Mosquitoes and DEET: FDA Approved So It Must Be Safe?

I sat with some tourists at the airport in Bangkok, who proudly announced they were "drowning themselves in high-strength DEET" to avoid Dengue Fever during their holiday in Thailand.  I must have looked horrified because they asked my opinion... haha.  And the best thing I could offer them was to try and summarize in a blog post the main reasons to AVOID DEET-based insect repellents, for their own health and the health of any future children.

So what is DEET anyway?  DEET (N,N-diethyl-meta-toluamide) is a synthetic chemical compound used in insect repellents to protect against fleas, ticks and mosquito bites and the spread of diseases such as Dengue Fever, Malaria, Encephalitis, West Nile Virus and Lyme Disease.  It was created in the USA in 1944 by the US Army in those same notorious laboratories that also brought us the highly toxic, cancer-causing Agent Orange.  Although approved by the USFDA as "safe for personal use", DEET has never been officially assessed or classified in terms of its carcinogenity (cancer causing agent) by either the US Department of Health & Human Services (DHHS) nor the International Agency for Research on Cancer (IARC).  Curious.

DEET has been the subject of some controversy due to potential health risks associated with its use, particularly in regards to birth defects, nausea, and gastric upset.

One of the main concerns about DEET is that it may be harmful to a developing fetus. According to the Environmental Protection Agency (EPA), studies in laboratory animals have shown that high doses of DEET can cause birth defects in subsequent generations. However, it's important to note that these studies were conducted on animals using much higher doses of DEET than people typically use when applying insect repellent, and there have been no studies in humans that have found a link between DEET exposure and birth defects.  One might also gently ask why no human studies have been funded in the last 75 years.

Additionally, DEET has been reported to cause nausea and gastric upset in some people. According to a study published in the Journal of Toxicology, exposure to DEET can cause symptoms such as headache, nausea, and vomiting. It may not be that spicy food or jetlag that's leaving you feeling poorly on day 2 or 3 of your holiday! It's important to note that these symptoms occur after exposure to large amounts of DEET, which stays in the bloodstream for up to 12 hours.

Another concern about DEET is that it may be toxic to the nervous system. According to a study conducted by the U.S. Environmental Protection Agency (EPA), DEET can cause behavioral and neurological effects in laboratory animals at high doses. These effects include tremors, convulsions, and death. Further studies in humans are needed to confirm these findings.

DEET is toxic for aquatic organisms and insects; it should never be sprayed directly on water surfaces and ironically it is advised never to use it directly on skin of pets.  Spraying DEET on yourself and then swimming?  A big no no environmentally.  But equally so is allowing it to wash down the drain into our waterways, rivers and oceans. 

Despite these concerns, the Centers for Disease Control and Prevention (CDC) and the American Academy of Pediatrics (AAP) continue to recommend the use of DEET as an effective way to prevent mosquito bites and the spread of mosquito-borne diseases. The AAP recommends that DEET products be used in concentrations of no more than 30% for children, and the CDC advises that DEET products be applied sparingly and only as needed.

In conclusion, DEET is controversial chemical officially considered by governments to be safe when used as directed, but which also has major concerns raised about the potential health risks associated with its use, particularly in regards to birth defects, neurological toxicity, nausea, and gastric upset.  Despite its official "Safe for Personal Use" status, the US Center for Disease Control does have an officially published ToxGuide for DEET poisoning.  You can view that HERE.

People who experience symptoms of DEET exposure should seek immediate medical attention. Anyone who is concerned about the potential risks of DEET should consider using alternative natural insect repellents based on neem extract, neem oil, picaridin or lemon eucalyptus essential oil, all of which have been clinically proven as equivalent and effective alternatives to DEET.


  1. Environmental Protection Agency. (2008). Reregistration Eligibility Decision (RED) for N,N-Diethyl-meta-toluamide (DEET)
  2. Journal of Toxicology (2012), 2012:959318.
  3. Centers for Disease Control and Prevention. (n.d.). DEET Insect Repellent Use and Safety.

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