areas. In field testing, metofluthrin emanators reduced mosquito landing rates by 85-94% within 10 feet of the device. At 20 feet, effectiveness dropped to about 45%.
These devices work best when you’re sitting still in a defined area with minimal wind. They’re not a replacement for topical repellent if you’re moving around, but they’re effective for creating a comfortable outdoor space.
A Newer Option: 2-Undecanone
A newer EPA-registered repellent derived from wild tomato plants uses 2-undecanone as its active ingredient, sold under the brand name BioUD. In lab testing against ticks, it was two to four times more effective than DEET at comparable concentrations. It’s positioned as a bio-based alternative for people who want to avoid synthetic chemicals but need more protection than essential oils provide. Availability is more limited than DEET or picaridin products, but it’s worth knowing about if you’re looking for plant-derived options with real efficacy data behind them.
Using Repellent With Sunscreen
If you need both sunscreen and repellent, apply sunscreen first and let it dry before applying repellent on top. This order matters because DEET-containing repellents can reduce sunscreen’s effectiveness by roughly 30%. The longer you wait between the two applications, the less interference there is. Waiting about an hour is ideal, though even 15 minutes of drying time helps. Avoid combination sunscreen-repellent products, since sunscreen needs reapplication every two hours while repellent does not, and reapplying both on that schedule means overexposing your skin to repellent chemicals.
Age and Safety Considerations
Babies under two months old should not use any insect repellent. For infants and toddlers older than two months, DEET and picaridin are both options, but keep DEET concentration at 30% or below. Oil of lemon eucalyptus is off-limits for children under three. For young children, applying repellent to your own hands first and then rubbing it on the child’s skin gives you more control and helps keep it away from eyes and mouths.
EPA-registered repellents, when used as directed, are safe during pregnancy and breastfeeding. The CDC’s guidance for breastfeeding mothers is straightforward: use repellent only when needed, follow label directions, wash it off when you come indoors, and keep it away from the nipple area before nursing.
Getting the Most From Any Repellent
Apply repellent to all exposed skin, not just arms and legs. Mosquitoes will find the gaps. Spray it onto your hands first and then rub it on your face and ears rather than spraying directly at your head. Reapply after swimming or heavy sweating, even if the label suggests a longer protection window. Clothing-applied permethrin plus skin-applied DEET or picaridin is the most effective combination for high-risk environments like tropical travel or heavily wooded areas where tick-borne and mosquito-borne diseases are a concern.