What is DEET?
DEET is the active ingredient in most conventional insect repellents — a synthetic compound that keeps mosquitoes, ticks, and biting flies from landing on and biting you. It has been the benchmark repellent for more than 60 years, and both Health Canada and the U.S. Centers for Disease Control and Prevention (CDC) list it among the ingredients proven to work. Importantly, DEET does not kill insects. It confuses the sensors mosquitoes and ticks use to detect the carbon dioxide, heat, and skin compounds that reveal a nearby host, so they effectively cannot find you.
In Canada, DEET is one of a small handful of repellent actives that Health Canada has reviewed and registered as both safe and effective when used as directed. The others include picaridin (icaridin) and oil of lemon eucalyptus. If you want a side-by-side of the two most popular options, our picaridin vs DEET comparison breaks down which one wins for different Canadian activities.
What does DEET stand for?
DEET stands for N,N-diethyl-meta-toluamide — sometimes written N,N-diethyl-3-methylbenzamide. It is simply the abbreviation of a long chemical name, not an acronym for anything descriptive. The compound was developed by the U.S. Army in 1946 to protect soldiers in insect-heavy regions and was released for civilian use in 1957. That long track record is a big reason toxicologists regard it as one of the most thoroughly studied repellents available.
What is DEET made of?
DEET is a single man-made organic molecule — N,N-diethyl-meta-toluamide — produced by combining meta-toluic acid with diethylamine. On its own it is a nearly colourless, slightly oily liquid. What you actually buy in a store is that molecule dissolved into a carrier at a labelled strength: an alcohol or water base for sprays, or a gel or lotion base for creams, typically at 5% to 30% DEET in Canada. The rest of the bottle is carrier and, in aerosols, propellant. There is nothing exotic hiding in it — the safety questions all come down to the DEET concentration and how you apply it.
Is DEET bad for you?
For nearly everyone, DEET is not bad for you when you follow the label. Decades of use by hundreds of millions of people, plus repeated safety reviews by Health Canada and the U.S. EPA, have not turned up evidence that ordinary repellent use causes lasting harm. The problems that do get reported are overwhelmingly linked to misuse: swallowing it, getting it in the eyes, applying heavy amounts under clothing, or using adult-strength product on babies. A small number of people experience skin irritation, which is a reason to patch-test and to choose a lower concentration.
It is also worth weighing the other side of the ledger. In Ontario, the realistic day-to-day danger is the bite DEET prevents. Mosquitoes here can carry West Nile virus, and blacklegged ticks can transmit Lyme disease — both tracked by Public Health Ontario and the Public Health Agency of Canada (PHAC). Used sensibly, a proven repellent lowers a real risk.
Does DEET cause cancer?
There is no established link between DEET and cancer. The U.S. Environmental Protection Agency classifies DEET as “not classifiable as to human carcinogenicity,” which is regulator language meaning the available evidence does not show it causes cancer. Health Canada, which re-evaluated DEET and keeps it registered for sale, and the CDC, which actively recommends it, have not flagged a cancer risk from normal use. The alarming posts that circulate online linking bug spray to cancer are not backed by the toxicology these agencies reviewed. If you ever have a specific health concern, the right move is to raise it with your own healthcare provider rather than rely on social media.
Why is DEET banned?
DEET is not banned in Canada — this is one of the most persistent myths about it. It is fully registered by Health Canada and sold across the country in pharmacies, hardware stores, grocery chains, and outdoor retailers. What can look like a “ban” is actually a concentration cap: Health Canada limits consumer DEET to 30% for adults and 10% for children aged 2 to 12, and it phased out the old ultra-high-concentration products (once sold at up to 95–100%) because they added exposure without adding meaningful protection. A handful of individual parks or specialty products elsewhere restrict DEET, but as a rule it remains legal and recommended throughout Canada and the United States.
Is DEET safe for dogs and pets?
No — do not put DEET, or any human bug spray, on your dog, cat, or other pets. These products are formulated and approved for human skin only. A pet will lick treated fur and swallow the repellent, which can cause drooling, vomiting, tremors, or more serious effects depending on the amount. If your animal needs protection from mosquitoes, fleas, or ticks, use a product designed for pets and cleared by your veterinarian. It is also good practice to let repellent dry on your own skin before letting a pet nuzzle you.
Is DEET safe during pregnancy?
Health authorities generally consider DEET acceptable during pregnancy and while breastfeeding when it is used as directed, and studies to date have not found harm to the baby. Because mosquito-borne infections can be especially serious in pregnancy, the CDC specifically advises pregnant people in areas with mosquito-borne disease to use an approved repellent, and DEET is on that list. Apply it only to exposed skin, follow the label, and wash it off indoors. This is general information rather than personal medical advice — talk with your own doctor, midwife, or pharmacist about what is right for you.
Does DEET expire?
DEET the molecule is chemically stable and does not break down easily, so it has a very long shelf life. What actually ages is the product built around it. Aerosol propellant can lose pressure over the years, alcohol carriers slowly evaporate if the cap is not tight, and lotions can separate into layers. Manufacturers usually recommend replacing a bottle after a few years or by any printed date. If your spray has separated, smells off, or no longer sprays a fine even mist, replace it — uneven coverage leaves gaps where mosquitoes and ticks get through.
What does DEET-free mean?
“DEET-free” on a label means only one thing: the product contains no N,N-diethyl-meta-toluamide. It is a marketing statement about what is absent, not a promise that the product is safer or works better. DEET-free repellents rely on a different active ingredient — most commonly picaridin (icaridin), oil of lemon eucalyptus (PMD), or a blend of plant oils. Picaridin is the strongest DEET-free option and matches DEET for mosquito and tick protection with less odour and no damage to plastics or synthetic fabric. Some plant-oil sprays, by contrast, protect for only a short time. The takeaway: read the active ingredient and its concentration, not just the “DEET-free” badge. If you want to go the plant-based route, see what actually holds up in our natural mosquito repellent guide for Ontario.
DEET Myths vs Facts
| Claim you hear | What the authorities say |
|---|---|
| “DEET causes cancer” | No established link (U.S. EPA: “not classifiable”; Health Canada & CDC: no cancer risk from normal use) |
| “DEET is banned in Canada” | False — registered and sold nationwide; concentration capped at 30% for adults |
| “Higher % is stronger” | Higher % lasts longer, not stronger; protection plateaus above ~30% |
| “DEET-free means safer” | Not necessarily — just means no DEET; check the alternative active and its % |
| “You can spray it on your dog” | No — human repellent only; use vet-approved products for pets |
| “It soaks dangerously into your blood” | Minimal absorption; rapidly metabolized and eliminated under labelled use |
How to Use DEET Safely
Getting the safety right is mostly about application habits:
- Choose the lowest concentration that covers your time outdoors — 20–30% for a long evening, less for a quick outing.
- Apply to exposed skin and the outside of clothing only — never under clothes.
- Do not spray directly on the face; spray your hands and pat it on, avoiding eyes and mouth.
- Keep it off cuts, wounds, and irritated skin.
- For kids, an adult should apply it, following the 10% and frequency limits in the table above.
- Wash treated skin with soap and water once you are back indoors, and wash treated clothing before wearing it again.
- For infants under 6 months, skip DEET entirely and use a mosquito net over the stroller or crib. Our guide to the best bug spray for kids in Canada covers age-appropriate choices.
Curious how DEET performs in an actual product? Our hands-on OFF! Deep Woods DEET review for Canada looks at concentration, duration, and where it fits.
This article is general information, not medical advice. It summarizes public guidance from Health Canada, the Public Health Agency of Canada, Public Health Ontario, the U.S. CDC, and the U.S. EPA. It does not diagnose, treat, or replace personalized advice. For any reaction, health concern, or question about your situation, contact your healthcare provider or pharmacist. In an emergency, or if a repellent is swallowed or gets in the eyes, call your local poison control centre or 911.