Mozzwise Guides

DEET — The Gold Standard

DEET (N,N-Diethyl-meta-toluamide) has been protecting people from mosquito bites since the 1950s and remains the most studied repellent on the planet. At concentrations of 20-30%, it provides 6-8 hours of reliable protection against virtually all mosquito species, including the Anopheles mosquitoes that transmit malaria.

Higher concentrations do not repel better — they just last longer. A 30% DEET product is the sweet spot for most tropical travel. The downsides are real but manageable: it has a strong chemical smell, it can damage plastics and synthetic fabrics, and some people find it greasy on the skin. For high-stakes destinations — malaria zones, dense jungle, extended outdoor exposure — DEET is still the repellent most recommended by the WHO and CDC.

One common misconception: DEET is not dangerous at recommended concentrations. Decades of safety data support its use on adults and children over two months of age. Apply it to exposed skin (not under clothing), avoid the eyes and mouth, and wash it off when you come indoors.

Picaridin — The Modern Alternative

Picaridin (also called Icaridin or KBR 3023) was developed by Bayer in the 1990s and has been gaining ground on DEET ever since. At 20% concentration, it matches DEET for duration and effectiveness against most mosquito species, including Aedes aegypti (the dengue and Zika vector) and Anopheles species.

The practical advantages are significant for travelers: Picaridin is nearly odorless, does not damage plastics or fabrics, feels lighter on the skin, and does not leave that distinctive chemical residue. If you have ever had DEET melt a watch strap or ruin a rain jacket, Picaridin solves those problems entirely.

The WHO has endorsed Picaridin for use in malaria-endemic areas, and the CDC lists it alongside DEET as a recommended active ingredient. For city travel, resort stays, and family trips where comfort matters as much as protection, Picaridin is often the better choice. The one caveat: at lower concentrations (5-10%), it does not last as long as equivalent DEET formulations, so look for 20% products.

Oil of Lemon Eucalyptus (OLE) — The Natural Option

Oil of Lemon Eucalyptus is the only plant-based repellent recognized by the CDC as effective against mosquitoes. Its active compound, PMD (para-menthane-3,8-diol), provides roughly 2-4 hours of protection at 30% concentration — shorter than DEET or Picaridin, but meaningful for low-to-moderate risk situations.

OLE works well for evening walks in European cities, daytime sightseeing in Southeast Asian towns, or anywhere mosquitoes are a nuisance rather than a serious disease vector. It has a pleasant eucalyptus scent that many people prefer to chemical alternatives. The important limitation: OLE should not be used on children under three years old, and it needs to be reapplied more frequently than synthetic options.

Do not confuse Oil of Lemon Eucalyptus (the refined repellent) with pure lemon eucalyptus essential oil — they are different products with very different effectiveness. The essential oil alone has not been proven to repel mosquitoes reliably.

IR3535 — The European Favorite

IR3535 (Ethyl butylacetylaminopropionate) has been used in Europe for over 20 years and is the active ingredient in many Avon and Merck repellent products. It offers moderate protection — roughly 4-6 hours against most mosquito species at 20% concentration.

IR3535 has an excellent safety profile, which is why it appears in many family-oriented products. It is less effective than DEET or Picaridin in head-to-head studies against Anopheles mosquitoes, so it is not the first choice for malaria zones. But for destinations where dengue-carrying Aedes mosquitoes are the primary concern, or for travelers who want something gentler than DEET, IR3535 is a solid middle-ground option.

One practical note: IR3535 can damage certain plastics and synthetic materials, similar to DEET, so be mindful when applying near sunglasses or tech gear.

Which Repellent for Which Trip

The decision tree is simpler than it looks. For malaria zones (Sub-Saharan Africa, parts of South and Southeast Asia, Amazonia), use DEET 20-30% or Picaridin 20% — these are non-negotiable situations where maximum protection matters. For dengue and Zika hotspots (urban Southeast Asia, Central America, the Caribbean), either DEET or Picaridin works well, with Picaridin often preferred for the comfort factor during long city days.

For European summers, Mediterranean holidays, or low-risk destinations where mosquitoes are a nuisance but not a disease threat, OLE or IR3535 is perfectly adequate. If you are traveling with children, Picaridin is usually the best all-around choice — effective, odorless, and fabric-safe.

One strategy experienced travelers use: pack Picaridin as your daily repellent and keep a small DEET product for high-exposure moments like dawn hikes or evening game drives. Layering repellent with permethrin-treated clothing (see our permethrin guide) gives you the strongest possible protection without dousing yourself in chemicals.

This guide is for informational purposes only and is not medical advice. Product recommendations include affiliate links. Consult a travel health professional before your trip.