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Capstar for Dogs and Cats Review

By: Carl Laron on May 12, 2017

Bottom Line

Capstar for Dogs and Cats is an over-the-counter tablet that's very safe for both dogs and cats as young as four weeks and that weigh between 2 and 25 pounds. A version for dogs over 25 pounds is also available. Capstar kills fleas quickly and without the mess of topical treatments, but it works only on adult fleas.


  • Kills adult fleas quickly
  • Side effects are rare
  • No mess
  • No prescription required


  • Doesn't kill flea eggs or larvae
  • Pets may not take pill willingly
Our Analysis
Read Amazon Reviews

Breaking it down


Kills adult fleas only. Most reviewers, including vets and pet owners, say Capstar for Dogs and Cats works amazingly fast. Many users say they could literally see fleas dropping off their pets in an hour or less. However, others complain that it had no effect on their pets or that it wore off very quickly. Some of these owners may not have realized that Capstar kills only adult fleas and won't stop new ones from appearing. Some owners say they can keep fleas at bay just by repeating the dose of Capstar every week or so, but others use Capstar for immediate relief and a topical treatment for long-term control.


Safe for pets and humans. All reviewers agree that Capstar poses virtually no risk to humans. Side effects in pets are also less common, and less severe, than with topical treatments. A few owners note that pets (especially cats) may become hyperactive as the medicine takes effect, possibly because the fleas bite more as they die. Very rare side effects include lethargy, trembling and allergic reactions.

Ease of use

Can be tricky to administer. Some pet owners like the fact that this tablet doesn't create any mess like topical treatments do. Most users report no problems getting their pets to take Capstar, but a few say that some pets, especially cats, are reluctant to swallow it. Some owners say the easiest method is to put the pill in the pet's food or hide it in a treat such as cheese or peanut butter.

Our Sources

Contributors to Amazon.com, As of May 2017

We found more than 4,500 user reviews here for Capstar. Pet owners generally find this product safe and effective, giving it an overall rating of 4 stars. The most common complaint is that it kills adult fleas only and can't treat an infestation on its own.

Contributors to 1800PetMeds.com, As of May 2017

Nearly 650 pet owners review Capstar for Dogs and Cats at this online pet pharmacy. Users give Capstar a rating of 4.2 stars out of 5 overall, with 4.2 stars for effectiveness. Most owners say it works fast, with no adverse effects. Some note that re-infestations can occur; some deal with that by giving Capstar every one to two weeks, others by using Capstar to get rid of fleas immediately, and a monthly treatment such as Frontline for long term relief.

Staff of All Feline Hospital, Not Dated

Vets at All Feline Hospital in Lincoln, Neb., say Capstar for Dogs and Cats kills adult fleas within 30 minutes, making it great for fast relief in cats with flea allergies. However, it must be combined with topical treatments to completely eliminate fleas from the home.

Nancy Kerns, Sept. 16, 2016

In this blog post, Whole Dog Journal editor Nancy Kerns relates her own recent experience with a flea outbreak. Following the regimen that experts recommend, she uses Capstar in combination with a topical spot-on treatment. That, coupled with a thorough house cleaning, completely stopped "the flea riot." She follows up by putting Seresto collars on her dogs, and reports no further flea issues.

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