
Comfortis is a veterinary-prescribed, chewable tablet for dogs and cats used to treat and prevent flea infestations for one month. Its active ingredient, spinosad, starts killing fleas within 30 minutes of administration.
Spinosad
Comfortis® is a commercial brand of spinosad, a chewable insecticide utilized in veterinary medicine for the management of flea infestations. This prescription medication is formulated for use in dogs and cats, particularly when veterinarians seek an oral option for the management of active parasite challenges, with onset timing your veterinarian will discuss. At a pharmacological level, spinosad acts by activating nicotinic acetylcholine receptors (nAChRs) and gamma-aminobutyric acid (GABA) receptors in the insect nervous system. This activation leads to involuntary muscle contractions, tremors and paralysis, resulting in disruption of the flea's nervous system function. Comfortis® is characterized by its ability to manage flea populations shortly after administration, providing a method for addressing the immediate comfort of the pet. Your veterinarian will determine the appropriateness of Comfortis® based on your pet’s weight, age and exposure risk.
The actions described here reflect the product's FDA-approved labeling; your veterinarian determines the appropriate use for your animal.
Prescription only. Use only under the direction of a licensed veterinarian. This information is not a substitute for veterinary diagnosis, prescribing or monitoring.
Commonly observed effects following the administration of Comfortis® include localized digestive changes such as vomiting, especially if the tablet is not given with food. Some pets may exhibit behavioral shifts including lethargy, decreased appetite or temporary coordination changes. Owners should monitor their pet for any unusual signs of digestive distress or energy shifts and contact their veterinarian promptly with any concerns regarding their pet’s response. This medication is typically used with extra caution or avoided in pets with a history of seizures or epilepsy. It is also carefully evaluated in breeding, pregnant or lactating animals. Significant interactions can occur if Comfortis® is administered concurrently with very high doses of ivermectin, so a complete history of all other medications and parasite preventatives is essential. Your veterinarian is the right person to provide guidance on the necessary frequency of use and the most commonly considered administration protocol to ensure the management approach remains suitable for your pet's needs.
Yes. Comfortis is a prescription parasite medication and can only be dispensed by a licensed pharmacy upon receipt of a valid authorization from a licensed veterinarian. Mixlab ensures all prescription requirements are met before any medication is shipped to your home.
Comfortis is a proprietary commercial chewable tablet. While Mixlab specializes in compounding many customized medications, Comfortis is typically dispensed in its original commercial format. Your veterinarian can discuss alternative parasite management options if your pet has specific administration needs.
Veterinarians often discuss that spinosad begins managing fleas within 30 minutes of administration. Its mechanism acts to rapidly may help address active flea populations on your pet, providing a method for addressing immediate infestation challenges.
Yes. Veterinarians recommend administering Comfortis with a meal to maximize its absorption and manage the risk of localized stomach upset or vomiting. Giving the chewable with food helps ensure your pet remains comfortable and the medication is commonly considered.




