Toxic Tick and Flea Products Affect Pets and Humans

The snow has not completely melted and the ticks are already making a play for Maya and Seamus. Looking back a year ago, as a new dog owner, I was instructed to buy a certain chemical product to apply to my pups, which would literally have the ticks and fleas falling dead to the floor. This, I thought to myself, is too good to be true; but because I was ignorant and advised by those I considered more knowledgeable, I bought a rather expensive 3-months supply of Frontline with the anticipation of a tick-free summer ahead. As I read the package instructions I was shocked to find that the chemical ingredients were so toxic they must be applied with latex gloves so as not to, as in never, touch my skin.

Yes, but what of my pups skin? If it is toxic to me, what must it be to their small bodies? You might think that I tossed the whole thing in the garbage on that realization, but no, I am ashamed to say that I did not. For two months I applied the toxic chemicals until one day I did my own research. What I found is shocking, perverted, untenable, and horrifying, but we Americans keep on poisoning our pets, along with ourselves and chemical companies continue to provide the loaded gun.

The active ingredient in Frontline is fipronil, an insecticide and member of the phenylpyrazole family of chemicals. Its purpose is to disrupt an insect’s nervous system functions. Well, hold on there doggie, according to the Journal of Pesticide Reform, “In tests with laboratory animals, fipronil caused aggressive behavior, damaged kidneys, and ‘drastic alterations in thyroid function.’ The fipronil-containing product Frontline caused changes in the levels of sex hormones.”

The other two toxic bad boys in Frontline are Methoprene, a neurotoxin that can cause liver enlargements, headaches, throat irritation and nausea and Ethanol, which can cause fatigue, lethargy, dizziness and nervous system disruption.

In her excellent 2008 Care2 article, The Surprising Poisons in Our Pets, Melissa Breyer reports that according to the Texas A&M Veterinary Medical Center, “dogs have much higher rates of cancer than people do, including 35 times more skin cancer, four times more breast tumors, eight times more bone cancer, and twice the incidence of leukemia.”

And here’s the kicker, the Environmental Protection Agency has classified fibronil as a carcinogen, because exposure to fipronil caused benign and malignant thyroid tumors in laboratory animals. All of which means it can cause cancer in both animals and humans.

You can be exposed to fibronil by petting an animal that has been treated with Frontline. The treatment persists for at least 56 days on pets. The good news is that the National Resources Defense Council (NRDC) has checked over a hundred tick and flea products finding that most of them contain chemicals toxic enough to cause harm to both pets and humans.  You should refer to their list before buying a product that may potentially harm your pet and contaminate yourself and your children. Fortunately, there are plenty of natural ways to control ticks and fleas in your environment. Care2 has a number of articles to help you out. Click HERE for a list of natural flea and tick control remedies.


Nathan Shook
Nathan Shook5 years ago

I use an all natural product from Its all natural and non toxic. Its been tested and proven to kill ticks and fleas 100%. Great product

S J6 years ago

I just used frontline to my boy as his vet recommended, I greatly regret it! I saw he tries to lick and scratch his fur near where I put it. I feel so bad! What can I do now?

Thanks for sharing.

Beth M.
Past Member 6 years ago


Aud Nordby
Aud nordby6 years ago


Milkah Savage
Past Member 6 years ago

I stray to stay as natural and chemical free as I can get with my angels. I can say though I have been useing "tea tree oil" for years and I find it works great. Im a strong believer that if I would eat it or use it than why would I do so to my angels. I wont. I try to keep them as natural and echo-friendly as me.

Ans Weevers
Ans Weevers7 years ago

thank you

Fred Krohn
Fred Krohn7 years ago

Use of various medications is always hazardous; look at penicillin allergy in humans. The best option is supervised application to determine the tolerance of the pet, if less toxic measures don't work. Just like a human seeking to avoid allergic or anaphylactic reactions to various drugs, a pet should also be treated as an individual. Most pets can tolerate small amounts of natural substances, but not all; even garlic should be used sparingly. For depletion of fleas in a house, the lamp-over-flypaper-based traps combined with things like baking-soda powdering and vacuuming should be adequate; taking everyone on vacation for a week while sulphur bombs or other gas grenade type pesticides are used should be a last resort.

Jennifer M.
Jennifer M.7 years ago

I did check the NRDC's list - they had classified Frontline as safe and were recommending it as a non-toxic alternative. they said that Fibronil was found non-toxic to humans and animals. So, when my vet recommended it today, I used it. Now I'm regretting it, after doing more research after the fact. Idk what to do, tho - the last time we had fleas, my cats almost died. One needed an emergency blood transfusion. But in all of my research, almost everything has been found dangerous. My vet said that she has seen some success with brewer's yeast. I think I'll try this. Right now, I'm using apple cider vinegar in the water and waiting for the Frontline to wear off. It is waterproof, so it doesnt wash off of the pet and become ineffective...

Tamara Austin
Tamara A8 years ago

Thanks for the heads up!

Sonny Honrado
Sonny Honrado8 years ago

We search for ticks from our dogs almost daily.