DEET: still good, widely misunderstood
Seventy years of evidence, one persistent myth, and a solvent habit nobody warns you about. The veteran of the repellent aisle deserves an honest profile — so here it is.
DEET was developed for the U.S. Army in 1946 and has been the world's reference repellent since the 1950s. Nothing on the shelf carries more accumulated evidence, and against ticks it plainly works — it anchors Tier 1 of our evidence tiers alongside picaridin and permethrin. The reasons it no longer tops our database have nothing to do with whether it repels, and everything to do with what it's like to live with.
The 100% myth — DEET's plateau
See those last two bars? They're the same height on purpose. Protection time climbs with concentration until roughly 50%, then flatlines — a 98% bottle buys the same window as a 50% one, plus maximum smell, skin load, and melted gear. "Maximum strength" DEET is a duration product marketed as a power product.
Practical takeaway: 20–30% is the DEET sweet spot for tick country, and controlled-release formulas (3M's Ultrathon, at 34%) stretch furthest per point of concentration. Anything above 50% is money spent on the myth.
The solvent problem
DEET's under-reported weakness: it dissolves things. It's chemically aggressive toward many plastics and synthetics — in our testing seasons it clouded sunglass lenses, tackified a watch strap, and left fingerprint-shaped marks on a shell jacket, all via sprayed hands. Cotton and wool don't care; your electronics, eyewear, and technical fabrics do. It's the main reason DEET products sit a step below picaridin on our rubric's experience score despite equal efficacy.
When DEET is still the right call
- Budget. Per protected hour it's the cheapest Tier 1 active, usually by a wide margin.
- Availability. Every pharmacy, gas station, and trailhead shop on earth stocks it — the replaceability champion. (Choosing between DEET and picaridin for a trip abroad? Our sister site runs that exact comparison for travelers: picaridin vs DEET for travel.)
- Track record. If you want the active with seven decades of use behind it, this is it.
Whichever way you go, remember DEET is a skin layer only — the clothing layer is permethrin's job, and the two together are the real system.
Our top-scored DEET products
Scores from our published rubric — full field, including the 98% formulas we don't recommend, in the database.
Free tool See the plateau yourself → Slide through DEET's concentrations in the duration calculator and watch the window stop growing.Common questions
Is 100% DEET better for ticks?
No. Protection time plateaus around 50% — a 98% formula buys the same ~6–8 hour window with maximum downsides. Concentration is a duration dial with a ceiling, not a strength dial.
What percentage should I use?
20–30% for tick country: roughly 4–6 hours at 25%, 4–6+ at 30%, with controlled-release 34% formulas reaching the top of the range. Below 10% the window is too short to trust in the woods.
Does it really damage gear?
Yes — DEET acts as a solvent on many plastics and synthetics. Sunglasses, watch straps, screens, and technical fabrics are the classic casualties. Cotton and wool are fine; apply carefully or switch to picaridin.