Don't Bother Using Your Tick Repellent Unless It Has These Ingredients

Summers would feel a whole lot nicer if we didn't have to worry about ticks. But sadly, we live in a world where these blood-sucking arachnids are both common and dangerous. Of all disease-vectoring pests, ticks are responsible for more than 90% of disease cases in the U.S., including Lyme disease, according to the Johns Hopkins Bloomberg School of Public Health. So, to break the chain of disease transmission and protect yourself against bites when you venture outdoors, it's important to apply tick repellents.

However, your tick repellent is most likely to be effective if it contains active ingredients approved by the U.S. Environmental Protection Agency (EPA). These include DEET, a formula most Americans are already familiar with, as it has been in circulation since the 1950s and is widely used against all sorts of biting insects, including mosquitoes and flies. More recently, picaridin, another synthetic chemical that mimics repellent compounds of pepper plants and is synthesized by Bayer, is also becoming popular.

You may also look for repellents containing Oil of Lemon Eucalyptus (OLE), which surprisingly isn't an essential oil. Instead, it's synthesized artificially to mimic PMD (p-Menthane-3,8-diol), a naturally occurring compound in lemon eucalyptus plants, which has, in turn, earned EPA approval as an insect repellent. IR3535 is another ingredient that's known to be effective against Lyme-vectoring deer ticks. Other than these, the EPA has also approved 2-undecanone and nootkatone against ticks, though the commercial offerings are slim to none as of yet. That being said, if you're looking to tick-proof your clothing and camping gear, you may use permethrin-containing repellents, but keep them off your skin.

Choosing tick repellents based on their active ingredients is a brilliant start, but you must also check their potency. That's because the duration of protection is directly correlated with it. In other words, the higher the percentage of active ingredients, the longer you'll remain protected. However, other variables like overall formulation, water exposure, sweat, and your attractiveness to pests may also play a key part.

Take DEET products, for instance. You'll find them in the range of 4% to 100%. To protect yourself from ticks for a short while, say under two hours, you can get by with a 10% concentration. However, if you'll be in a heavily infested area or are likely to sweat off the repellent due to hot, humid weather, you'll want a product with at least 30% DEET. In any instance, don't exceed 50%, as DEET protection plateaus past this level. Generally, you should start with the lowest concentration and work your way up to minimize the risk of irritation.

Similarly, if you're buying tick repellents containing picaridin or IR3535, you'll need these active ingredients to make up at least 20% of the total product to get the maximum protection. This percentage shoots up to 30% for OLE. As for 2-undecanone, the jury is still out on the maximum concentration necessary to provide DEET-level protection. Since it occurs naturally in wild tomatoes, it may need to be used in higher concentrations to be effective, though it also appears to be relatively less toxic.

When you want to say goodbye to ticks, technically all products containing EPA-approved active ingredients should work, as Consumer Reports (CR) also found in its limited testing. What sets them apart is the duration of protection, texture, odor, age of the applier, and safety. According to the Global Lyme Alliance, most DEET repellents repel ticks for at most eight hours. This duration may go up to 14 hours and 11 hours, respectively, for picaridin and IR3535 products, depending on the formula's strength and environmental exposure. OLE, on the other hand, offers limited protection, lasting around six hours at a 30% to 40% concentration. In fact, you must ensure that the label specifically lists ticks, as some OLE products only work against mosquitoes.

If you've used a DEET bug repellent before, you'll know it stinks like a skunk and leaves an oily residue that can greatly damage plastics and synthetic fabrics. Also, the CDC notes that excessive exposure can lead to skin irritation and, in rare cases, neurological symptoms such as seizures. Moreover, the American Academy of Pediatrics advises against using DEET on infants younger than 2 months and recommends using it cautiously on older children. Picaridin, in contrast, doesn't share many of DEET's downsides, making it less likely to damage fabrics and generally well tolerated by adults and children. However, its effects on pregnant women are understudied. IR3535 is similarly safe for everybody but may irritate the eyes if misapplied. OLE shouldn't be used on children below the age of three.