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Description & Usage

Comfortis is a monthly chewable flea preventative that starts working in just 30 minutes to repel fleas for 30 days. Safe for use on dogs and cats, this beef-flavored chewable is irresistible. Taken orally, there is no residue left on your pet's fur or downtime where your pet needs to be kept away from children or other pets. Comfortis is FDA approved and provides the same protection as any topical treatment without any of the mess. Safe for use on cats and dogs, 14 weeks and up.

Precautions & Side Effects

The most common side effects in dogs is vomiting. Contact your veterinarian if your pet experiences lethargy, loss of appetite or any sudden change in behavior. Use with caution in breeding females. Use with caution in dogs with a history of epilepsy.



Comfortis is given once a month for continuous, year-round protection against flea infestations. Comfortis can be chewed or administered with food.


Store Comfortis at temperatures between 68° - 77°F.

Dosing Chart

Dogs and puppies (14 weeks or older)

Weight Dosage
5 to 10 lbs Give one 140mg chewable tablet every month
10.1 to 20 lbs Give one 270mg chewable tablet every month
20.1 to 40 lbs Give one 560mg chewable tablet every month
40.1 to 60 lbs Give one 810mg chewable tablet every month
60.1-120lbs Give one 1620mg chewable tablet every month
Over 120 lbs Give the appropriate combination of tablets







Cats and Kittens (14 weeks or older)

Weight Dosage
4.1 to 6 lbs Give one 140mg chewable tablet every month
6.1 to 12 lbs Give one 270mg chewable tablet every month
12.1 to 24 lbs Give one 560mg chewable tablet every month

What is Comfortis?

Comfortis (spinosad) is a monthly preventive treatment to kill and prevent fleas in dogs and cats (14 weeks or older). These beef-flavored chewable tablets are administered orally once a month for year-round protection against fleas. 

When should I start treatment with Comfortis?

You may begin treatment at any time of the year. It is recommended that you use Comfortis monthly for year-round protection. You should treat all pets in the household to prevent flea infestations or re-infestation.

How quickly does Comfortis kill fleas?

Comfortis chewable tablets (spinosad) kills fleas within 30 minutes and usually kills 100% of fleas on dogs and 98% of fleas within just 4 hours. It kills fleas before they can lay eggs and stays effective for one full month.

Can I give Comfortis to my dog or cat?

Comfortis has been shown to be safe for use in both dogs and cats 14 weeks or older. Please contact your veterinarian for breeding, pregnant or lactating cats/dogs.

Is Comfortis safe for my pet?

Yes, Comfortis is safe when used in healthy cats and dogs according to the label instructions and correct dosage. Some side-effects can occur. If vomiting occurs within one hour of administration, re-dose your pet with another full dose. Refer to the label for complete safety information.

How to give Comfortis (spinosad) to my pet?

Comfortis should be given as a full dose once a month. You can administer the beef-flavored chewable tablet orally prior or after feeding.

Can Comfortis be taken with other medications?

Comfortis (spinosad) is safe to use with other veterinary drug administered at labeled doses. Do not use Comfortis with extra-label doses of ivermectin in dogs. When in doubt, contact your veterinarian to make sure your pet can safely combine the use of medications.

What questions should I ask my veterinarian regarding Comfortis (spinosad)?

When it comes to your pet’s healthcare, your veterinarian knows best! Here are a few questions to ask:
• When are fleas most active in your area/sate
• What to do if you miss a dose of Comfortis
• How to properly treat a severe flea infestation
• How to properly prevent a flea infestation in your household