The most effective personal mosquito repellents use one of four EPA-registered active ingredients: DEET, picaridin, oil of lemon eucalyptus (OLE), and IR3535. At the right concentrations, these ingredients can keep mosquitoes away for anywhere from two to twelve hours per application. Which one you choose depends on how long you need protection, where you’re headed, and who’s wearing it.
How the Four Main Ingredients Compare
DEET has been the standard since the 1950s and remains the most widely tested repellent on the market. Products range from less than 10% to over 30% concentration. A 10% DEET product protects for roughly two hours. A 24% concentration averages about five hours. Beyond 20 to 30%, you get diminishing returns: higher concentrations extend duration somewhat, but the gains shrink. A well-formulated 20% DEET lotion with controlled-release technology can match the protection of a 50% DEET spray in alcohol, and a 34% DEET lotion has been shown to provide up to 12 hours of protection. So concentration matters, but formulation matters just as much.
Picaridin is the closest alternative to DEET in both effectiveness and duration. At 20% concentration, it provides 8 to 12 hours of protection. Even a 5% picaridin product covers you for 3 to 4 hours. It has no strong smell and doesn’t dissolve plastics the way DEET can, which makes it popular with people who dislike the feel or odor of traditional repellents.
Oil of lemon eucalyptus (sold as its refined compound, PMD) is the strongest plant-derived option. A 20% PMD product performs on par with 20% DEET in both lab and field studies, lasting 6 to 8 hours. The 10% formulation is notably weaker. One important distinction: refined OLE registered with the EPA is not the same as “pure” oil of lemon eucalyptus you might find in a health food store. Those unrefined products haven’t been tested or registered as insect repellents.
IR3535 is common in products from brands like Avon. At 20% concentration, it matches 20% DEET in lab testing. But lower concentrations fall off fast. A 7.5% IR3535 product provided only 10 to 60 minutes of protection in one study and about two hours in others. If you go with IR3535, look for the higher concentration formulas.
Choosing a Concentration for Your Situation
If you’re spending an hour or two in your backyard on a summer evening, a lower-concentration product (5 to 10% DEET or picaridin) is perfectly adequate. For a full day of hiking, camping, or travel in an area with heavy mosquito activity, step up to 20% or higher. In regions where mosquitoes carry diseases like malaria, dengue, or Zika, this is especially important.
Higher concentration doesn’t mean stronger repellency at any given moment. It means the protection lasts longer before you need to reapply. A 30% DEET spray doesn’t create a bigger “force field” than a 10% spray. It just keeps working for more hours.
Treating Clothing With Permethrin
Permethrin is a separate tool that works alongside skin-applied repellents. You spray it onto clothing, gear, or shoes, let it dry completely outdoors, and the treatment kills or repels mosquitoes (and ticks) on contact with the fabric. It binds tightly to fibers and survives multiple washes with minimal loss when applied correctly.
A few rules to follow: never apply permethrin directly to skin, never spray it onto clothes while you’re wearing them, and always apply it in a well-ventilated outdoor area protected from wind. Wash treated clothing separately from the rest of your laundry. Don’t over-treat items. Products made specifically for fabric treatment include application instructions, and using more than directed doesn’t improve protection.
Combining permethrin-treated clothing with a skin repellent gives you the most complete personal protection available. The treated fabric handles mosquitoes that land on your clothes, while the topical repellent covers exposed skin.
Safety for Children and Infants
Both the American Academy of Pediatrics and the CDC recommend using EPA-registered repellents on children. DEET can be used on infants over two months old, though parents should apply it sparingly, and the maximum recommended concentration for children is 30%. For newborns and premature infants, extra caution is warranted.
Oil of lemon eucalyptus and PMD products should not be used on children younger than 3 years old. Picaridin and IR3535 don’t carry specific pediatric age restrictions beyond standard guidance for infants, making them reasonable alternatives for young children. DEET occasionally causes skin rashes, particularly at higher concentrations, but this is rare. Apply repellent to your own hands first, then rub it onto the child’s skin, avoiding their hands, eyes, and mouth.
Using Repellent With Sunscreen
If you need both sun protection and mosquito protection, apply sunscreen first. Wait about 20 minutes for it to absorb into your skin, then apply your repellent on top. This layering order lets each product do its job.
One complication: DEET-based repellents can reduce sunscreen effectiveness by about 40%. That means you’ll likely need to reapply sunscreen more often than usual. Switching to a higher SPF doesn’t solve the problem, since SPF 30 already blocks 97% of UV rays and SPF 50 only adds another percentage point. More frequent reapplication is the better strategy.
Avoid combination products that package sunscreen and repellent together. Sunscreen needs reapplication every couple of hours, while repellent lasts much longer. Reapplying a combo product to maintain sun protection means layering on more repellent chemicals than necessary.
Do Spatial Devices and Candles Work?
Clip-on devices, candles, and other “spatial” repellents release active ingredients into the surrounding air rather than onto your skin. Citronella candles are the most familiar example. In controlled studies, citronella candles reduced mosquito bites by about 42% compared to unscented candles. Some essential oil candles using blends of geraniol, cinnamon, or rosemary reached a 40 to 56% reduction in mosquito attraction.
Those numbers sound decent until you compare them to topical repellents, which block close to 100% of bites when applied correctly. Spatial devices can take the edge off in a contained outdoor area like a patio, but they’re not a substitute for a skin-applied repellent when mosquitoes are thick or when disease risk is a concern. Wind, open spaces, and movement all reduce their effectiveness further.
Getting the Most From Any Repellent
Apply repellent to all exposed skin, not just your arms. Mosquitoes will find any unprotected patch, and ankles, necks, and the backs of hands are common bite sites people miss. Spray products onto your hands first before rubbing them onto your face rather than spraying your face directly.
Reapply based on the product’s labeled duration, not on a fixed schedule. Sweating, swimming, and toweling off remove repellent faster than normal wear. If you start getting bitten before the expected duration is up, reapply. When you come indoors for the day, wash treated skin with soap and water.