Comfortis Side Effects

The Scoop on Your Dog’s Flea Pill

comfortis flea pills

The thought of instant flea removal is extremely appealing, but can Comfortis do what it claims without making your pet ill?

That’s what we’re going to find out over the next few paragraphs.

The active ingredient in Comfortis is Spinosad, an environmentally-friendly neurotoxin that kills fleas by exciting their nervous systems, causing paralysis and death.

What Are the Side Effects of Comfortis For Dogs?

First and foremost, you should know that the FDA has received reports of adverse effects in dogs who take spinosad and that are also taking high, extra-label dosages of ivermectin. That’s an insecticide found in Hartgard Plus, Iverhart Plus and regular Heartguard, among others.

Side effects are fairly uncommon with spinosad but include:

  • Vomiting – this is the most common by far
  • Hyperactivity
  • Lethargy
  • Increased appetite
  • Diarrhea
  • Drooling
  • Excess vocalization
  • Hives or red skin

If your dog experiences any of these side effects, stop use and contact your vet immediately.

Can Comfortis safely Kill Fleas On Dogs?

In the overwhelming majority of cases, yes this product is a safe, effective way to help keep your pet flea-free. Don’t use if you’re also using a product with ivermectin in order to avoid drug interactions. Also, to reduce the chances of nausea and vomiting, administer with food and if he does vomit within a few minutes, give him another full dose.

To find a great deal on Comfortis from the comfort of your home, click here.

If you’ve used Comfortis, please let us know about your experience in the comments section below.

8 Responses to “Comfortis Side Effects”
  1. Debra Berger says:

    5/18/2015 My daughter’s dog Chewy, a 4 year old collie mix, was a healthy, happy, active dog. He had been given Comfortis in April and received his second dosage on May 16, 2015 along with his evening meal. He ate his meal and Comfortis at approximately 6:30 pm after which he laid down with his companions for their usual evening nap. At about 7:15 pm, we noticed that Chewy had lifted his head and appeared to be following a bug in the air with his eyes and head. His head then fell backward. He let out a horrifying, long howl and died in my arms. Our veterinarian also feels his death was directly related to the Comfortis and a necropsy is being performed on Chewy at University of Georgia in Athens, GA. We should have some results this week, but we found out today that Elanco, which is the distributor of these products, is part of the “President’s Club” at the university. They are paying for the necropsy so we are very skeptical that the results will be anything but “inconclusive”.

    These products to not list “death” as a possible side effect. Yet the chemical, Spinosad, is a neurotoxin that kills fleas within 30 minutes. When these bugs die, they seize, convulse, are paralyzed and die… the same way that the dogs appear to die shortly after taking the drugs, just like Chewy.

    Please carefully consider the fact that you are giving your pet a deadly pesticide that can potentially kill you dog. They have just released a new product that is for cats, so I fully expect that there will be many more posts now that include cats in these death and reactions reports.

    • Ursula K says:

      I realize it has been two years, but what was the outcome?

  2. kenny rogers says:

    I gave my dog comfortis, and the next day she started vomiting and stopped eating,For several days she would not eat and she stopped drinking water cause every time she did she would throw up,carried her to the vet and they had to keep her for several days. with iv fluids kidney and liver problems,they got her back up only with the help of iv, they took her off 06/02/2015 but still not eating and very weak. BUT SHE WAS ALL GOOD BEFORE GIVING HER THIS COMFORTIS THAT IS WHEN SHE WENT DOWN VERY QUICK! AND SHE SHE MIGHT NOT PULL OUT OF IT . ALL LEFT UP TO THE GOOD LORD NOW, MIGHT HAVE TO TAKE HER BACK AND HAVE HER PUT TO SLEEP! NO MORE COMFORTIS FOR MY DOGS IF I GET ANOTHER ONE.

  3. Norma A villalobos says:

    I gave my 8 lb chihuahua Comfortis last week. He later was constipated followed by very loose stools. His appatite is completely gone for 4 days now and I am forcing water on him. Very very concerned.

  4. helena madsen says:

    The side effects are increasingly worse ,I will never use this product again. Pet companies do not consider the animals enough.

  5. Marie says:

    Good grief, out of the millions of doses of comfort is, brovecto, trifexis, etc. Millions of dogs are fine. My neighbors and daughter use them all the time. I just ordered some. My dogs are infested and getting sores. I’ve spent $1500 in 4 months for the best on the market yard treatment. I can’t bath and spray, also a chemical, them everyday. Do I just let them suffer horribly? It’s like all the prescription meds in the world, some people die and there are thousands of lawsuits. Chemo killed my friend and many other’s. Should they had not tried? I’m so sorry for your losses but my dog’s are suffering. Any other ideas for them?

    • Donna Warlick says:

      Thanks for a voice of reason. You’re right, any animal and any person can suddenly die of an allergy or bad reaction. I will die if I eat an avocado. I am not posting pleas to take them off the market.

  6. Tanalyn says:

    Comfortis made both my dogs ill (vomiting and lethargy). They are smaller dogs (12 lbs and 22 lbs). I contacted Elanco for a full refund and they said they would think about it. I submitted an adverse product reaction to the FDA. All consumers should do this so they can track the adverse effects of this product. Elanco has a pathetic policy with consumers.

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