Why can’t I use my dog’s tick prevention medicine?

The treatment isn't toxic to us, but it still wouldn't work very well.

Tick season is in full swing, which means the tiny pinhead buggers are likely lurking in the tall grass along your hiking trail or clinging to the overgrown bushes in the woods by your home. For humans, regular tick checks are part of the summer routine. For furry hiking companions, though, there’s a far simpler strategy: products like Frontline and Advantix go on once, and protect against pests for an entire month.

Unfortunately, no similar products exist for humans—we don’t have one-time use methods that can keep the bugs at bay for an extended time. But they seem to work so well for our canine best friends, so why don’t we have them?

Thomas Mather, an entomologist and the director of the TickEncounter Resource Center at the University of Rhode Island, says its not because the active ingredients wouldn’t work for people, or that the materials are wildy toxic. It’s likely because we bathe much more regularly than dogs do.

Spot-on repellent treatments, like Frontline, are squeezed out of an applicator onto a dog’s back. The medication diffuses across the oils of their skin and into their hair follicles, and its released from there throughout the month. If you give your dog too many baths, the treatment can lose its potency, Mather says—so in people, who probably shower every day or every other day, it likely wouldn’t last very long.

“People would wash it off,” Mather says. “It would be something you had to reapply all the time.”

Flea and tick-prevention collars, like Seresto, work in a similar way—by releasing an active medication onto an animal’s skin. But humans wouldn’t be able to just put it on their ankle and see the same effect, Mather says. “People wouldn’t keep it on all the time, and you don’t get the protective benefit if you keep putting it on and taking it off.”

The products are essentially pesticides, which kill or impair ticks (and fleas, and other bugs) on contact. Frontline is made from Fipronil, which is also used in agriculture and for indoor pest control. It’s considered moderately hazardous by the World Health Organization, though there hasn’t been much research into its effects on human health. Right now, it isn’t a part of any products intended for human use.

The other major tick-preventing pesticide, permethrin (which is found in Advantix), is a component of medications already in use for people: like rinses to treat lice, or lotions for scabies, a condition where small mites bury into the skin.

In the early 1990s, Mather developed and patented a permethrin soap, with the idea that it would facilitate regular application of the tick-preventing chemical. “I did experiments with hamsters, and showed that if you wash hamsters infested with deer ticks you could prevent [them] from being infected with Lyme,” he says. Mather says he offered his formulations to some drug companies for further testing and potentially to create into a product intended for human use, but none took it up.

Permethrin products to prevent ticks and fleas are already on the market, in the form of permethrin-treated clothing. The chemical can bind to fabric, and repel or kill bugs even after its been washed multiple times. Research shows that wearing treated clothing can significantly cut down on ticks and tick bites, and the pesticide is better at warding off ticks than DEET, the ingredient in most bug sprays.

The United States military has used permethrin-treated clothing since the 1990s, and it hasn’t shown any significant safety concerns. “The military has used this technology for years,” Mather says. “It’s not clear why it’s not more widely used in general.”

Creating a long-term, long-lasting product might be theoretically possible for humans, Mather says, but it would take a company devoting resources towards creating one. While there haven’t been any major toxicity concerns with permethrin thus far, in order to create a product for widespread public use, companies would need to do far more testing to figure out what the safe level of the product is.

In the meantime, he says, it’s best to save the currently available products for the non-human animals in the house.