The most effective mosquito repellents work by interfering with a mosquito’s ability to detect you. DEET, picaridin, and oil of lemon eucalyptus (OLE) are the top performers, each providing several hours of protection when applied to skin. But the full picture includes what you wear, what you plug in on your patio, and which popular products are a complete waste of money.
How Repellents Actually Work
Mosquitoes find you primarily by sensing the carbon dioxide you exhale and the chemical cocktail on your skin, including lactic acid and other compounds in sweat. Effective repellents don’t kill mosquitoes or create a force field. They block the mosquito’s smell receptors so it can’t detect those attractant signals. DEET, the most studied repellent on the market, directly inhibits the olfactory receptors mosquitoes rely on to home in on a host. It essentially makes you invisible to their nose. Picaridin and IR3535 work through similar sensory disruption, though through slightly different chemical pathways.
Skin-Applied Repellents That Work Best
The EPA registers seven active ingredients for skin-applied mosquito repellents. Not all are equal. Here’s what the evidence shows for the top options:
- DEET: Available in over 500 products and the most extensively tested repellent in history. A 15% concentration protects for about 7 hours against common species. Higher concentrations like 25% to 34% can maintain over 90% protection for up to 12 hours, depending on the mosquito species and conditions. It works against virtually every biting mosquito studied.
- Picaridin: Nearly as effective as DEET and preferred by many people because it’s odorless, non-greasy, and won’t damage plastics or synthetic fabrics. At a 20% concentration, picaridin provides 95% or better protection for 5 to 7 hours against most species. At matched concentrations against common house mosquitoes, 20% picaridin and 33% DEET both delivered 100% protection through 10 hours in one study.
- IR3535: Available in about 45 products. It’s effective but generally provides shorter protection windows than DEET or picaridin at equivalent concentrations.
- Oil of lemon eucalyptus (OLE): The only plant-derived repellent recommended by the CDC for use in areas where mosquitoes carry disease. Its active compound, PMD, has an unusually low evaporation rate for a botanical, which is why it lasts so much longer than other plant oils. A 30% PMD formulation provided roughly 97% protection for 4 hours in a field study in Bolivia, and a 50% formulation gave complete protection for 6 to 7 hours against malaria-carrying species in Tanzania.
Two lesser-known registered ingredients round out the list: catnip oil (4 products) and 2-undecanone (1 product). These have far less research behind them and are harder to find on store shelves.
DEET vs. Picaridin: Choosing Between Them
This is the most common comparison shoppers face, and the honest answer is that both work well. In head-to-head field studies, DEET at higher concentrations (30% and above) tends to hold its protection longer into the 8 to 12 hour range, while picaridin at 20% sometimes drops below 90% protection around the 8 to 10 hour mark. For a backyard barbecue or a two-hour hike, you won’t notice a difference. For all-day exposure in a heavily infested area, a higher-concentration DEET product has a slight edge.
Picaridin’s practical advantages matter, though. It doesn’t dissolve watch faces, sunglasses, or rain jacket coatings the way DEET can. It feels lighter on skin. For everyday use, many dermatologists and entomologists reach for picaridin themselves.
Treated Clothing and Gear
Permethrin is a synthetic compound applied to fabric rather than skin. It kills or disables mosquitoes (and ticks) on contact when they land on treated clothing. Factory-treated garments maintain their repellency for up to 70 washes, which for most people means roughly a year of regular use. In a randomized study of outdoor workers, permethrin-treated uniforms reduced tick bites by 82% over a full year.
You can buy pre-treated shirts, pants, and socks, or spray your own gear with permethrin spray and let it dry before wearing. Permethrin is not meant for direct skin application. The combination of permethrin-treated clothing and a skin-applied repellent on exposed areas is the gold standard for heavy mosquito exposure, used by military personnel and field researchers in tropical regions.
Spatial Repellents for Patios and Yards
Spatial repellents release active ingredients into the air around you rather than onto your skin. Devices like heated mats and clip-on fans use synthetic pyrethroids (metofluthrin, transfluthrin, or allethrin) to create a zone of protection. These compounds irritate and disorient flying insects, deterring them from entering the treated space. Metofluthrin-based devices have shown strong deterrence rates in laboratory settings, repelling 70% to 80% of insects in controlled tests.
Their real-world effectiveness depends heavily on wind. A light breeze scatters the active ingredient and shrinks your protected zone considerably. They work best on a still evening on a screened porch or in a sheltered seating area. In open, windy conditions, don’t rely on them alone.
Why Most Plant-Based Options Fall Short
Many plant essential oils do repel mosquitoes, but the protection evaporates almost as fast as the oil itself. Citronella, geraniol, lemongrass, and similar botanicals are highly volatile, meaning they go from effective to useless within minutes to roughly an hour after application. You’d need to reapply constantly to maintain any meaningful protection.
Citronella candles are a particularly stubborn myth. The amount of citronella oil in a candle is extremely small, and studies show they work no better than plain, unscented candles at reducing mosquito landings. The “mosquito plant” sold at garden centers (a scented geranium marketed under the citronella name) is similarly ineffective. The plant only releases its oils when leaves are crushed, not just by sitting in a pot on your deck.
The important exception is OLE/PMD, described above. Its unusually low evaporation rate sets it apart from every other plant-based option. Just don’t confuse it with lemon eucalyptus essential oil, which is a different product with far less repellent power. The essential oil is not EPA-registered as a repellent. Look specifically for “oil of lemon eucalyptus” or “PMD” on the label.
Ultrasonic Devices Don’t Work
Electronic mosquito repellents that emit high-frequency sound are one of the most thoroughly debunked products in pest control. A Cochrane systematic review evaluated 10 field studies and found zero evidence that these devices reduce mosquito landings. Every single study showed no difference in bite rates with or without the device running. In fact, 12 of 15 individual experiments recorded slightly higher landing rates when the device was turned on. These results held regardless of location, mosquito species, time of day, or mosquito density. There is no scientific basis for purchasing one.
Safety for Children
Most EPA-registered repellents are safe for children with a few age-specific rules. Products containing OLE or PMD should not be used on children under 3 years old. For infants under 2 months, the safest approach is physical barriers like mosquito netting over strollers and carriers rather than any chemical repellent. For older babies and kids, apply repellent to your own hands first, then rub it onto the child’s exposed skin, avoiding hands, eyes, mouth, and any cuts or irritated areas. There is no evidence that lower DEET concentrations are necessary for children. The concentration determines how long it lasts, not how strong it is.
Putting It All Together
For most people in most situations, a 20% picaridin or 25% to 30% DEET product applied to exposed skin will handle the job. If you prefer plant-based options, OLE with at least 30% PMD is the only botanical with real staying power, giving you roughly 4 to 6 hours of solid protection. Pair any skin repellent with permethrin-treated clothing if you’re spending extended time in mosquito-heavy areas, and save spatial repellent devices for calm evenings on the patio. Skip citronella candles, mosquito plants, and ultrasonic gadgets entirely.