Comfortis Chewable Tablet for Dogs, 60.1-120 lbs, (Brown Box), slide 1 of 1

Comfortis Chewable Tablet for Dogs, 60.1-120 lbs, (Brown Box), 6 Chewable Tablets (6-mos. supply)

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Comfortis is a chewable medication prescribed by veterinarians for dogs and cats to help treat -- and possibly even prevent -- flea infestations for up to one month. These flavored tablets can be added to your pet's favorite food and only need to be given to your canine companion once a month to help combat fleas.


Comfortis kills fleas and is indicated for the prevention and treatment of flea infestations, for one month, on cats and kittens 14 weeks of age and older and 4.1 pounds of body weight or greater.

Possible Side Effects

The most common side effect reported in dogs is vomiting.

Drug & Food Interactions

There are no known drug interactions while using Comfortis.


Comfortis chewable tablets are for use in dogs and puppies 14 weeks of age and older. Use with caution in breeding females. Use with caution in dogs with pre-existing epilepsy. The safe use of Comfortis chewable tablets in breeding males has not been evaluated.

Dosage Chart

Color on BoxWeight RangeStrengthDosageProduct Page
PinkDogs 5-10 lbs / Cats 4.1-6 lbs140 mg SpinosadGive orally once a month✓-Click Here
OrangeDogs 10.1-20 lbs / Cats 6.1-12 lbs270 mg SpinosadGive orally once a month✓-Click Here
GreenDogs 20.1-40 lbs / Cats 12.1-24 lbs560 mg SpinosadGive orally once a month✓-Click Here
BlueDogs 40.1-60 lbs810 mg SpinosadGive orally once a month✓-Click Here
BrownDogs 60.1-120 lbs1620 mg SpinosadGive orally once a month✓-Click Here
  1. Prescribing Information

See all items by Comfortis

  • Item Number
  • Generic Name
  • Common Brand Name(s)
    Comfortis, Trifexis
  • For Use With
  • Administration Form
  • Usage
    Prevention, Treatment
  • Brand
  • Lifestage
    Adult, Senior
  • Breed Size
    Large Breeds
  • Product Form
    Chewable Tablet
  • Strength
    1620 mg Spinosad
  • Health Condition
  • Drug Type

1620 mg Spinosad.

Recommended Dosage

Dose varies based on pet's weight. Use according to your veterinarian's instructions. Comfortis is generally given once a month, but you should always follow your veterinarian's directions. It is recommended to give Comfortis chewable tablets with food.

Storage Instructions

Store at temperatures between 68° - 77°F.


What are Comfortis (Spinosad) Tablets?

They’re beef-flavored, chewable tablets you give to your dog to kill fleas and prevent flea infestations for one month. Comfortis chewable tablets are recommended for monthly use in dogs 14 weeks of age or older and 5 lbs of body weight or greater.

What is Spinosad?

Spinosad is the active ingredient in Comfortis. It belongs to a class of antiparasitics known as spinosyns, which are derived from a naturally-occurring soil microbe. It works by attacking the nervous system of insects, causing the rapid death of adult fleas.

When should treatment with Comfortis begin?

Treatment can begin at any time of the year. Comfortis is most effective when given one month before fleas become active, with continued monthly dosing through the end of the flea season. In areas where fleas are common year-round, monthly treatment with Comfortis chewable tablets should continue through the entire year without interruption. To minimize the likelihood of flea re-infestation, simultaneously treat all animals in your household with an approved flea protection product. Consult your veterinarian for the flea treatment options most appropriate for your area. See also, what should I discuss with my veterinarian regarding Comfortis for my dog?

How quickly will Comfortis (Spinosad) kill fleas?

Spinosad, the active ingredient in Comfortis, began killing fleas in 30 minutes and killed 100% of fleas on dogs in just four hours in controlled laboratory studies. Comfortis chewable tablets kill fleas before they can lay eggs.

How long does Comfortis last?

Comfortis has demonstrated full effectiveness for an entire month.

Does seeing fleas on my dog mean the treatment isn't working?

Comfortis kills fleas before they can lay eggs when used monthly, according to the label directions. If you see fleas on your dog within a month after your pet receives Comfortis, they are most likely new fleas. Because your pet has been treated with Comfortis, these new fleas will be killed before they can produce eggs that contaminate your home. Continued monthly use of Comfortis can prevent any new flea infestations.

Your pet can experience continued exposure to fleas living in the environment. It’s important to treat all animals in the household with an approved flea product to help control the flea population. Learn more about controlling flea infestations in your home.

Is it safe to give Comfortis (Spinosad) to my dog?

Comfortis has demonstrated to be safe in healthy dogs when used according to label directions. Use only for dogs and puppies 14 weeks of age and older and 5 lbs of body weight or greater. The safe use of Comfortis in breeding, pregnant or lactating dogs has not been evaluated.

My pet has allergies, can he still take Comfortis?

Comfortis contains beef flavoring made from a pork-based protein. If your pet has an allergy to pork, you may need to consider an alternative for flea treatment and prevention. Please discuss these options with your pet's veterinarian. The use of ivermectin at higher than FDA-approved doses at the same time as Comfortis can result in serious side effects.

What side effects might occur with Comfortis?

As with any medication, sometimes side effects occur. See the Comfortis label for complete safety information.

The most common adverse reaction reported is vomiting. Other adverse reactions reported in decreasing order of frequency are: depression/lethargy, decreased appetite, incoordination, diarrhea, itching, trembling, excessive salivation and seizures. Following concomitant extra-label use of ivermectin with Comfortis, some dogs have experienced the following clinical signs: trembling/twitching, salivation/drooling, seizures, ataxia, mydriasis, blindness and disorientation. See the Comfortis label for complete safety information.

How should I give Comfortis (Spinosad) to my pet?

Administer Comfortis with food for maximum effectiveness. Because Comfortis is a flavored tablet, it can be offered just prior to or just after feeding. You can also administer Comfortis as you would other tablet medications. Visit the Dosing & Administration page for more details, or download the Comfortis label. Each box includes reminder stickers for your calendar to help remind you to administer each dose. You can also sign up for monthly text or email reminders.

How much food do I have to give my pet when administering the Comfortis Tablet?

In field trials, dog owners were instructed to give the Comfortis tablet with food. However, the quantity of food was not specified and Comfortis was still effective. An option is to give Comfortis immediately before a regularly scheduled meal. For free feeders (dogs who nibble throughout the day), you might take food away at night, administer Comfortis first thing in the morning, then put the food back down.

What if I miss a dose of Comfortis?

Give your pet his or her regular dose immediately, then resume a regular monthly schedule. To help you remember to dose your pet, sign up for monthly email or text messaging reminders. For complete safety information, view the Comfortis label.

What if I give more than the prescribed amount of Comfortis to my pet?

Contact your veterinarian if you believe your pet has ingested more than the recommended dose of Comfortis. Visit the Dosing & Administration page for more details, or see the Comfortis label for complete safety information.

Should I restrict my pet's activity or contact with my pet after the tablet is consumed?

No. You can continue normal activities and interactions with your pet.

Can other medications be given while my pet is taking Comfortis?

Comfortis is not contraindicated for use with any veterinary drug/product when they are administered at labeled doses. However, while labeled heartworm preventatives are not an issue, you should not use Comfortis concurrently with extra-label doses of ivermectin in dogs. Make sure your veterinarian is aware of all products that you intend to administer to your pet. In well-controlled field studies, Comfortis chewable tablets were administered safely in conjunction with other frequently used labeled products, such as vaccines, anthelmintics, antiparasitics, antibiotics, steroids, tick control products, anesthetics, NSAIDs, antihistamines, alternative/herbal remedies, shampoos, prescription diets, and most generally prescribed medications.

What should I discuss with my veterinarian regarding Comfortisfor my dog?

Your veterinarian is your pet's healthcare expert and can make the best medication recommendations. This includes the prevention, control and/or treatment of parasites such as fleas, heartworms and intestinal parasites. These parasites can cause conditions including flea allergy dermatitis, anemia and heart disease. Key points of your discussion might include:

  • The best time to start flea treatment in your geographic region.
  • What administration method will work best for your pet.
  • What to do if you miss a dose of Comfortis.
  • What other medications you give your pet.
  • What to do about a severe flea infestation.
  • What steps you can take to prevent a flea re-infestation in your home.
Rating: 4.9 of 5 stars 26 Reviews 26 Reviews 4.9 out of 5 Stars

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Rating: 4.9 of 5 stars 4.9 / 5

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26 Reviews

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  • 4 out of 5 stars

    Oops I messed up

    By Jello on Apr 21, 2021

    I got this hoping it did all 3(flea,tick,Heartworm) my mistake. And my pup is 132 lbs so I didn’t get enough meds. This works great for my sister-but I need to pay more attention

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  • 5 out of 5 stars

    Flea meds.

    By Iyab on Sep 19, 2020

    I was able to purchase my dog’s flea medication for the first time through Chewy. I was able to get a discount, for which I was very grateful. I received a call from Chewy, letting me know they were still working on contacting my dog’s vet. I really did appreciate them calling to let me know. The vet doesn’t even do that for their patients! I will keep ordering from Chewy from now on.

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  • 5 out of 5 stars

    Works like a charm

    By Amandavega on Sep 8, 2020

    We have tried many flea products trying to get rid of a bad flea infestation after we fostered puppies. This is the only thing that worked. It took a few weeks to actually get these with the prescription process, but all the dogs are are not itching anymore. Fleas are gone after one treatment so far.

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  • 5 out of 5 stars

    BEST Flea Med Ever

    By Kate on Sep 8, 2020

    I've had dogs for 20+ years and Comfortis has been the ONLY medication that works fast and well! I have never had an issue with my dogs taking it either. Highly recommend!

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  • 5 out of 5 stars

    Works for us

    By Exception on Jul 30, 2020

    We use this product with a prescription and send it through Chewy for the price. It works for our puppy and is better than a lot of other brands and you only have to give it with food once a month.

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  • 5 out of 5 stars

    One tablet last months, even years.

    By Paul on Apr 15, 2020

    I have three dogs. If I treat all three at the same time with Comfortis, it rids not only my dogs of fleas, but my house as well. I'm not sure how that works, but it does. While described as a monthly treatment, I find that unnecessary. I just wait until I see fleas again. I had to treat them this week; but before that, my last treatment was so long ago that I don't remember it. It's been literally years.

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  • 5 out of 5 stars

    Good stuff

    By Frankie on Mar 25, 2020

    My monster dog has allergies. Even after adjusting food, shampoos, you name it, she was pulling her hair out and scratching endlessly. Comfortis is the only medication that has stopped the itching. Her coat is shiny, bright and she has quit pulling at herself, rolling constantly. It's a relief to me that she feels relief.

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  • 5 out of 5 stars

    Works Great

    By Lacie on Apr 29, 2020

    Absolutely works great! Having it shipped is the best thing ever!

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  • 5 out of 5 stars

    This has worked

    By MrBeck on Sep 23, 2019

    Fleas are an issue this year, never prior. I tried every natural product which would more than likely work if it wasn't a horrendously bad year of flea explosion. I'm extremely hesitant to use anything chemical but had to give in and after researching decided Comfortis would do the least harm to the dogs. Ticks have not been a problem so I couldn't see also adding that chemical into their bodies.

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  • 5 out of 5 stars

    Easy Prescription

    By MitzisMom on Sep 4, 2019

    I needed to get a new prescription of Comfortis for my dog, which had to be approved by her vet. Chewy helped with this and within a few days the Comfortis arrived on my doorstep. So easy!!

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