Around since the 1940s, DEET, or diethyltoluamide, remains the gold standard for protection against mosquito-borne illnesses like West Nile virus, Zika or malaria and tick-borne illnesses like Lyme disease and Rocky Mountain spotted fever. "As a general rule, I'd say there's DEET and then there's everything else," says Bruce Farber, MD, an infectious disease specialist with Northwell Health. "It's the tried-and-true option."
DEET is now found in more than 500 products. Although it's possible to buy up to 100 percent DEET, that's not necessary and could cause skin irritation. A formula that contains 25 to 30 percent will provide eight hours of protection against both mosquitoes and ticks, says entomologist Joseph Conlon, technical advisor for the American Mosquito Control Association.
The downside is that this chemical makes some people uneasy because it's been associated with neurological problems. That sounds scary—until you hear the details: "While there have been isolated reports of neurological damage and brain toxicity in rats, these reports have not translated to any real dangers in humans," says Robert Glatter, MD, assistant professor of emergency medicine at Northwell Health. In other words, if you don't use it on rats and you use it as directed—by spraying it on your body, not drinking it as some people have actually done—you should be just fine.
"I recommend the use of DEET for my family and my patients," says Dr. Glatter. “The CDC and the Environmental Protection Agency both agree that products containing DEET are safe to use in anyone over two months old.”