Thermacell is non-toxic and virtually scent-free. It doesn’t sit on the skin and instead disperses in the air around you. That’s great – but are we sure it is safe to use?

Thermacell is known to be safe for adults, kids and pets alike. It does not contain DEET or other harmful chemicals that are widely known to cause serious side effects when used regularly. The chemicals in Thermacell are safe to handle and use.

It’s nice to know that Thermacell is safe and effective. If you want to learn more before you use it on your next trip, read on.

What Is the Active Ingredient in Thermacell?

With Thermacell devices, there are three active ingredients used in repelling mosquitos and other biting insects. These chemicals include allethrin, prallethrin or metofluthrin which act as an insecticide for the device when activated by heating elements. 

What Is Allethrin?

Allethrin is a synthetic copy of pyrethrins, which are found in natural chrysanthemum flowers. It inhibits the ability of insects to breathe and causes them to die within minutes after they touch it or eat it. Allethrin has also been shown to be effective against mosquitoes, flies, ticks and fleas. The fuel-powered Thermacell devices use allethrin or prallehtrin as the active ingredient.

What Is Prallehtrin?

Prallehtrin is less benign than allethrin, and may be toxic if directly inhaled. But with the Thermacell system, prallethrin is dispersed evenly thoughout the air and should never be directly inhaled.

What Is Metofluthrin?

The rechargeable platform of Thermacell products uses metofluthrin as the active ingredient. This the least benign of the potential active ingredients in Thermacell products, as small animals and dogs showed signs of sensitivity to it, according to the EPA.

How to Use Thermacell

When using the device, you should be at least 15 feet away from open flames and other heat sources.  And keep in mind that it only protects the area where it is being used – so if you are camping with a group of people, make sure they all have their own unit.  

The devices are meant to be stationary, so they can establish the radius of protection. While the device is working, it is best not to stand in the zone.

Should You Use Thermacell While Eating?

The makers of Thermacell recommend not using their devices around uncovered food. They advise to move any food outside of the zone of protection. Thermacell should not be activated while you are eating.

If you would like to eat in a mosquito-friendly zone, you may activate the device well in advance of eating, then turn it off for 10-15 minutes before serving food so the chemical can disspate. After eating, the device can be turned back on.

Will Thermacell Harm Fish and Wildlife?

As mentioned earlier, some of the chemicals used in certain Thermacell products – namely, the metofluthrin used as the active ingredient in the rechargeable platform of Thermacell – can adversely affect fish and small animals. It is a neurotoxin.

But Thermacell strictly advises against using Thermacell in water. And metofluthrin is used in other insect repellents, too. If used safely and according to directions, Thermacell should not harm any wildlife at all.

Can Thermacell Be Used Indoors or Inside a Tent?

Thermacell cannot, under any circumstances, be used in enclosed spaces. To offer tent protection when camping, place the unit outside the tent as the center of the radius to be protected. Never put the unit inside the tent or other enclosed area.

To protect your tent safely against mosquitos and other insects, make sure you keep your tent fly closed and employ mosquito netting over the tent, if necessary. There is really no safe spray or device for indoor use. Instead, do all you can to keep flying pests outside – then repel them safely out there.

Can Thermacell Be Used Near Candles or Campfires?

You do not want to engage Thermacell in an area that has a citronella candle burning – or any candle for that matter.

Thermacell should not be used or stored near a campfire or burning candle. Thermacell and the EPA both warn to keep Thermacell away from open flames.

If you want to protect your campfire area, you may want to burn citronella leaves or other insect-repelling herbs. Most insecticides are not compatible with an open flame. And, lucky for us, many flying insects are kept away by the smoke of a campfire.