An EPA-registered repellent with DEET or picaridin works best outdoors, and 20–30% DEET typically protects for hours without needing the strongest concentration.
Not every product on the shelf earns its place in your pack. The CDC recommends EPA-registered repellents containing DEET, picaridin, IR3535, oil of lemon eucalyptus, para-menthane-diol, or 2-undecanone — and the EPA’s own guidance says concentration matters more than brand. Below, what the evidence actually supports, how to apply it correctly, and the mistakes that shorten protection.
Which Ingredients Actually Keep Mosquitoes Off?
DEET has the longest track record, but picaridin and IR3535 are equally credible options, and oil of lemon eucalyptus fills a third slot for people avoiding synthetics.
- DEET. The most established option.
- Picaridin. CDC-recommended and EPA-registered, sold as KBR 3023 in the U.S. and icaridin abroad.
- IR3535. A CDC-recommended synthetic. The chemical name is 3-[N-Butyl-N-acetyl]-aminopropionic acid, ethyl ester, and it appears in registered products under the label IR3535.
- Oil of lemon eucalyptus (OLE) and PMD. Effective only when the product carries the EPA-recognized active ingredient — not when it’s plain lemon-eucalyptus essential oil. Not for children under 3.
- 2-undecanone. Included among CDC’s recommended EPA-registered actives, though it appears in fewer products.
Citronella and other plant oils have some EPA-registered versions, but the CDC and EPA prioritize the named actives above. Products without EPA registration haven’t been reviewed for effectiveness.
Does a Higher Percentage Mean Longer Protection?
Up to a point. Protection rises with concentration, then flattens: DEET above roughly 50% doesn’t add protection time, and products below 10% may last only one to two hours.
| Active Ingredient | Typical Range | Practical Read |
|---|---|---|
| DEET | 10–30%+ | 20–30% is the sweet spot for long outings |
| Picaridin | 5–20% | Low odor, good all-day option |
| IR3535 | 10–20% | Well-tolerated synthetic alternative |
| OLE / PMD | 10–30% | Plant-derived; works only with EPA-active OLE |
| 2-undecanone | 7–20% | Effective but less widely stocked |
| Citronella / plant oils | Varies | Shorter, less reliable; check EPA registration |
Real-world duration also depends on mosquito species, heat, sweating, water exposure, and rubbing against gear or clothing. Sweating heavily, swimming, or wiping your arms shortens any product’s window, so reapply according to the label.
What Does Correct Application Look Like?
The label is the instruction manual — EPA registration means the product has been reviewed for safety and effectiveness when used as directed. Follow it exactly.
- Apply only enough to cover exposed skin or clothing, and never under clothing.
- Keep it off cuts, wounds, and irritated skin.
- Never spray directly on the face — spray onto hands first, then apply sparingly around the face and ears, avoiding eyes and mouth.
- Adults should apply repellent to children; kids shouldn’t handle the product themselves.
- After coming inside, wash treated skin with soap and water and launder treated clothing before wearing it again unless the label says otherwise.
If a rash or reaction appears, stop use, wash with mild soap and water, and call poison control or a medical professional if symptoms persist. EPA-registered repellents are considered safe for pregnant and breastfeeding people when used per label instructions.
What Else Cuts Mosquito Bites Outdoors?
Repellent handles exposed skin, but barriers and habits shrink the number of bites before you ever reach for the spray.
Long sleeves, long pants, and socks reduce exposed skin, and clothing treated with 0.5% permethrin adds a layer of protection — pair it with a skin repellent rather than relying on it alone. Skip outdoor time when mosquitoes are most active, use screens or air conditioning at home, and clear standing water around the house. If you’re comparing bottles for a humid climate, this tested roundup of mosquito repellent for Florida conditions is a practical next step after you pick a concentration.
One note on “natural” claims: unregistered plant-based products may contain ingredients the EPA hasn’t evaluated for effectiveness, and pure lemon-eucalyptus essential oil is not the same as EPA-registered OLE. When in doubt, check the ingredient list against the EPA’s repellent-finder page.
Common Questions
Is DEET safe for kids?
Yes, when used per label instructions. Adults should apply repellent to children rather than letting kids handle the bottle, and products should be kept off hands that may end up near the mouth. Oil of lemon eucalyptus is the exception for younger kids: it isn’t for children under 3 years old.
Can I use sunscreen and repellent together?
Apply sunscreen first, let it absorb, then apply repellent over it. Choose products separately rather than relying on combination formulas — sunscreen needs frequent reapplication, while repellent should only be reapplied according to its label. Washing both off with soap and water after returning indoors is the simplest routine.
Does a higher DEET percentage protect longer than 50%?
No. Protection time rises with concentration up to roughly 50%, then plateaus, so a 90% product doesn’t last meaningfully longer than a 30% one. For most outdoor situations, a 20–30% DEET product or a mid-range picaridin product is the practical pick, with reapplication driven by sweat, water, and abrasion.
Sources
- U.S. Environmental Protection Agency. “Find the Repellent That Is Right for You” Supports EPA-registered active ingredients and concentration guidance.
- U.S. Environmental Protection Agency. “Skin-Applied Repellent Ingredients” Supports DEET, picaridin, IR3535, OLE/PMD, and 2-undecanone details.
- Centers for Disease Control and Prevention. “Mosquitoes: Prevention” Supports CDC-recommended actives and outdoor prevention tactics.