Safety

Comfortis has demonstrated to be safe in healthy dogs and cats when used according to label directions. Use only for cats and kittens 14 weeks of age or older and 4.1 pounds of body weight or greater, and for dogs and puppies 14 weeks of age and older and 5.0 pounds of body weight or greater. The safe use of Comfortis in breeding, pregnant or lactating cats and dogs has not been evaluated.

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.

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

For cats: In some cases, cats vomited after receiving Comfortis. If vomiting occurs within one hour of administration, redose with another full dose. Additional adverse reactions observed in studies were lethargy, decreased appetite, weight loss, and diarrhea. Use with caution with concomitant extra label use of ivermectin. See the Comfortis label for complete safety information.

For dogs: 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.