The most effective tick and mosquito repellents use one of four active ingredients recommended by the CDC: DEET, picaridin, IR3535, or oil of lemon eucalyptus (OLE). Each works well when used at the right concentration, and combining a skin repellent with permethrin-treated clothing gives you the strongest protection available against both insects.
The Four Recommended Active Ingredients
All four CDC-recommended ingredients are registered with the EPA, meaning they’ve been evaluated for both safety and effectiveness. They differ mainly in feel, smell, and how long they last on your skin.
DEET has the longest track record and remains the benchmark. The CDC recommends concentrations of 20% or higher for meaningful protection. Going above 50% doesn’t add any extra benefit, so there’s no reason to seek out maximum-strength formulas. Products with less than 10% DEET may only protect you for one to two hours.
Picaridin is a popular alternative because it’s nearly odorless, doesn’t feel greasy, and won’t damage plastics or synthetic fabrics the way DEET can. At 20% concentration, it provides protection comparable to DEET at similar levels.
IR3535 is widely used in Europe and available in the U.S. in several spray and lotion formulas. It’s effective against both mosquitoes and ticks, though it’s less commonly found on store shelves than DEET or picaridin.
Oil of lemon eucalyptus (OLE), sometimes listed as its chemical name PMD, is the one plant-derived option the CDC recommends. Its duration of protection is roughly comparable to 10% DEET, so you’ll need to reapply more frequently than with higher-concentration synthetic repellents.
How Repellents Actually Work
These ingredients don’t poison or kill insects. Instead, they interfere with the smell receptors mosquitoes and ticks use to find you. Your body constantly releases carbon dioxide, body heat, and skin odors that act as homing signals for biting insects. Repellents scramble that signal.
DEET works through multiple pathways. It can directly activate certain mosquito odor receptors (essentially overloading them with a false signal) while simultaneously blocking the receptors that detect human skin odors. Picaridin and IR3535 take a slightly different approach, strongly inhibiting the odor-sensing receptors without activating them first. The net result is the same: the insect can’t locate you through its normal chemical-sensing process. Research published in PLOS ONE confirmed that these repellents target the odor-specific parts of mosquito receptors rather than a shared co-receptor, which helps explain why they’re effective across different insect species, including ticks.
Permethrin for Clothing and Gear
Permethrin is a separate category entirely. You never apply it to your skin. Instead, you spray it on clothing, shoes, backpacks, and gear, where it binds to fabric fibers and kills ticks and mosquitoes on contact by disrupting their nervous systems and causing paralysis. It’s remarkably targeted: permethrin is roughly 2,250 times more toxic to ticks than to humans.
Durability depends on how the clothing is treated. If you buy pre-treated clothing or send garments to a professional treatment service, the protection lasts through about 70 washes. If you spray clothing yourself with a store-bought permethrin product, expect it to hold up for about six washes or six weeks, whichever comes first.
A few safety rules matter here. Always spray garments while they’re off your body, and let them dry completely before wearing. Keep wet permethrin away from cats, because they lack a liver enzyme needed to break it down and can become seriously ill from exposure. Wash permethrin-treated clothing separately from untreated items.
The strongest personal protection strategy is layering: permethrin on your clothes to kill insects on contact, plus a skin repellent on any exposed areas to keep them from landing in the first place.
Applying Repellent Correctly
How you apply repellent matters as much as which one you choose. A few practical details make a real difference in how well it works.
Apply repellent to exposed skin only. Don’t put it under your clothing, and don’t saturate your skin. A light, even coating is enough. If you’re also wearing sunscreen, put the sunscreen on first and let it absorb for about 30 minutes before applying repellent on top. This order matters because repellent needs to sit on the skin’s surface to work, while sunscreen needs to absorb.
Avoid combination sunscreen-repellent products when possible. Sunscreen needs reapplication every two hours (more often if you’re sweating or swimming), but repellent doesn’t need to be reapplied nearly as often. If you do start with a combination product, reapply with sunscreen-only for subsequent applications so you’re not overloading your skin with repellent.
When you come back indoors, wash repellent-treated skin with soap and water. There’s no benefit to leaving it on once you’re no longer exposed to insects.
Using Repellents on Children
Children can safely use DEET-based repellents, but with specific limits. Babies younger than two months should not have any DEET applied to their skin. For infants over two months and all children, the maximum recommended concentration is 30%. Oil of lemon eucalyptus products are not recommended for children under three years old.
Adults should always handle application for young children. Squeeze repellent onto your own hands first, then spread it on the child’s exposed skin, avoiding the hands, eyes, mouth, and using it sparingly around the ears. Children shouldn’t apply repellent themselves, and they shouldn’t handle the container. For babies too young for repellent, mosquito netting over strollers and carriers is the safest alternative.
Choosing Between Products
Your choice depends mostly on how long you’ll be outside and what kind of activity you’re doing. For a two-hour evening walk, a 20% picaridin spray gives solid protection without the sticky feel of DEET. For an all-day hike in tick-heavy woods, 25% to 30% DEET on your skin combined with permethrin-treated pants, socks, and shoes is the most reliable setup.
If you prefer plant-based options, OLE is the only one the CDC stands behind. Other botanical repellents (citronella, lemongrass, cedar oil) are available but generally provide shorter and less reliable protection. They haven’t met the same EPA registration standards as the four recommended ingredients.
Repellent form (spray, lotion, wipe) doesn’t change effectiveness much. Lotions give you more control over where the product goes and tend to last slightly longer since you’re applying a more even layer. Sprays cover large areas quickly but can be wasteful outdoors in wind. Wipes are useful for targeted application on children’s faces and ears.