Bug spray is not dangerous for most people when used as directed. The active ingredients in common repellents have been studied for decades, and serious reactions are extremely rare. That said, these products are designed to repel insects through chemical activity, so they do carry some risks, especially with misuse, overapplication, or exposure to vulnerable groups like young children and pets.
What Happens When Bug Spray Touches Your Skin
The most widely used repellent ingredient, DEET, absorbs through skin at a relatively low rate. In human studies, about 5.6% of a pure DEET dose applied to the forearm was absorbed over eight hours. When DEET was mixed in an alcohol-based solution, absorption rose to 8.4%. Picaridin, the other popular synthetic repellent, showed similar numbers: less than 6% absorption through human skin over eight hours in lab conditions.
Once absorbed, both compounds are processed by the liver and excreted through urine. At normal application levels, neither builds up in the body in meaningful amounts. The most common side effects from skin contact are mild: irritation, redness, rash, or a tingling sensation. About 5% of DEET-related reports to poison control centers involved skin symptoms, and those were typically minor and short-lived.
Serious Reactions Are Exceptionally Rare
The headline risk people worry about with DEET is neurological effects: seizures, tremors, or worse. These reactions do exist in the medical literature, but the numbers tell a reassuring story. Between 1961 and 1998, the estimated rate of seizures following DEET exposure was roughly 1 per 100 million users. Nearly all reported neurological cases involved someone accidentally swallowing the product or applying it in ways that directly contradicted label directions, like soaking clothing or applying it to broken skin repeatedly.
Eye exposure is actually the most frequently reported problem. Getting bug spray in your eyes can cause pain, irritation, and excessive tearing. In animal studies, direct eye contact with concentrated DEET caused moderate to severe irritation that generally cleared within five to seven days. The practical takeaway: spray it on your hands first, then apply to your face, keeping it away from your eyes and mouth.
How Different Ingredients Compare
Not all bug sprays use the same active ingredient, and the safety profiles differ slightly.
- DEET remains the most studied repellent. It’s effective across a wide range of concentrations (10% to 30% for most consumer products) and has a long safety track record. Higher concentrations don’t repel better; they just last longer.
- Picaridin is classified as practically non-toxic by inhalation and is not considered a skin irritant or sensitizer. The EPA classifies it as “not likely to be carcinogenic to humans,” and no evidence of hormone disruption has been found. Allergic reactions have been reported but are rare. One documented case involved a man who developed contact dermatitis from a 10% picaridin product, though he reacted to both the picaridin and another ingredient in the formulation.
- Oil of lemon eucalyptus (OLE) is the main plant-derived option registered with the EPA. Products with 30% to 40% concentration provide about six hours of protection, while lower concentrations (8% to 10%) last roughly two hours. It should not be used on children under 3 years old. Importantly, “pure” oil of lemon eucalyptus is not the same as the refined, EPA-registered version and has not been tested for safety as a repellent.
Permethrin Is a Different Category
Permethrin-based sprays are designed for clothing, gear, and fabrics, not skin. This distinction matters. Permethrin kills insects on contact and remains active on treated clothing through multiple washes. On human skin, it can cause tingling, burning, or itching at the contact site. Inhaling permethrin spray during application can irritate the nose and lungs and cause headaches, dizziness, or nausea.
The bigger concern with permethrin is pets, especially cats. Cats metabolize permethrin far more slowly than dogs or humans. Cats accidentally exposed to products containing high concentrations (45% to 65%) of permethrin can develop anxiety, loss of coordination, muscle tremors, seizures, and can die from the exposure. If you treat clothing with permethrin, keep it away from cats until it’s fully dried and stored.
Children Need Extra Caution
DEET and picaridin are considered safe for children over 2 months old when applied by an adult. Oil of lemon eucalyptus products carry a firm age cutoff: do not use them on children younger than 3. For any repellent, the application rules for kids are stricter than for adults. Don’t let children apply it themselves, avoid their hands (which end up in their mouths), and wash treated skin as soon as they come indoors.
For infants under 2 months, the safest approach is physical barriers like mosquito netting over carriers and strollers rather than chemical repellents.
Sunscreen and Bug Spray Don’t Mix Well
Using sunscreen and insect repellent together is common, but combining them changes how your skin absorbs both products. Repellent absorption through skin normally ranges from about 3% to 19%, and layering sunscreen underneath can push that number higher. The CDC recommends against using combination sunscreen-repellent products for a practical reason: sunscreen needs reapplication every couple of hours, while most repellents last much longer. A combo product tempts you to either reapply repellent too often or not reapply sunscreen enough.
If you need both, apply sunscreen first, let it dry completely, then apply repellent on top.
How to Reduce Your Risk
Most of the harm from bug spray comes from misuse rather than normal application. A few habits eliminate the vast majority of risk:
- Apply sparingly. The EPA specifically recommends using DEET sparingly, not generously. A thin, even layer is all you need.
- Don’t spray it on cuts or irritated skin. Broken skin absorbs more product, and this is a common factor in the rare serious reactions reported.
- Wash it off when you’re back inside. Wash treated skin and clothing before wearing them again. There’s no benefit to leaving repellent on once you’re no longer exposed to insects.
- Choose the right concentration for the right duration. Products with less than 10% active ingredient typically protect for only one to two hours. If you’ll be outside for a short time, a lower concentration works fine and means less chemical exposure overall.
- Spray in ventilated areas. Inhaling aerosolized repellent is one of the more common ways people experience symptoms like headaches and nausea. Spray outdoors or in well-ventilated spaces, and consider lotions or pump sprays over aerosols.
The bottom line is straightforward: for the overwhelming majority of people, the health risks from bug spray are minor and avoidable, while the diseases carried by mosquitoes and ticks (Zika, West Nile, Lyme, malaria) are not. Used correctly, repellents are one of the safer tools in your medicine cabinet.