Mosquito Bite Prevention: DEET, Picaridin and What Actually Works

Almost every destination guide on this site ends up saying the same thing: use a good repellent and cover up. That's because bite prevention is the one measure that works against nearly every mosquito-borne disease at once — dengue, malaria, Zika, chikungunya, Japanese encephalitis and yellow fever. No single vaccine covers that spread; a bottle of the right repellent and a set of treated clothes come close.

This is the guide the others point to. It covers which active ingredients genuinely work, what concentration to buy, how to use permethrin on clothing, and why the time of day a mosquito bites should shape your routine. It's based on CDC guidance.

First: two products, not one

The approach that studies by the CDC and the US military keep confirming is a two-layer system: a repellent on exposed skin, plus permethrin-treated clothing worn over the top. Used together, this cuts mosquito bites by more than 90% in field conditions — far better than either alone. Almost everyone who returns from the tropics with dengue or malaria was using neither properly (or was relying on a wristband or a citronella candle, which don't work).

So the plan is: skin repellent + treated clothing. Here's how to choose each.

Skin repellents: DEET vs picaridin

The two front-line active ingredients are DEET and picaridin (also called icaridin). Both are recognised by the CDC, and at equal concentrations they offer comparable protection. The difference is mostly in feel and practicality.

DEET has the longest track record, especially against the Anopheles mosquito that spreads malaria. The trade-offs: it can feel oily, has a mild odour, and can damage plastics and some synthetic fabrics and gear. For travellers, the sweet spot is 30–35% — enough for several hours of protection. Going far higher adds little; DEET's protective duration plateaus around 50%.

Picaridin performs as well as DEET at the same strength and is, for many people, nicer to use: it's odourless, non-greasy, and doesn't melt plastics. For tropical travel, use 20% or higher, which gives roughly 8–12 hours of protection and is reapplied every several hours as directed.

The key number to remember either way: avoid products below about 20%. Lower concentrations protect for too short a time to be reliable in a high-risk area.

Other options: IR3535 is gentle and fine for lower-risk destinations but protects for a shorter window. Oil of lemon eucalyptus (OLE/PMD) is the only plant-based repellent the CDC recognises and can match low-concentration DEET — but it must be the refined product (not raw essential oil), and it's not for children under three. Skip citronella candles, ultrasonic apps and repellent wristbands entirely; they don't provide meaningful protection.

Permethrin: for clothing, never skin

Permethrin is the other half of the system, and it works differently — it's an insecticide you apply to fabric, not skin. At a 0.5% concentration it repels and kills mosquitoes, ticks and other biters on contact.

How to use it:

• Treat shirts, trousers, socks, and gear (and mosquito nets) with a permethrin spray, following the bottle directions — or buy factory pre-treated clothing.
• Treat clothing 24–48 hours before you pack so it dries fully.
• Treatment survives several washes (roughly six), so one application covers a typical trip.
• Never apply permethrin to skin — it's for fabric only.

For rural, trekking, safari or jungle travel, permethrin-treated clothing is the foundation your skin repellent sits on top of.

The detail that changes everything: day vs night

Different diseases come from different mosquitoes, and they bite at different times — which means "when" to apply repellent matters as much as "what."

• The Aedes mosquito (dengue, Zika, chikungunya, yellow fever) is a daytime biter, most active around dawn and dusk, and thrives in towns and cities.
• The Anopheles mosquito (malaria) is a night biter, most active from dusk to dawn.

So in a place with both malaria and dengue risk — much of Southeast Asia, sub-Saharan Africa, parts of Latin America — the honest answer is protect yourself around the clock. Repellent during the day for dengue, repellent and a permethrin-treated bed net at night for malaria. Our guides to dengue and malaria prevention go deeper on each.

Using repellent properly

• Apply to all exposed skin, not just a dab on the arms.
• If using sunscreen too, apply sunscreen first, let it absorb, then the repellent on top.
• Reapply as the label directs, and more often if you're sweating heavily or swimming.
• For children, the CDC considers DEET, picaridin and IR3535 suitable from two months of age (used per instructions); keep OLE/PMD for ages three and up.
• Combine with long, loose, light-coloured clothing and screened or air-conditioned rooms where possible.

The bottom line

Bite prevention is the single highest-value habit in travel health, because it works against every mosquito-borne disease at once and needs no prescription. Buy a skin repellent with 20%+ picaridin or 30–35% DEET, treat your clothing with 0.5% permethrin before you go, and apply protection by day for dengue and by night for malaria. Do that consistently and you've removed most of the mosquito-borne risk from your trip in one move.

See what's relevant at your destination on the interactive travel vaccine map, and pair this with our guides to dengue, malaria prevention and specific destinations like Bali, Thailand and an East African safari.

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This guide is general information based on CDC guidance and is not a substitute for personalised medical advice. Always follow product label instructions and consult a travel-health professional for your specific itinerary.