DEET at a glance
- Developed
- 1946
- By the U.S. Army, per the EPA
- Common range
- 5 to 99 percent
- Higher lasts longer
- Best tested range
- 25 to 30 percent
- Consumer Reports, 2025
- Protection time
- 2 to 12 hours
- EPA, by concentration and pest
Where did DEET come from?
DEET is short for N,N-diethyl-meta-toluamide. The EPA says the U.S. Army developed it in 1946 and it was registered for use by the general public in 1957. About 120 products containing it are registered with the EPA today, from roughly 30 companies.
The EPA reassessed it in 1998 and again in 2014 and concluded that DEET products used as directed do not present a health concern, including for children.
What does the percentage of DEET mean?
The percentage mainly sets how long a coat lasts. The EPA puts DEET at about two to ten hours against ticks and two to twelve hours against mosquitoes, depending on the concentration, and products run from 5 to 99 percent.
A 98 percent bottle does not stop a bug that a 30 percent bottle lets through. It just means reapplying less often. Consumer Reports found products between 25 and 30 percent performed best in its 2025 ratings, which makes that the sensible range for a day hike.
Why does DEET damage gear?
DEET acts as a solvent on some materials. The University of Florida's extension service warns it will damage plastics, acetate, rayon, spandex, synthetic fabrics other than nylon, leather, watch crystals and painted or varnished surfaces. It does not damage nylon, cotton or wool.
On a hike that means sunglasses, a watch face, a phone case and the stretchy panels in a lot of technical clothing. Wash it off your hands before handling them.
What this means when you're choosing
- 25 to 30 percent DEET for a normal day on the trail
- An EPA registration number on the label
- Ticks as well as mosquitoes on the list of pests
- A pump or wipe if you want to keep it off your gear
DEET vs Picaridin
| DEET | Picaridin | |
|---|---|---|
| Typical strength | 25 to 30 percent | 20 percent |
| Effect on gear | Can damage plastics and most synthetic fabrics | Does not damage plastics or synthetics |
| Feel and smell | Oily at higher strengths, with a chemical smell | Lighter on skin, with little smell |
| Consumer Reports, 2025 | The best 25 to 30 percent products led the ratings | Effective, though not every product matched the best DEET |
Which to pick: Both are on the CDC's list and both work on ticks and mosquitoes. Picaridin is the easier everyday choice around technical gear; DEET is the one Consumer Reports rated highest for the worst bug days.
The common mistake
Buying the highest percentage for the strongest protection
A near-pure DEET bottle lasts longer between coats, but it does not repel anything a 30 percent product misses. It is also oilier and harder on gear. For most hikes, 25 to 30 percent and reapplying at lunch is the better trade.
Common questions
Is DEET safe for kids?
The EPA found no reason to limit DEET by age or concentration for children, based on its 1998 and 2014 assessments. The CDC adds practical rules: an adult applies it, keeping it off a child's hands, eyes and mouth.
Will DEET ruin my rain jacket?
It can damage many synthetic fabrics and coatings, though the University of Florida notes it does not harm nylon. Keep DEET on skin, let it dry before pulling on a shell, and consider picaridin if you wear a lot of technical clothing.
Where this is defined
- DEET, U.S. Environmental Protection Agency
- ENY-260/IG122: Use and Application of Insect Repellents, University of Florida IFAS Extension
- DEET Fact Sheet, National Pesticide Information Center