Permethrin For Dogs: How Harmful Is It?

permethrin for dogs

The dangers of pest preventatives including chews, collars, bandanas and spot ons are no secret. The chemicals in these products can cause serious adverse health reactions in dogs and humans. The US EPA received over 25,000 reports of pesticide reactions in the last 5 years … and this included 1,600 canine deaths.

Because of this, many dog owners are choosing to make a switch to natural flea and tick protection. The problem is, many insecticide treatments get marketed as “natural, safe and pet-friendly” to appeal to consumers. But after closer inspection, these so-called safe and effective solutions may not be as good as they seem. 

Today I want to talk to you about one of these “safe” preventatives. Permethrin is derived from plants but … it may not be as good for your dog as you thought. 

“Natural” Pest Prevention May Not Be Natural

Pest preventatives made with permethrin are flooding the market right now. Companies advertise them as friendly, safe and natural flea protection methods. 

As a dog owner, you may be thinking, “Finally, a minimally-invasive solution to flea control” …

Not exactly.

These products can fool consumers. It’s important to look at what makes these products “flea repellent.” These are not natural, safe remedies, but are instead full of synthetic insecticides. One of the worst is permethrin.

Is it safe to use permethrin on dogs? Despite that natural claim, not at all.

Before you buy any flea or tick preventatives, be sure to look at the ingredients

How Permethrin Can Hurt Your Dog

Permethrin is a pyrethroid, which is a synthetic compound used in insecticides. You can find permethrin in pesticide products including: 

  • Vectra #D (36.08% permethrin)
  • Liberty 50 
  • K9 Advantix II (used in combination with Imidacloprid, another dangerous insecticide) 
  • Defend EXspot Treatment 
  • Zodiac FleaTrol Spot On
  • Flea shampoos

It’s also used as a widespread insecticide in:

  • Agriculture
  • Gardening
  • Commercial household insecticides

Manufacturers will tell you permethrin is a synthetic compound derived from chrysanthemums – so it makes sense to think it’s safe and natural. But despite being an organic derivative, permethrin is a central nervous system poison. And it can cause neurotoxic symptoms.

Toxicity is also reported in dogs. In one case, permethrin caused tremors, facial twitching and salivation. 

This is because permethrin is more toxic than the chrysanthemum flower. It penetrates insect shells and paralyzes their nervous systems. In mammals, it also poisons the liver and paralyzes the muscular system. In studies, the organs of dogs exposed to permethrin increased in weight or size.

Along with being a neurotoxin, permethrin is an endocrine system disruptor. It poisons the thyroid, parathyroid, pancreas and reproductive system. If swallowed, it can also cause:

  • Liver damage
  • Gastrointestinal poisoning 
  • Neurotoxicity

Symptoms of permethrin toxicity in dogs include:

  • Incontinence
  • Tremors
  • Paralysis
  • Difficulty breathing
  • Nerve damage
  • Muscular paralysis or damage
  • Coma

Death is also a side effect.

The EPA has a “toxicity class” rating for commonly used pesticides. Level 1 is the most toxic and Level 4 is the least toxic. Permethrin toxicity is level 2-3, depending on the product.

Permethrin-containing products must also carry the word WARNING or CAUTION on their labels. You should use the same caution with flea products. The EPA even says that these products …

  • Are toxic to the nervous system of people and pets
  • Can trigger allergic reactions 
  • Are classified as “possible carcinogens

RELATED: Are chewable flea and tick preventatives safe? 

Permethrin Isn’t Just Bad For Your Dog

Permethrin is only found in dog-specific flea treatments because it’s highly toxic to cats and fish. It’s also usually saved for topical treatments. That’s because oral use can lead to liver failure and neurological damage. 

That means there are many situations that could put your dog and other animals at risk of illness or death. 

  • Your dog chews his flea bandana or collar
  • Someone puts it on a cat not knowing the dangers 
  • One of your pets licks a spot on off another pet
  • A cat finds a flea bandana or collar on the floor
  • Your dog goes swimming in a lake or body of water with fish 

Even worse, the pyrethroids found in flea bandana products are also highly toxic to:

The EPA even claimed that “flea resistance is an issue for effectiveness”. That means that despite all the toxicity, it might not even actually repel fleas in the first place. 

Products with permethrin may appear harmless … but they’re dangerous to the health of you, your pet, and the environment. And they may not do the job they’re intended for. 

What If I Bought A Flea Bandana?

The best way to reduce exposure to permethrin is to avoid …

  • Topical flea medications
  • DEET
  • Flea collars 
  • Flea bandanas

But what if you already bought one?

If you purchased a permethrin-based pest preventative for your dog, stop using it right away. And watch for the warning signs that your dog may be sick.

Symptoms include:

  • Contact dermatitis (on-site itching, hives, or redness)
  • Swelling
  • Asthma-like breathing problems
  • Sneezing
  • Nausea
  • Loss of coordination
  • Convulsions
  • Vomiting

In people, symptoms include:

  • Contact dermatitis
  • Rashes
  • Irritation
  • Endocrine system disruption

The best flea and tick prevention shouldn’t harm your dog. So, toss the permethrin and go with a natural alternative like homemade flea and tick prevention.

DIY Permethrin-Free Flea Control

You don’t have to use insecticides or pesticides to keep your dog free of fleas. There are natural alternatives.

If you’re looking for non-toxic flea and tick protection, try making your own flea bandana or collar. Or you can try one of our other natural flea and tick spray recipes!

Permethrin-Free Flea Bandana Or Collar

What you’ll need:

  • A regular dog bandana, collar or strip of fabric
  • 2 tbsp almond oil
  • 2 drops of a flea repelling essential oil (you can try cinnamon, rosemary, peppermint or cedarwood)


  • Mix the oils together and apply them to the collar or bandana. Only use a total of 2 drops, not 2 drops of each oil.
  • Allow it to dry for about 1 hour before placing on your pet.
  • Remove when your pet is indoors. 
  • Re-soak once a week, as needed.

You can also buy natural flea and tick repellents. If you do, be sure that they don’t contain pennyroyal, wintergreen or clove. These can be dangerous for your dog. 

RELATED: More natural flea and tick repellent recipes …References


Boland LA, Angles JM. Feline permethrin toxicity: retrospective study of 42 casesJournal of Feline Medicine and Surgery. 2010 Feb;12(2):61-71. 

Drago B, Shah NS, Shah SH. Acute permethrin neurotoxicity: Variable presentations, high index of suspicionToxicology reports. 2014 Sep;1:1026-28.

Klainbart S, Merbl Y, Kelmer E, Cuneah O, Shimshoni J. Bifenthrin toxicity in a dogAnnals of Clinical Pathology. 2014 Nov 04;2(4):1030.

Macwelch T. The toxic truth about DEET and permethrinOutdoor Life. 2012 Apr 10. 

Rust M. Insecticide resistance in fleasInsects. 2016 Mar 17;7(1):10.

Klainbart S, Merbl Y, Keimer E, Cuneah O, Edery N, Shimshoni JA. Tremor-salivation syndrome in canine following pyrethroid/permethrin intoxicationPharmaceutica Analytica Acta. 2012;5(9).National Research Council (US). 7 liver and other organ toxicity of permethrin. 1994.

Related Posts

Popular Posts