If you’ve ever frantically doused yourself in bug repellent to ward off hungry mosquitoes while spending time in the Great Outdoors, you’re probably familiar with DEET. Its chemical name is N,N-Diethyl-m-toluamide (say that five times fast!), and since its development by the US Army in 1946, DEET has become the most active ingredient in insect repellents. But despite DEET’s success in fighting off biting pests like mosquitoes and ticks, it also has a bit of a bad reputation; I recently offered some to a pregnant friend, who declined because she feared harmful side effects. Plenty of companies sell DEET-free bug spray, marketed as a natural alternative without DEET’s potential toxicity and unpleasant smell. This made me wonder: Is DEET actually safe to use? I asked two board-certified dermatologists to weigh in.
Is DEET safe for human use?
According to dermatologist Dr. Marisa Garshick, MD, FAAD, DEET is completely safe and effective when used as directed. However, “it should not be used on children less than two months old,” she cautions. Dr. Snehal Amin, dermatologist and Mohs Surgeon, agrees that DEET applied topically to the skin or on clothing (never ingest it!) is safe for both children and adults.
“The EPA found no toxic effects on human health or significant environmental impact,” he confirms. “EPA studies on endocrine safety are pending, but have not been prioritized since the risk is considered low.” (‘Endocrine disruptors’ are chemicals, such as pesticides, that may mimic or interfere with the body’s hormones — but there is no current evidence that DEET is a disruptor.)
How much DEET is safe to use?
DEET concentrations in the forms of liquids, lotions, and sprays can range from 4 to 100 percent. This composition indicates how long the product will be effective. (A higher concentration does not mean the product will work better; it means it will work for a longer period of time). Dr. Amin adds that it’s probably wise to limit yourself to sporadic use of bug spray and choose concentrations lower than 20 percent.
Why does DEET have a reputation for being harmful?
DEET is neither intended nor safe for ingestion. Dr. Amin notes that oral intake can result in side effects such as nausea, vomiting, and (in rare cases) seizures. Since 1961, there have been at least six cases of toxic reactions from DEET exposure. Despite these seizure reports — which are likely responsible for lingering public fears — Dr. Garshick confirms that the overall incidence of DEET poisoning is very low. “Furthermore, the reports of DEET toxicity were generally when there was a misuse of the product in terms of application or ingestion,” she says. “It is not meant to be applied directly to open wounds or broken skin.”
Dr. Amin agrees. He specifically warns against spraying the product directly on your face, where it risks going into the eyes and mucosa; instead, he suggests, apply bug spray to your palm and then rub it onto your skin in the desired locations.
According to both dermatologists and the United States Environmental Protection Agency (EPA), DEET is also safe for use in pregnant women. Dr. Amin, however, advises that pregnant women pay close attention to the DEET concentration of the product they are using. “The more time spent outside, the greater the concentration you may need,” he says. According to a 2016 study published in the journal Obstetrics & Gynecology, safe insect repellent use during pregnancy includes the application of products at a concentration of 30 percent or less, avoiding products combined with sunscreen, and not reapplying more frequently than recommended.
Should you wash DEET off once you’re back inside?
Both dermatologists encourage washing off all insect repellent from the skin after returning inside, as prolonged exposure may lead to irritation, redness, or rashes. Consider taking a quick shower when you’re back from a hike or outdoor BBQ, and be sure to wash clothing that has been sprayed with DEET.
“Small amounts of DEET are absorbed through the skin into the bloodstream,” Dr. Amin says. “Over time and repeated exposure, this can add up. Covering the skin with clothing after applying DEET is not advised, as it results in increased systemic absorption. Additionally, do not apply DEET on broken or irritated skin, as this increases absorption into the bloodstream as well.” You have the most risk of getting a skin reaction if you use higher concentrations of DEET (like 75 percent) or are using bug spray more frequently.
Is DEET the only truly effective bug deterrent, or are there other products that work?
The insect repellents approved by the Centers for Disease Control and Prevention (CDC) include DEET, Picaridin, and oil of lemon eucalyptus. Both dermatologists agree these effective DEET-free alternatives can do the job in most contexts. “Picaridin is a new CDC recommended synthetic compound which is similar to a compound found in pepper plants,” Dr. Amin explains. This ingredient has been available in the US since 2005, and its efficacy is backed by research and tests done by Consumer Reports. Just keep in mind that Picaridin is much newer than DEET, which has been commercially available for many decades — meaning its safety hasn’t been as well-studied. Still, no evidence points to marked risk.
For a purer option, you can try Oil of Lemon Eucalyptus (OLE), a naturally sourced active substance that’s also used in some insect repellents and has proven effective against a range of biting bugs. Despite having similar names, OLE is an entirely different product from lemon eucalyptus essential oil; OLE is an extract from the leaves of the lemon eucalyptus tree that has been enriched for an active ingredient called para-menthane-3,8-diol (PMD). PMD can also be chemically made in a laboratory, and may even offer better protection against ticks than DEET does.
Lucky for all of us, mosquito season is almost over. In the meantime, if the DEET doesn’t stop ‘em all and you do get bitten by some pesky bugs before summer’s end, try this $10 gadget for instant itch relief — trust me, it works.