Is Thermacell Safe to Breathe?

Is Thermacell Safe to Breathe?Many people may have heard of the Thermacell device which is being touted as a miracle for repelling mosquitoes. As with most insecticides and insect repellants, many are curious if Thermacell is safe to use and breathe. So, is Thermacell safe to breathe?

Despite the fact that Thermacell is a fairly recently developed device, the science behind it is nothing new. In fact, the technology the Thermacell device uses to repel mosquitoes has been around for over half a century. Let’s take a look at the safety of the Thermacell device and its active ingredient, allethrin.

History of allethrin: the active ingredient in thermacell​

The main ingredient used in the Thermacell device is d-cis/trans allethrin. Allethrin was not created solely for use in the Thermacell device but was actually created in 1949. It is classified as a synthetic pyrethroid, which is a compound that is naturally found in chrysanthemum flowers.

Now, given that allethrin is a compound that mimics something that is found within chrysanthemums, it may sound like it is totally harmless. However, it is classified as an agent with a small amount of toxicity in certain situations. Still, in the amount that humans will be exposed to it in the Thermacell device, it is no more harmful than DEET or many other popular mosquito-repelling agents.

West nile virus is much more dangerous​

The reason that mosquito repellents are traditionally used is that mosquitoes themselves are a danger to human beings. For this reason, you have to weigh the dangers of mosquito exposure to the dangers of whatever repellent is being used. In this case, the minimal toxicity of allethrin is generally considered to be much less dangerous than possible exposure to the West Nile virus.

West Nile virus is still a problem in America, with almost 1000 cases of West Nile virus being reported in 2019. West Nile virus can be fatal in situations and is best avoided, especially amongst children and the elderly. Comparatively, allethrin and other heavy-duty insecticides used as repellants will cause mild irritation when inhaled at worst, and likely will cause no problems at all. 

How the thermacell device works​

The Thermacell device, or Thermacell lantern, is a fairly novel mode of insect repellant that functions as a small “lantern”. This doesn’t mean that it can be used to light your way, but simply that it emanates allethrin, similar to how a citronella lamp emanates citronella. However, allethrin is a bit more effective than common citronella when it comes to warding off mosquitos. 

Allethrin attacks the nervous system of mosquitos causing what is known as “knockdown”, resulting in paralysis or death. This means that not only are mosquitoes repelled by allethrin, but they can also be killed or rendered incapable of movement. For this reason, allethrin is often used as an insecticide in neighborhoods and other urban areas, sprayed at dusk or dawn.

The Thermacell device uses pads containing allethrin to give off an aura that is touted to protect at a range of 15 square feet. It uses butane gas that is lit to release the allethrin in the pads. Once the pad is used up, it can simply be replaced as many times as needed.

As allethrin is a tried-and-true method for eliminating mosquitoes, consumers have had a lot of luck with their Thermacell devices. Thermacell has become one of the top names in mosquito repellant in a relatively short period of time. If you are in an area with an extreme amount of mosquitos, using Thermacell in tandem with other repellents such as DEET and long-sleeved clothes can provide maximum protection.

Is thermacell safe to breathe?​

While allethrin exposure has a relatively small effect on humans, exposure to allethrin can be fatal to bees, cats, and fish. This means that if you’re taking your cat out camping, you may want to try something else, such as a citronella lamp. However, for most other pets, allethrin has minimal to no effect besides, of course, protection from mosquitoes.

Allethrin is what is considered a “non-persistent insecticide”, meaning it breaks down easily in the environment. For this reason, allethrin is generally safe to be used outside and will degrade over time, leading to minimal toxicity for those who breathe it. However, you are best to avoid ever using allethrin indoors or in any area without proper ventilation.

Because it breaks down outside, there are no harmful allethrin residues left when you are done using the Thermacell device. This means that you don’t have to worry about any harmful effects outside of the period of use. If you are concerned about any negative effects allethrin may have on you or your loved ones, you can simply limit your use of the Thermacell device to times of the day when mosquitoes are the most prevalent.

Of course, as with anything, certain individuals may be more affected by the allethrin present in the Thermacell device than others. While allethrin is generally regarded as having minimal toxicity in humans, some humans may have a more adverse allergic or asthmatic reaction to it. Because of this, you will want to pay careful attention when first using the Thermacell device, especially around little ones or pets.

Allethrin and thermacell have been approved for personal use

Above all, it’s important to reinstate that although allethrin is toxic to some creatures and can have some minimal effects on humans, it has been used safely and effectively for decades as an insecticide. Allethrin is routinely sprayed throughout highly-populated areas with no problems reported. Insecticides containing allethrin have been in commercial use for a long time, and there has been relatively few issues as far as human exposure.


The EPA has approved of both allethrin and the Thermacell device itself as a safe and effective means of repelling mosquitoes with minimal effects on the environment. Unless you are someone with extreme sensitivity, or a cat, use of the Thermacell device should pose few problems. As well, if you are in an area with lots of mosquitoes, the minimal problems that may be posed by allethrin exposure due to the use of the Thermacell device are likely going to be much less pertinent an issue than exposure to the West Nile virus.








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