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Comfortis Chewable Tablets for Dogs and Cats Rx

Comfortis chewable tablets kill fleas and are indicated for the prevention and treatment of flea infestations (Ctenocephalides felis) on dogs and cats for one month. See Allivet's Flea and Tick chart to find which flea and tick product is best for your pet.

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What is Comfortis Chewable Tablets for Dogs and Cats?

COMFORTIS chewable tablets offers the same formula for cats & dogs, kills fleas and controls flea infestations (Ctenocephalides felis) for one month. This easy to administer tablet kills fleas within 30 minutes and provides protection against fleas for 30 days.

Who is Comfortis Chewable Tablets for Dogs and Cats for?

Comfortis is for Dogs, Puppies, Cats & Kittens (14 weeks or older)

Why use Comfortis Chewable Tablets for Dogs and Cats?

-Comfortis is easy to administer, no messy application
-Comfortis comes as a palatable Beef flavored tablet
-Comfortis starts killing fleas within 30 minutes
-Comfortis kills fleas before they can lay eggs
-Comfortis lasts 30 days, 1 month
-Comfortis won't wash off with bath
-Comfortis is environmentally friendly

How does Comfortis Chewable Tablets for Dogs and Cats work?

The primary ingredient in Comfortis is Spinosad which kills fleas by causing excitation of the insect’s nervous system, leading to paralysis and rapid death.

Generic Brands:



Elanco Animal Health

Active ingredient(s):

Active ingredient in Comfortis is Spinosad

How is Comfortis Chewable Tablets for Dogs and Cats sold?

Sold depending on your pets weight in 3 month, 6 month and 12 month supplies.

What are the side effects of Comfortis Chewable Tablets for Dogs and Cats?

The most common adverse reaction to Comfortis is vomiting.Other adverse reactions reported in decreasing order of frequency are: depression/lethargy, decreased appetite, incoordination, diarrhea, itching, trembling, excessive salivation, seizures or death.

What special precautions are there?

Do not give Comfortis to dogs or kittens younger than 14 weeks of age.

What to do if overdose?

Contact your nearest emergency animal hospital.

How can I store Comfortis Chewable Tablets for Dogs and Cats?

Use with caution in breeding females (see). Use with caution in dogs with pre-existing epilepsy (see ADVERSE REACTIONS. The safe use of Comfortis chewable tablets in breeding males has not been evaluated.

Helpful Tips:

Treatment with Comfortis chewable tablets may begin at any time of the year, preferably starting one month before fleas become active and continuing monthly through the end of flea season. In areas where fleas are common year-round, monthly treatment with Comfortis chewable tablets should continue the entire year without interruption.

Pharmacists are standing by to offer Pet Parent counseling regarding prescription medication purchased from Allivet before and after dispensing. Pharmacists on duty are available Monday-Friday, 9:30AM - 5:30PM EST and will be on call Saturday 12:00PM - 4:00PM EST for consultation.

Dosage Schedule: Cats over 24 lbs should be administered the appropriate combination of tablets.

Comfortis Chewable Tablets Cats

Body Weight

Spinosad Per Tablet


2 to 4 lbs

90 mg

1 Tab 

4.1 to 6 lbs

140 mg

1 Tab 

6.1 to 12 lbs

270 mg

1 Tab 

12.1 to 24 lbs

560 mg

1 Tab 

 Dosage Schedule: Dogs over 120 lbs should be administered the appropriate combination of tablets. 

Comfortis Chewable Tablets Dogs

Body Weight

Spinosad Per Tablet


3.3 - 4.9

90 mg

1 Tab 

5 to 10 lbs

140 mg

1 Tab

10.1 to 20 lbs

270 mg

1 Tab 

20.1 to 40 lbs

560 mg

1 Tab 

40.1 to 60 lbs

810 mg

1 Tab 

60.1 to 120 lbs
1620 mg
1 Tab 

Most pet owners have faced the challenge of ridding their homes and pets of fleas. Fleas can be a problem because they reproduce so rapidly. The persistent parasite can cause discomfort for cats, dogs and their owners. Understanding Fleas makes it easier to treat what could become a major infestation problem. 
What are Fleas?
-Fleas are external pests that are capable of fast reproduction, by surviving on your pet’s blood. These tiny insects are brown in color. Although they are wingless they are able to jump reaching incredible heights. Their bodies are compressed, or flattened, from side to side. Their size make them hard to detect and much more difficult to eliminate from your pet or home. A single female flea may produce up to 2,000 eggs over her lifetime. Eggs hatch and can develop into adults within only three weeks. Adult female fleas feed by ingesting blood from your pet and subsequently lay eggs, which drop off your pet’s coat. Within days, larvae hatch from the eggs and live undetected in your pet’s surroundings, such as the carpet, bedding and other protected areas. Flea larvae spin a cocoon, and, when appropriately stimulated, a young adult flea emerges and jumps onto your pet to continue the life cycle.




How does my pet become Flea Infested?

-The warm and dark environment of your pet’s fur and skin provide the perfect environment and feed for fleas.  A little time spent outdoors and pets easily become flea infested. Indoor cats are at risk even if they just go out on the patio. They are also at risk if they share their home with a dog or other cats.

Pets get fleas from other animals- a stray dog or cat, neighbor’s pet, or urban wildlife like opossums and raccoons may have passed through your yard while the female flea is laying eggs and the eggs are left in your pets environment. Those eggs then develop into adults and those fleas jump onto your pet.


Warning signs of Fleas


            Fleas on Dogs:

-Flea droppings (dark specks) in the fur.

-Flea eggs (white specks) in the fur.

-Excessive licking or scratching.

-Scabs or hot spots on the skin.

-Allergic dermatis

-Hair loss

-Pale Gums



               Fleas on Cats:

The easiest way to find fleas on a cat is to check the belly. You may see the fleas or small dark spots that move if they do not move it is possible you are viewing their droppings, which look like specks of dirt. Excessive scratching and hair loss are also signs that fleas may be feasting on your feline.

Disease Transmitted by Flea bites
Since fleas can consume 15 times their own body weight in blood, they can cause anemia or a significant amount of blood loss over time. This is especially problematic in young puppies, where an inadequate number of red blood cells can be life-threatening to some dogs. Signs of parasitic anemia include pale gums, cold body temperature and listlessness.

When a cat or dog has a heightened sensitivity to the saliva of fleas, just one bite of a flea can cause an allergic reaction. This condition is known as flea allergy dermatitis and causes intense itching and discomfort for your cat or dog.  Signs include generalized hair loss, reddened skin, scabs and hot spots. Flea allergy dermatitis often leads to skin infections.


Getting rid of fleas is where the battle begins and ends once you have protected your pet from reoccurring infestation.
1) Flea shampoos are successful at ridding your pet of adult fleas. Bathing your pet with flea shampoo will be their first source of relief from biting fleas. Follow the directions carefully. Most shampoos require you to leave the lather on your pet for 10 minutes. Check his fur CAREFULLY while bathing.  Try to remove ALL of the fleas you find. Shampoos that kill the flea, rather than just remove them, are more successful. Start at your pets head and work your way down.  Fleas will instinctively move to higher ground. If you start at the head you have better control of the pests and are more able to keep tabs on how well you have eradicated the fleas.  Continue by working your way from the head towards the back and the chest. 
2) Treats  flea infestations in dogs, puppies, cats and kittens 2lbs of body weight or greater. Capstar stops fleas from biting and kills adult fleas within 30 minutes. This is a great choice for treating outbreaks because it can be used with other flea prevention and if you still find fleas on your pet, you can administer another dose the following day.
3) Treating your yard and area is an important step to treating infestations. You may rid your pets of fleas but if you do not treat the area, they will be re-infested. A treatment that kills fleas and the larvae is most efficient. 



Successful flea control must include a flea treatment that will stop the flea “cycle”. This cycle includes all life stages of the flea, the eggs, larva, pupa and adult stage.
1)   Flea Collars:  Moderately effective at keeping fleas off your pet and providing an unhealthy, un-welcoming environment in your pet’s fur.
This is the first line of defense.  A few carefully placed drops between the shoulder blades (to keep your pet from ingesting it) will protect your cat or dog for up to a month. 
3) Oral Flea Prevention: Oral flea prevention is often administered once a month orally. These products are noted for causing the larvae to become unable to reproduce, thus rendering an end to the life cycle. 
4) Natural Solutions: If you prefer a non-chemical solution, natural remedies are also available to protect your pet from fleas.






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