Is DEET safe for humans?

Yes. DEET has been used by over 200 million people annually since 1946 and is registered by the EPA. The EPA's 1998 re-registration review found no risks of concern when used as directed. Serious adverse effects are exceedingly rare and usually tied to misuse (ingestion, excessive application). The CDC and EPA both recommend it as a first-line repellent.

What concentration of DEET should I use?

For most people, 20–30% DEET is the sweet spot: it provides 5–8 hours of protection against mosquitoes and ticks without over-exposure. 10% lasts about 2 hours (fine for a backyard evening). Above 50%, efficacy plateaus but side-effect risk climbs — only use 50%+ in true wilderness expeditions with no resupply.

How long does DEET last?

Duration scales with concentration up to about 50%. 10% DEET lasts roughly 2 hours; 20–25% lasts 5–6 hours; 30–35% lasts 6–8 hours; 50% lasts up to 12 hours. 98% DEET doesn't last significantly longer than 50% — the extra concentration extends duration marginally but not proportionally.

Can children use DEET?

Yes, with precautions. The AAP says DEET up to 30% is safe for children over 2 months of age. Do not use DEET on infants under 2 months. Apply to your own hands first and then onto the child, avoiding the hands, eyes, and mouth. Choose the lowest concentration that gives adequate protection for your outing.

Can you use DEET during pregnancy?

Current evidence suggests DEET is safe during pregnancy when used as directed. The CDC recommends its use for pregnant women traveling to malaria or Zika zones, where the disease risk far outweighs any theoretical chemical risk. A 2014 study of 449 pregnant women found no adverse birth outcomes. Always apply to exposed skin only and wash off after returning indoors.

Does DEET damage fabrics or plastics?

Yes. DEET dissolves or damages many synthetic fabrics (nylon, polyester, spandex), plastics, watch faces, sunglasses, and synthetic-fiber clothing. Apply only to exposed skin. Gear-conscious users (hikers, backpackers with expensive equipment) often prefer picaridin, which is completely material-safe.

Does DEET reduce sunscreen effectiveness?

Yes. Studies show DEET reduces SPF by approximately 33% when applied over chemical sunscreen. Apply sunscreen first, let it fully absorb (5–10 minutes), then apply DEET on top. Compensate by using a higher SPF sunscreen (SPF 30–50) when combining the two products. Picaridin and IR3535 do not reduce SPF.

What bugs does DEET repel?

DEET is broad-spectrum: it repels mosquitoes (all species, including dengue/Zika Aedes and malaria Anopheles), ticks (including Lyme-carrying Ixodes), biting flies, gnats, chiggers, no-see-ums, and fleas. It is the most broadly effective topical repellent available and the benchmark against which all others are tested.

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Gold Standard Repellent

The complete DEET guide

How it works, what the EPA and CDC safety data actually say, which concentration to choose, who should avoid it, and how long each strength really lasts.

EPA-registered since 1957 10%→2 hrs · 30%→8 hrs Safe for children 2 mo+ CDC recommended

The Science

How DEET actually keeps bugs off

DEET (N,N-diethyl-meta-toluamide) was developed by the US Army in 1946 after WWII jungle warfare experience. For decades scientists assumed it worked by odor masking — new research reveals it's more sophisticated than that.

Blocks insect olfaction

DEET activates olfactory receptors that detect it as a strong, aversive stimulus. Insects actively avoid DEET-treated skin rather than simply failing to find it. A 2008 Science study identified OR83b receptors in Drosophila as a key mechanism.

Vapor barrier effect

DEET evaporates slowly from skin, creating a vapor concentration gradient that triggers avoidance behavior before insects get close enough to smell lactic acid or CO₂ from the host. Higher concentrations extend this vapor envelope's duration.

Broad-spectrum coverage

DEET works on all major biting species: Aedes (dengue, Zika), Anopheles (malaria), Culex (West Nile), Ixodes ticks (Lyme), biting flies, gnats, fleas, and chiggers. No other topical matches this breadth.

77+ year track record

More than 200 million people use DEET-based products each year. In over 77 years of use, serious adverse events have been vanishingly rare — mostly involving chronic misuse (ingestion, application to damaged skin, excessive frequency) rather than normal use.

Concentration Guide

10% vs 25% vs 98% — which do you need?

Duration scales with concentration up to about 50%, where efficacy plateaus. Choose the lowest concentration that covers your activity window — more isn't better, just longer-lasting.

Concentration	Duration	Best for	Notes
5–10%	~2 hours	Backyard · Evening	Good for a patio dinner or short walk. Reapply if you stay out longer. Many children's formulations use this range.
20%	~4–5 hours	Day hike · Camping	Solid protection for an afternoon outing. Apply once; reapply if you sweat heavily or go in water.
25–30%	~6–8 hours	Full-day outdoors · Tick country	The practical sweet spot for most adults. Covers a full-day hike with one application. Also the AAP-approved ceiling for children.
40–50%	~10–12 hours	Malaria zones · Multi-day treks	Strong option for high-risk travel with limited resupply. Efficacy plateaus near 50% — higher concentrations add minutes, not hours.
98–100%	~10–12 hours	Extreme expeditions only	Negligibly longer than 50% in field studies. High solvent concentration; significant plastic/fabric damage risk. Only justified for dense jungle or Arctic/tundra with no resupply options.

Duration estimates based on New England Journal of Medicine field-study data (Fradin & Day, 2002) and EPA registration data. Sweating and water exposure reduce duration significantly.

EPA & CDC Safety Evidence

What the research actually shows

DEET has one of the most thoroughly reviewed safety profiles of any consumer product. The EPA conducted a comprehensive re-registration review in 1998 and found no risks of concern when used as directed.

Strong safety record

EPA 1998 re-registration: "no unacceptable risk to humans or the environment"
WHO Pesticide Evaluation Scheme concludes DEET is safe at registered concentrations
2014 Pregnancy study (449 women, 2nd/3rd trimester): no adverse birth outcomes
CDC recommends for pregnant and breastfeeding women in endemic zones
AAP: safe for children over 2 months at ≤30% concentration

Skin absorption is low

Studies show only 5–17% of applied DEET is absorbed through intact skin. What is absorbed is rapidly metabolized and excreted within 24 hours. No bioaccumulation has been observed in long-term studies. Apply a thin, even layer — no need to saturate the skin.

Rare neurological cases

A small number of neurological adverse events (seizures, encephalopathy) have been reported — almost exclusively in children with repeat excessive application to large areas, or with ingestion. At labeled concentrations and normal use, this risk is not considered significant by EPA or CDC.

Material damage

DEET is an effective solvent and will dissolve or damage rayon, spandex, acetate, leather, vinyl, watch crystals, plastic frames and coated surfaces. Apply only to exposed skin. Gear-heavy users should consider picaridin as a material-safe alternative.

Who Should Be Cautious

Situations requiring extra care with DEET

DEET is appropriate for most people, but a few groups need modified use or should consider alternatives.

Infants under 2 months

No topical repellents — including DEET — should be used on infants under 2 months of age. Use mosquito netting over strollers and carriers instead. After 2 months, picaridin or low-concentration DEET (≤30%) is the AAP-approved approach.

Sensitive skin or eczema

DEET can cause skin irritation, especially at high concentrations on compromised skin. Those with eczema, rosacea, or contact dermatitis may find picaridin (which has a gentler skin profile) more comfortable. Test a small area first if unsure.

Gear-intensive activities

Photographers, watch collectors, hikers with expensive nylon packs, and anyone using synthetic-fabric performance gear should use picaridin instead. DEET will damage plastics, optical coatings, spandex, and many synthetic fabrics on contact.

Highly aerobic activity (running, cycling)

DEET can sting eyes when you sweat. Runners and cyclists often prefer picaridin, which is odorless, non-stinging, and has a dry skin feel. If you use DEET, stick to below-the-neck application during high-sweat activities.

Application

How to apply DEET correctly

Most DEET failures are application errors, not product failures. A thin, complete cover is more effective than thick patches.

Sunscreen first, DEET second

Apply sunscreen, let it absorb for 5–10 minutes, then apply DEET on top. DEET reduces SPF by ~33% — compensate by using SPF 30–50 sunscreen. Picaridin and IR3535 do not affect sunscreen SPF.

Hands-first for faces & kids

Never spray directly at the face. Spray or pump into your palms, then apply, avoiding eyes and mouth. For children, apply to your own hands first, then smooth onto the child — never let children handle repellent themselves.

Reapply only when needed

Unlike sunscreen, DEET doesn't need reapplication on a fixed timer. Reapply when biting resumes — this avoids excess exposure. Sweating, swimming, and rain all reduce duration, so reapply sooner in wet or high-activity conditions.

Wash off after returning indoors

Wash treated skin with soap and water once you're back inside. This is good practice recommended by the EPA, especially for children. There's no need to rush — DEET is safe for the duration of typical outdoor activities.

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BugClear is reader-supported. Product links use affiliate tag credehkr-20 — if you buy through them we may earn a commission at no extra cost to you. Recommendations are based on EPA registration, independent testing, and published field studies.

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