All chemicals, including insect repellents, have some degree of toxicity. However, the toxicity can vary by product and by route of exposure (eating, breathing, touching).
People that have left DEET products on their skin for extended periods of time have experienced irritation, redness, a rash, and swelling. People that have swallowed products containing DEET have experienced stomach upset, vomiting, and nausea. Very rarely, exposure to DEET has been associated with seizures in people.
DEET is a widely used repellent that deters pests by making it harder for them to smell humans. Despite being effective, it has faced controversy over potential health and environmental impacts, including skin irritation and toxicity concerns. Some countries have even banned DEET due to these risks.
The human health risk assessment concluded that there are no risks of concern because no toxic effects have been identified when used as a dermally applied insect repellent, and there is no dietary or occupational exposure for DEET.
If used improperly, such as if someone swallows it or applies too much, DEET can cause severe health effects like seizures, low blood pressure, uncoordinated movements or death, Dr. Kennedy said. But those cases are rare — seizures, for example, occur only once in every 100 million uses, according to the E.P.A.
There is no reliable evidence that deet causes cancer.
A Swedish study did find that men who used insect repellent for 115 days or longer faced an increased risk of developing testicular cancer.
Studies have shown that Picaridin is effective, safe and has fewer unpleasant qualities than DEET. Picaridin is odorless, does not melt plastics, or feel oily on skin.
Natural insect repellents
Examples of "natural" insect-repellent ingredients include citronella, geranium, peppermint and soybean oil. These are deemed safe but have not been approved for effectiveness by the EPA. Most of these keep insects away for only a short time. Some natural repellents can cause skin irritation.
Citing human health reasons, Health Canada barred the sale of insect repellents for human use that contained more than 30% DEET in a 2002 re-evaluation "based on a human health risk assessment that considered daily application of DEET over a prolonged period of time".
Mosquitoes are turned off by several natural scents, including citronella, peppermint, cedar, catnip, patchouli, lemongrass, lavender and more. You can add some of these plants to your landscaping to fend them off.
There is simply no evidence taking vitamin B will offer any significant protection from mosquito bites. In reality, if there was even moderate scientific evidence that taking a vitamin supplement could prevent mosquito bites, our supermarket shelves would be full of “mosquito repellent pills”.
Other insect repellents like N,N-diethyl-3-methylbenzamide (DEET) causes local irritation and discomfort when introduced into the eyes or oral cavity. Ingestions of DEET have also been associated with nausea, vomiting, hypotension, encephalopathy, seizure, coma, and ataxia (Chen-Hussey et al., 2014).
The use of currently registered products containing DEET in accordance with approved labeling will not pose unreasonable risks or adverse effects to humans or the environment. Therefore, all uses of these products are eligible for reregistration.
Unfortunately, despite marketing claims, these sprays don't just harm mosquitoes. The most widely used residential mosquito sprays are also highly toxic to native pollinators such as bees and butterflies, fish and other aquatic organisms, and they can even pose a risk to pets and people.
N,N-diethyl-3-methylbenzamide (DEET) remains the standard by which all other repellents are judged.
Oil of lemon eucalyptus is the most potent natural mosquito repellent. A DEET-free alternative to commercial mosquito repellent, oil of lemon eucalyptus is the only natural insect repellent recommended by both the EPA and CDC.
You can try diffusing lemon eucalyptus essential oil, or purchase a natural bug spray that has lemon eucalyptus oil as the natural ingredient. Oil of lemon eucalyptus (OLE) is the only natural ingredient that's CDC-approved as insect repellent (on par with DEET).
“We don't know exactly why, we don't know what it means to the mosquito, but it doesn't like it, and so it will jump away.” Research also suggests that picaridin may have some effect on mosquitoes' ability to sense odors, another trait it has in common with deet.
It's a chemical, after all — and bodies often react to chemicals. Some people experience rashes or irritated skin after using DEET. It can also irritate your eyes if sprayed too close to your peepers. More alarming, there have been rare reports of seizures associated with DEET.
Yes: DEET. A repellent with DEET tells mosquitos to buzz off loud and clear. You'll need one with at least 20% DEET to protect your skin for several hours at a time, although more than 50% doesn't work any better (kids should use 10%-30%).
Technical grade Picaridin has low acute oral, dermal and inhalation toxicity. It is classified as Toxicity Category IV for acute inhalation toxicity and primary dermal irritation and Toxicity Category III for acute oral, acute dermal and primary eye irritation. It is not a dermal sensitizer.
Use Environmental Protection Agency (EPA)-registered insect repellents containing DEET, picaridin, IR3535, Oil of Lemon Eucalyptus (OLE), para-menthane-diol (PMD), or 2-undecanone. EPA's helpful search tool can help you find the product that best suits your needs. Always follow product instructions.
The U.S. Department of Health and Human Services (DHHS) has not classified DEET as to its carcinogenicty (cancer causing ability). The U.S. Environmental Protection Agency (EPA) has determined that DEET in not classifiable as a human carcinogen.