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Oral Flea Medicine for Cats: 4 Vet-Prescribed Choices

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For some pet parents, fleas may seem like more of a nuisance than a threat. But if you’re tempted to pooh-pooh this puny parasite, think again. Though small, fleas can become a big problem for you and your kitty if you’re not using the proper topical or oral flea medicine for cats. And once fleas stake a claim on your pet, they can be very difficult to eliminate

“All you need are a couple of adult fleas to establish an infestation,” says Dr. Bruce Kornreich, DVM, Director of the Cornell Feline Health Center in Ithaca, New York. “They can come in on people, on other pets, or through walls and other entryways.”

Veterinarians often recommend oral flea medication as the most effective option to help protect pets from fleas.[1] However, if you find the prospect of persuading your feisty feline to comply with monthly flea pills a bit daunting, take heart. Here’s everything you need to know about the best oral flea medicine for cats, including picks you can discuss with your vet.

Flea Medicine for Cats: Why it’s Important

Just hearing the word “flea” is enough to start some pet parents scratching imaginary flea bites. While it’s true that these pesky parasites are best known (and feared) for their itchy bite, Dr. Kornreich says your cat’s itchy skin may be the least of your worries. 

The more serious threat is that some fleas carry diseases that they can pass along to your pet.  “Once your cat has been infected with a disease from a flea, these can be easily transferred to other cats or humans in the home,” Dr. Kornreich explains.

Some flea-borne diseases are transmitted when a flea bites a host, passing along bacteria like Bartonella henselae, which can cause cat scratch fever in humans. Other threats, like tapeworm larvae, can be transmitted when your cat ingests an infected flea — for example, while grooming. 

Additionally, Dr. Kornreich says cats can develop anemia from flea bites, as well as flea allergy dermatitis — an allergic reaction to flea saliva that makes it especially difficult and uncomfortable to deal with their presence. 

Flea medication for cats can help keep these health threats at bay, and there are plenty of options on the market to consider. That’s why it’s important to consult with your veterinarian to find the best cat flea medicine to fit your pet’s needs.  

Cat Flea Treatment: Topical vs. Oral Cat Flea Medicine 

First, it’s important to understand the differences between oral cat flea medications and other ways of administering flea medicine to cats — specifically topical treatments.

Dr. Kornreich says the primary difference is that topical flea medications can be easily applied to your cat’s skin, where they typically kill fleas on contact.  By contrast, oral medications work from the inside out — meaning fleas must bite your cat to be eradicated. 

While choosing the option that spares your cat more flea bites may seem to make the most sense, Dr. Kornreich says there are other factors to consider. 

For example, applying topicals may be easier, but it can also be messy and inexact. Also, Dr. Kornreich says topical flea medications can be hazardous if ingested, making them a poor choice for homes with small children or other pets who may touch or lick your cat’s fur. 

The best oral flea medications kill fleas faster and more efficiently than topicals can, some in as little as 30 minutes. And because these flea medications work internally, they don’t pose a risk to other pets or members of your family. Oral flea treatments are also a good choice for cats with flea allergy dermatitis, whose skin may get irritated by topical flea solutions. 

Then there are the stats: Research published in Veterinary Parasitology showed that oral flea treatments (spinosad) were 99.9 percent effective in a 90-day study of dogs, compared to topical treatments (fipronil/(S)-methoprene), which were only 88.4 percent effective.

Top Oral Flea Meds for Cats

All featured products are chosen at the discretion of the Great Pet Care editorial team and do not reflect a direct endorsement by the author.

  • Best Overall Oral Flea Medication for Cats: Credelio
  • Best Fast-Acting Flea Medication for Cats: Comfortis
  • Best Over-the-Counter Oral Flea Treatment for Cats: Capstar
  • Best Value Oral Flea Treatment for Cats: CAPACTION

Best Flea Medicine for Cats: 4 Vet-Approved Picks

It’s important to work closely with your veterinarian to determine the best oral flea medicine for your cat’s needs. Your vet will consider factors such as the severity of the infestation, other parasite threats in your area, whether pills or chewables would work better for your cat, and your pet’s age and weight, as some products are not safe for kittens or very young adults.

Here’s some helpful info about the top vet-prescribed oral flea medications for cats, so you can have an informed conversation with your vet about the best option for your cat. 

Best Overall Oral Flea Medication for Cats

Our Pick: Credelio

Credelio for cats ranks highest on the list because this monthly preventative offers pet parents everything you could ask for in an oral flea medication for your pet. (And then some!) It’s the first and only chewable tablet preventative that helps kill and control fleas and black legged ticks (Ixodes scapularis) which can transmit Lyme disease. 

And it comes in a yummy vanilla-flavored tablet designed to please even the most finicky felines. Just administer the chewable tablet once a month and the medication begins killing fleas within six hours. According to the manufacturer, Credelio kills 98 percent of fleas within 12 hours and is 100 percent effective within 24 hours. 

Credelio chewable tablets for cats can be given to kittens as young as eight weeks and more than two pounds for effective flea treatment. One important thing to note is that Credelio contains a class of drug (isoxazoline), which is not recommended for pets with a history of seizures or neurologic disorders. So make sure to work closely with your vet to ensure this oral flea and tick chewable is right for your pet. 


  • First and only chewable flea and tick preventative for cats
  • Fast-acting and highly effective
  • Made with vanilla and yeast flavor to encourage easy dosing
  • Also treats and controls deer ticks

Things to Consider: 

  • Must be given monthly, preferably with food
  • Provides flea protection for kittens 8 weeks and older, weighing 2 lbs or more
  • Provides tick protection for kittens 6 months and older, weighing 2 lbs or more 
  • Not recommended for cats with seizures

Best Fast-Acting Flea Medication for Cats

Our Pick: Comfortis

If your primary concern is fleas and you want them gone fast, then Comfortis is the flea preventative for you. 

Comfortis doesn’t come with all the bells and whistles of other multifunctional oral flea medications for cats. But it does have what many pet parents want most: speedy relief and effective protection against future flea infestations.

Comfortis is the first FDA-approved chewable flea preventative that starts killing fleas in 30 minutes. It comes in an appealing beef flavor for easy administration. Some pet parents report that it has a medicinal smell that their cats don’t especially enjoy, while others say their cats gobble it down without issue. Comfortis kills fleas before they can lay eggs and is effective for a full month. 


  • Starts killing adult fleas within 30 minutes
  • Effective for 30 days 
  • Beef-flavored chewable tablet is easy to administer 

Things to Consider: 

  • Must be given monthly, preferably with food
  • Provides flea protection for kittens 14 weeks and older, weighing 4.1 lbs or more
  • Does not kill or control any other parasites
  • Requires a veterinary prescription

Best Over-the-Counter Oral Flea Medication

Our Pick: Capstar

For pet parents who want a short-term, fast-acting treatment for an active flea infestation that doesn’t require a prescription, Capstar is the answer. This oral medication offers fast flea relief, killing adult fleas on your cat within 30 minutes. And it’s safe to use in kittens as young as 4 weeks old.

However, it’s important to note that Capstar is a flea treatment, not a flea preventative. Although powerful, its effects last 24-48 hours, meaning it’s really best for a quick burst of effectiveness in conjunction with a longer-lasting monthly preventative. 

Capstar tablets can be safely administered to your pet as often as once per day. However, if you’re not addressing the root cause of the infestation with a flea preventative, your pet will remain at risk. 

Capstar is also a tablet, not a chewable, which could make administering a little more difficult (though many pet parents reported crushing it and mixing it with food without much trouble).


  • Fast-acting flea treatment starts killing adult fleas within 30 minutes
  • Safe for very young kittens 4 weeks and older, weighing over 2 lbs
  • Kills 90 percent of fleas within six hours
  • No prescription required

Things to Consider: 

  • Effective as a flea-killing treatment, but will not prevent re-infestation
  • Available only in non-chewable tablet

Best Value Oral Flea Treatment for Cats


Made with nitenpyram, the same active ingredient as Capstar, CAPACTION delivers the same fast-acting, flea-killing benefits at a price point that’s easier on your budget. You don’t need a prescription for this oral flea treatment, which comes in a non-chewable tablet form that starts to kill fleas within 30 minutes.

However, like other short-term treatments, CAPACTION only works on active flea infestations. While it’s a great budget option for cats who need a quick-acting burst of flea protection, it’s best to follow up with a flea preventative to avoid re-infestations from any existing flea eggs and larvae on your cat or in your home. 


  • Fast-acting, short-term flea treatment at a budget-friendly price
  • Safe for kittens 4 weeks and older, weighing over 2 lbs
  • Kills 90 percent of fleas within six hours
  • No prescription required

Things to Consider: 

  • Effective as a flea-killing treatment, but will not prevent re-infestation
  • Available only in tablet form, not as a chew

Cat Flea Medicine Buyer’s Guide

The safest and best way to ensure that you use the best cat flea medicine for your feline friend is simply working with your veterinarian. Your vet knows your cat’s medical history and the various pros and cons associated with each option available.

According to Dr. Kornreich, among the key factors your vet will consider are your cat’s age and weight and if they have a history of seizures or other health concerns. 

While over-the-counter options may be more convenient and appealing, keep in mind that short-term flea treatments are best when paired with longer-term flea preventatives.  

Oral Flea Meds for Cats: Tips for Success

Even the most compliant cats may not always be in the mood to take a monthly flea preventative. But ensuring your cat receives (and consumes!) the full dose of any oral flea medication is important. Otherwise, it’s all too easy for fleas to return with a vengeance. 

Always administer your cat’s oral flea medication per the manufacturer’s instructions. For example, Credelio chewable tablets should always be given with food or within 30 minutes after your cat eats. The presence of food ensures that the medication will be properly absorbed into your cat’s blood for peak efficacy. 

It’s important to remember, however, that most oral flea medicines can only kill adult fleas because those are the ones actively seeking blood meals, which is how they consume the compound that kills them, Dr. Kornreich says. 

“To truly get rid of fleas, you have to disrupt the life cycle, and that means dealing with the adults and the environment,” he says. In addition to killing the adult fleas on your pet, it’s important to rid your environment of eggs or larvae that have found a home but aren’t yet hungry adults. Even with this two-pronged approach, Dr. Kornreich says it may take time to truly get rid of the problem.

Additionally, giving your cat an oral flea medication may be challenging for a different reason: Many cats hate oral medications. If that describes your cat, consider options that come in a tasty chewable format. Or, try mixing the oral medication in with your cat’s food and give a very high-value reward afterward. 

But some cats just won’t do it, and you should discuss with your vet if a non-oral medication is right in those cases. The best flea preventative for your cat is the one you can administer safely and consistently!


Dryden, Michael  W., et al. “Assessment of Owner-Administered Monthly Treatments with Oral Spinosad or Topical Spot-on Fipronil/(s)-Methoprene in Controlling Fleas and Associated Pruritus in Dogs.” Veterinary Parasitology, Elsevier, 31 Jan. 2013. https://doi.org/10.1016/j.vetpar.2012.09.003