Comfortis vs. Capstar : Comparison and Key Differences

The pet-med market is overcrowded with brands claiming to offer premium levels of pet care and protection.

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When it comes to choosing a flea treatment for your pet, you can’t be too careful. It’s important to have all the facts before administering any medication or treatment to your furry friends.

We compared Comfortis chewable flea treatment to Capstar flea tablets to see which the better choice is.

Which is Better Comfortis or Capstar for Dogs?

Comfortis and Capstar deliver their flea treatment via a chewable tablet. Each kill flea infestations within 30 minutes.

Vets have voiced concern, however over the Comfortis flea treatment. Its safety and validity are in question because the treatment is not safe for dogs who are not in prime health.

Dogs at risk of complications from Comfortis include young puppies, pregnant females, and seizure prone dogs. Vets and pet owners have reported vomiting in dogs shortly after administering Comfortis.

Though, Comfortis does list vomiting as a common side effect. Due to these concerns we recommend Capstar flea treatment over Comfortis.

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Which is Better Comfortis or Capstar for Cats?

Our recommendation changes when our we switch our focus to felines. Capstar is highly effective at treating adult fleas in cats but loses effectiveness after 24 hours.

Comfortis demonstrates a high efficacy rate in felines. Clinical trials show that Comfortis begins killing fleas in 30 minutes.

After 4 hours Comfortis is 98% effective. Comfortis is 100% effective the day after application.

Vets and owners report vomiting as a side effect of Comfortis. However, the same side effect is present with Capstar.

We recommend Comortis over Capstar for cats due to the higher efficacy rate in felines.

Our Review of Comfortis and Capstar

Capstar and Comfortis are jumpstart flea programs. These are the products you buy when you discover your dog or cat has fleas, and you need them gone fast.

Each is intended to quickly and effectively destroy flea infestations. They kill fleas in as little as 4 hours but are rarely effective after 24 hours.

Vets recommend switching to a long-term flea treatment to prevent re-infestation.

Also Read: Simparica vs. Frontline

Key Differences Between Comfortis and Capstar

Capstar and Comfortis are similar in more ways than they are not. However, they do include several key differences.

Method of Delivery

Capstar is an over-the-counter flea treatment. It’s intended for use in dogs and cats older than four weeks and weighing more than 2 pounds.

Your pet’s body weight determines the correct dosage of the treatment.  Each chewable tablet contains a single dose and is administered once per month.

Comfortis is a prescription flea treatment for use in dogs and cats. One dose of Comfortis kills fleas and prevents re-infestation for one month. Comfortis is administered via a chewable beef-flavored tablet.

Comfortis can be safely administered to dogs older than 14 weeks and weighing more than 5 pounds. It’s also safe for cats 14 weeks or older and weighing more than 4 pounds.


Comfortis chewable tablets for dogs (and cats) are available in 5 different packages. Each Comfortis package is differentiated by color and contains six treatments.

Each color indicates the dosage level of the tablets and the corresponding body weight of the intended pet.

In contrast to the five dosage and package options offered by Comfortis, Capstar is only available in two dosage levels, though each is differentiated by color.

Capstar Flea Tablets for Dogs & Cats, 2-25 lbs – Blue Package

Capstar Flea Tablets for Dogs over 25 lbs – Green Package


Comfortis is only available by veterinarian prescription. As a result, Comfortis is significantly more expensive than Capstar. Comfortis treatments will set you back approximately $75-$115 a package.

The price of Comfortis climbs even higher if you count the cost of the vet visit to get the prescription. Both Capstar packages can be purchased for less than $25 respectively.

Comfortis and Capstar Active Ingredients Comparison

There are a lot of different flea treatments on the market, but they all do essentially the same thing, rid your pet of fleas. However, the active ingredient used in each treatment can vary greatly.

The active ingredient of a flea treatment determines not only the effectiveness of the treatment but also dosage level, treatment longevity, application and possible side effects of the treatment.

Comfortis: Spinosad

The active ingredient in Comfortis is spinosad. Spinosad is developed from compounds derived from a naturally occurring soil bacterium and used around the world as a broad-spectrum insecticide.

Spinosad contains spinosyn A and spinosyn D which are used to control a wide variety of insects, including fleas.

Spinosad is absorbed into your pet’s bloodstream. Infesting fleas then consume your pets spinosad-laden blood and die.

Capstar: Nitenpyram

The active ingredient in Capstar is nitenpyram. Nitenpyram is a fast-acting, broad-spectrum insecticide with agriculture and veterinary applications.

Nitenpyram is a neurotoxin that paralyzes and kills fleas by blocking the signals from its brain to the rest of its body.

Similar to Comfortis, the nitenpyram contained in Capstar is absorbed into your pet’s bloodstream. Infesting fleas then ingest the nitenpyram by consuming your pet’s blood.

Which Treatment is the Best Priced?

Capstar is the better-priced flea treatment option. Capstar is available over-the-counter, without a prescription.

Comfortis can only be purchased with a valid veterinarian prescription, and is more than twice as expensive as Capstar.

Which Do We Recommend?

We can’t help but side with veterinarians who recommend Capstar Flea Tablets over Comfortis Tablets for Dogs & (Cats)  

One dose of Capstar kills all adult fleas within 30 minutes. The quick-relief it provides your pet is well worth the low-price tag. The treatment is lightning fast and comes in an easy-to-administer- tablet.

Our Capstar recommendation is based on four features that are absent from the Comfortis flea treatment.

First; Capstar is available without a prescription, which makes it easier to purchase and contributes to its low price tag.

Second; Because Capstar is available over-the-counter, it is significantly less expensive than Comfortis.

Three; Customers and veterinarians report far less vomiting after treatment with Capstar than with Comfortis.

The fourth and final reason we recommend Capstar is because it is safe for use on puppies, kittens, and pregnant pets.

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7 Treatment Application Tips

You don’t have to tell us how hard it can be to convince/ trick your pet into ingesting their medicine. Here are seven tips to make flea treatment application a little easier.

For Dogs:

  1. Vomiting is a common side effect in Capstar and Comfortis. We recommend monitoring your dog after administering the tablet to ensure they do not regurgitate treatment. If your dog does vomit up the treatment, we recommend waiting a short time before re-administering treatment.
  1. It can be exceptionally difficult to administer a flea treatment to hyper dogs. We recommend taking your hyper dog for a long walk or a session of vigorous playtime to tire them out.Tired puppies are more likely to consume their food without noticing the flea treatment.
  1. It is not at all uncommon for dogs to refuse Capstar and Comfortis chewable tablets. One way around a picky pet is to conceal the treatment in a piece of deli meat or a treat.Give your dog a treat, or a piece of meat that does not contain any treatment. Once they have ingested the first treat, try again with the treat containing the treatment.

For Cats:

  1. advises that the easiest way to administer a chewable treatment to a cat is to conceal it in their food and hope they don’t notice. However, cats are observant by nature and often eat around the treatment.

If your cat keeps finding the treatment in their food we recommend purchasing pill pockets, or pill paste. Each enables you to hide the pill in a way that is tastier and less obvious to your kitty.

  1. Cats are very good at observing humans, but they don’t like being observed themselves. Cats are more likely to consume all of their food, including any concealed treatment if they can’t see you watching them eat.
  1. If your cat won’t eat the treatment it’s time to administer the treatment orally. Before administering treatment to your cat, gather everything will need; treatment, pill gun, fluffy towel, a syringe full of water, courage.

Gather up your cat in the towel and use the pill gun to administer the treatment orally. Chase the treatment with the syringe of water, then treat your scratches with a disinfectant and Neosporin.

  1. The most important tip to remember when administering any medication to your cat is to remain calm. Cats can read your emotions better than you can. They are aware when you are nervous, which makes them nervous and more likely to refuse treatment.

Final Thoughts

It is essential to your pet’s comfort and well-being that they be free of flea infestation. Fleas are more than uncomfortable; they carry diseases that can endanger your pets life.

Unfortunately, it’s very easy for your dog to contract fleas. Fleas transfer hosts by jumping from one mammal carrier to another, including common rodents like mice, rats, and squirrels.

Simple exposure to an infected animal is enough for your dog to contract fleas. Your dog can also contract fleas by coming in contact with flea-infested furniture, bedding, and even clothing.

Buying the right flea treatment is the first step to protecting your pet. The best flea treatments combine ease of application with results.

Capstar chewable tablets are cheap, effective and available over the counter. Comfortis is available by prescription only and has a wider variety of treatment options.

Though Comfortis is slightly longer-lasting, Capstar starts working sooner and is safer to use on puppies and pregnant or nursing dogs.

We recommend consulting your veterinarian before administering any flea treatment, or medication to your pet, but we can’t help but recommend Capstar over Comfortis.

Have you tried Capstar or Comfortis on your pet? Do you disagree with our recommendation? Maybe you have a pet treatment tip that you would like to share. Let us know in the comments below.

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