Mosquito repellent works by leaving an active chemical film on your skin that disrupts a mosquito’s ability to find, land on, and bite you — it does not kill the insect or form a physical barrier.
For the full breakdown, see our best Body Mosquito Repellent guide.
A mosquito hunting you is running a tracking sequence: it follows carbon dioxide from your breath, then closes in on body heat, moisture, and the lactic acid and other compounds in your sweat. Repellent interferes with that sequence at the detection stage. The mosquito loses the scent trail, veers off, or lands and leaves without biting. Understanding whether mosquito repellent works on your body this way explains why application technique and ingredient choice matter more than how much you spray.
Here’s what’s actually happening, ingredient by ingredient, plus the application mistakes that quietly waste a good product.
What EPA-Approved Ingredients Do Differently
Each registered active ingredient disrupts mosquito host-seeking in a slightly different way, but all of them reduce bites rather than repelling from a distance. DEET, the most studied option, interferes with the olfactory receptors mosquitoes use to detect human sweat compounds — the insect can still smell your breath’s carbon dioxide, so it flies toward you, then fails to lock on for a landing. Newer research suggests DEET also makes human skin unappealing on contact.
Picaridin (called icaridin outside the US) works on the same host-detection pathways with less odor and no damage to plastics or synthetic fabrics. IR3535 is a biopesticide structurally related to the amino acid alanine, and it can irritate eyes, so keep it away from that area. Oil of lemon eucalyptus and its synthesized form, PMD, are plant-derived and EPA-registered; the CDC draws a hard line between these registered products and “pure” lemon eucalyptus essential oil, which lacks validated testing and is not recommended. 2-undecanone, sold under the name methyl nonyl ketone, rounds out the list.
Read the Label Before Anything Else
An EPA registration number — formatted like “123456-1” — is your proof the product was tested for both safety and effectiveness when used as directed. Any repellent worth buying carries one. Concentration and label directions set how long protection lasts; sweating, water exposure, and heat shorten it.
| Active Ingredient | How It Works | Watch Out For |
|---|---|---|
| DEET | Blocks the scent receptors mosquitoes use to find human sweat | Above 50% gives no extra protection |
| Picaridin | Disrupts the same host-detection cues, low odor | Less familiar name, equally effective |
| IR3535 | Biopesticide tied to the amino acid alanine | — |
| Oil of lemon eucalyptus / PMD | Plant-derived, registered version of the repellent compound | Not for children under 3 years |
| 2-undecanone | Also called methyl nonyl ketone | Fewer products on shelves |
| Citronella / catnip oil | Registered or exempt depending on formulation | Check each product’s registration status |
Choosing between these comes down to how long you’ll be outside and how the product feels on your skin — testing several formulations side by side is the only way to know which one carries you through an evening comfortably, and a tested lineup of the best body mosquito repellent takes the guesswork out of that comparison.
Application Mistakes That Waste a Good Repellent
Most failures trace back to technique, not the product. The CDC’s guidance on repellent use comes down to a few rules worth repeating.
- Apply only enough to cover exposed skin — saturating your skin adds risk without adding protection.
- Never spray directly onto your face. Spray onto your hands first, then apply sparingly around your face and ears.
- Skip eyes, mouth, cuts, wounds, and irritated skin entirely.
- Don’t apply repellent under your clothing.
- Apply sunscreen first, then repellent on top.
- Reapply only as the label directs.
- Wash treated skin with soap and water once you’re back indoors, and wash treated clothing before wearing it again.
A common assumption is that a higher concentration equals stronger protection. It doesn’t — anything above 50% DEET performs no better than 50%. The bigger variable is how faithfully you follow the label.
Age Limits and Safety Basics
EPA-registered repellents are considered safe for pregnant and breastfeeding people when used as directed, according to the CDC. The limits worth committing to memory concern young children.
- No insect repellent on babies younger than 2 months.
- No oil of lemon eucalyptus or PMD products on children under 3 years.
- An adult should apply the product to a child — never let a child handle it, and never apply it to a child’s hands.
If a rash or reaction develops, stop using the product, wash it off with mild soap and water, and contact a poison-control center or clinician as needed. EPA’s list of skin-applied repellent ingredients is the definitive reference for what’s registered and safe to use.
Common Questions
Does repellent kill mosquitoes when they land on treated skin?
No. EPA-registered repellents don’t kill mosquitoes. They interfere with the insect’s ability to locate and bite you, which is why bites drop even when mosquitoes stay in the area. Killing the insects is a separate job handled by insecticides, not skin-applied repellent products.
Why do mosquitoes still buzz around me after I apply repellent?
Repellents don’t create an invisible force field. Mosquitoes still detect the carbon dioxide in your breath and fly toward you. What changes is the final approach — the treated skin film keeps many of them from locking on and landing. Some will hover nearby without biting, and that’s expected behavior, not a product failure.
Is natural repellent as effective as DEET?
It depends entirely on whether the product is EPA-registered. Registered options like oil of lemon eucalyptus and its synthesized form, PMD, have proven effectiveness. Pure lemon eucalyptus essential oil sold without registration does not — the CDC specifically advises against relying on it because it lacks validated testing.
Sources
- U.S. Environmental Protection Agency. “Skin-Applied Repellent Ingredients.” Lists EPA-recognized active ingredients and their registered product counts.
- CDC. “Mosquitoes, Ticks, and Other Arthropods.” Supports pregnancy, breastfeeding, and age-related guidance for repellent use.
- CDC. “Mosquitoes: Prevention.” Covers application technique, reapplication, and washing guidance.