How Long Does Comfortis Last?

how long does comfortis last
Discover how long does Comfortis last and keep your furry friend protected from fleas all year round.

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Comfortis is a popular flea and tick medication for dogs that provides fast-acting and long-lasting protection against these pesky parasites. If you’re considering using Comfortis for your furry friend, you may be wondering, “How long does Comfortis last?”

In this article, we will explore the duration of effectiveness of Comfortis and provide you with all the information you need to make an informed decision for your pet’s health and well-being.

What is Comfortis?

Before we dive into the duration of Comfortis’s effectiveness, let’s first understand what Comfortis is and how it works. Comfortis is an oral flea and tick medication specifically designed for dogs. It contains the active ingredient spinosad, which kills fleas and ticks by targeting their nervous system. When your dog ingests Comfortis, it circulates in their bloodstream and starts working within 30 minutes to kill fleas and ticks that bite your pet.

How Does Comfortis Work?

Comfortis works by targeting the nervous system of fleas and ticks. The active ingredient, spinosad, binds to specific receptors in the insects’ nerve cells, causing them to become hyperexcited and leading to paralysis and death.

This mechanism of action ensures that Comfortis not only kills adult fleas and ticks but also prevents their eggs from hatching, effectively breaking the flea life cycle.

How Long Does Comfortis Last?

Now let’s get to the main question: how long does Comfortis last? Comfortis provides protection against fleas for a full month. After your dog ingests Comfortis, it starts working within 30 minutes and continues killing fleas for the next 30 days.

This means that your furry friend will remain flea-free for a whole month, providing them with much-needed relief from itching and discomfort.

Is Comfortis Effective Against Ticks?

While Comfortis is primarily known for its effectiveness against fleas, it also provides some protection against ticks. However, it’s important to note that Comfortis is not as effective against ticks as it is against fleas.

While it may kill some ticks that bite your dog, it does not repel ticks or provide long-lasting tick control. Therefore, if tick prevention is a top priority for your dog, it’s advisable to use additional tick prevention methods in conjunction with Comfortis.

How to Administer Comfortis?

Administering Comfortis to your dog is a simple process. It comes in a chewable tablet form that is highly palatable, making it easy to administer orally. You can give Comfortis to your dog with or without food, although some dogs may experience mild gastrointestinal upset if given on an empty stomach.

It’s important to follow the dosage instructions provided by your veterinarian to ensure your dog receives the correct amount of medication based on their weight.

Are There any Side Effects of Comfortis?

As with any medication, there is a possibility of side effects when using Comfortis. The most commonly reported side effects include vomiting, diarrhea, lethargy, decreased appetite, and itching. These side effects are usually mild and transient, resolving on their own without any intervention.

However, if your dog experiences severe or prolonged side effects, it’s important to contact your veterinarian for further guidance.


In conclusion, Comfortis is a highly effective flea and tick medication for dogs that provides fast-acting and long-lasting protection against these pesky parasites. It starts working within 30 minutes and continues killing fleas for a full month, providing your furry friend with relief from itching and discomfort.

While Comfortis also offers some protection against ticks, additional tick prevention methods may be necessary for optimal tick control. By following the dosage instructions and monitoring for any potential side effects, you can ensure the safety and well-being of your pet while using Comfortis.

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