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Best Flea Medicine for Dogs: Vet-Approved Options

Flea medicine for dogs main image of dog getting topical flea treatment
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Fleas can cause serious illness, transmit infectious diseases, and be a source of major discomfort. So, choosing flea medicine for dogs with optimal protection is a pretty big deal. 

Whether your dog already has fleas or you want to prevent them, we have the scoop on the most effective formulas—both prescription and over the counter—approved by veterinarians.  

The Importance of Flea Medicine for Dogs

Dog smiling outside with ears pointed up

Flea bites not only cause itchiness and skin irritation, they can result in serious illness, says Dr. Jerry Klein, chief veterinary officer for the American Kennel Club, based in New York City. “In tiny puppies and kittens, fleas can cause a life-threatening anemia due to significant loss of blood,” he says. “In many cases, flea bites can cause severe allergic reactions in both pets and people due to reactions to their saliva.” 

Fleas can transmit infectious diseases. “The most common flea of North America can transmit diseases like typhus, flea-borne spotted fever, bartonellosis (AKA cat-scratch disease), and flea tapeworms,” Klein adds.

Preventing flea infestations, veterinarians say, is much easier and more cost-effective than treating them. “The longer an infestation goes without treatment, the more environmental contamination will occur which can make resolving the infestation more difficult,” says Dr. Ashley Barnes, medical director at Louisville Family Animal Hospital in Louisville, Colorado. “It also increases the time the pet will be uncomfortable and increases risk for secondary skin infections.”

Another benefit of using a flea preventative, veterinarians say, is that they usually offer protection against ticks that can transmit diseases like Lyme disease, Rocky Mountain spotted fever, and rickettsiosis. Some products even protect against heartworms, mites, mosquitos, and other parasites.

Types of Flea Medicine for Dogs

Dog getting flea medicine via topical treatment

Most flea medicine for dogs is available in oral form (as chews and pills) and as topicals (including sprays), collars, and shampoos. They range in cost, effectiveness, and levels of protection.

Oral Flea Medicine for Dogs

Oral flea medicine for dogs comes as flavored chews that your dog enjoys every one to three months. With some exceptions, oral medicine is typically available only with a prescription.

Some flea chews for dogs protect against fleas and ticks, while others offer broader coverage. Simparica Trio—available with a veterinarian’s prescription—for example, also helps protect against heartworm disease, roundworms, and hookworms, as well fleas and ticks.

Capstar—a tablet that is available without a prescription—only targets fleas and is only effective for a short time. Capstar kills fleas that are on your dog at the time you administer the tablet, but it doesn’t have the long-lasting benefits of other flea preventatives. (It only kills adult fleas as opposed to other oral products that have growth regulators, in addition to adulticides.) “In really bad infestations, we will sometimes use Capstar along with a preventative so we kill the fleas faster but prevent reinfestation,” says Barnes. 

Dog with chew that is flea medicine for dogs

Other oral flea preventatives remain in your dog’s system for one to three months, offering continued protection. Oral products are the most effective form of flea medicine for dogs, veterinarians say. They’re a good option if your dog doesn’t do well with collars, or you don’t want your children or other pets exposed to topical flea medicine ingredients.   

Oral flea medicine for dogs is generally more expensive than other products, and they don’t offer repellent activity, says Dr. Susan Jeffrey, an associate veterinarian at Odyssey Veterinary Care in Fitchburg, Wisconsin. “The flea has to bite the pet in order to ingest the medication.”

Chewable flea prevention may not be a good fit for dogs with food sensitivities or conditions like irritable bowel disease, says Klein. Additionally, “These products should be cautioned in pets with pre-existing epilepsy,” says Dr. Katie Pagan, a partner veterinarian with Heart + Paw in Fells Point, Maryland.  

Topical Flea Protection

Dog getting topical flea medicine treatment

“Orals are more effective but the topicals are a close second,” says Barnes.

These products get applied to your dog’s skin, typically once per month. Some topical flea medicines for dogs, like Frontline Plus, are available over the counter, while others, like Revolution, require a prescription. They also vary in their levels of protection. Revolution, for example, protects against heartworms, as well as fleas and ticks; while Advantage only kills fleas. 

A plus is that many topicals have a repellent component in addition to ingredients that kill the fleas, says Jeffrey. 

Some people may not want their kids exposed to flea medicine, Jeffrey adds. Additionally, “Some of the topicals also have tick preventives that can be toxic to cats who could potentially come into contact with the medication.” 

Prescription topical medications are typically more effective, and non-prescription topicals vary in their effectiveness. “If I know someone who wants the cheapest medication, I try to steer them toward Frontline Plus or Advantage because they are over the counter and known to be safe and usually effective,” says Jeffrey.

Flea Collars

Dog wearing a flea collar as flea medicine for dog

Once a flea collar is fitted properly around the dog’s neck, it slowly distributes ingredients that kill fleas (and ticks, in some cases). Collars are available without a prescription and are more cost effective than chews or topicals. 

As with other over the counter flea products, effectiveness can vary. “A Seresto collar is very effective for dogs (and cats) but other collars out on the market just do not work well or can cause contact dermatitis to the skin,” says Pagan. The duration of protection varies by product, though Seresto’s collar lasts for 8 months.

Collars can offer protection, says Klein, but are not used as much as topicals, pills, and shampoos. 

Flea Shampoos

Dog having a bath with flea shampoo

Though most veterinarians recommend oral flea medicine, topicals, and collars for optimal protection, flea shampoos might be an option if you prefer a natural product. Keep in mind that shampoos don’t offer ongoing protection against fleas, however, says Pagan. “It only kills what is on them.” 

As with other non-prescription flea products, shampoos can vary in their effectiveness; and some dog shampoos can interfere with topical tick and flea medicines. Discuss using a flea shampoo with your veterinarian before bathing your dog with one of these products.

Best Flea Medicine for Dogs According to Veterinarians

To help take the guesswork out of choosing effective parasite protection, we’ve compiled a list of some of the best flea medicine for dogs that veterinarians approve of and recommend. 

Your own veterinarian can ultimately suggest a product that is best suited to your dog. If a product isn’t mentioned here, that doesn’t infer that it’s ineffective.

Best Fast-Acting Tick and Flea Medicine for Dogs

Our pick: Credelio

Credelio for Dogs

Credelio is a small, beef-flavored chewable tablet that kills ticks and fleas fast (in as little as four hours) and offers one full month of protection. It is effective against four types of ticks: lone star tick, American dog tick, black-legged tick, and brown dog tick. This medication is available by prescription, so talk to your veterinarian about whether it is a good fit for your dog. Some pet parents may choose to use this medication along with Interceptor Plus, which protects against all five major worms, for broad-spectrum parasite protection.


  • Beef-flavored chewable tablet given orally, once a month
  • Treats and prevents flea infestations and treats and controls tick infestations
  • Effective against four types of ticks
  • Protection lasts a full month
  • Available in a variety of strengths, according to a dog’s weight

Things to Consider

  • Must be administered with food or given within 30 minutes of feeding your dog
  • Cost varies depending on the strength of the dose and the number of doses in each box
  • Not suitable for puppies under 8 weeks of age 
  • Dogs must weigh 4.4 pounds or greater to use this medication
  • Potential side effects may include weight loss, elevated blood urea nitrogen, increased urination, and diarrhea. 
  • Use with caution in dogs with a history of seizures or neurologic disorders

Check out our full review

Best Flea Medicine for Dogs with Multi-Worm Protection

Our pick: Trifexis

Trifexis for Dogs

Trifexis is a beef-flavored tablet that not only protects dogs from fleas but also heartworm disease and three kinds of intestinal parasites: hookworms, roundworms, and whipworms. It’s easy to give like a treat and only needs to be dosed once a month. As with other heartworm medications, your dog will need to be tested for an existing heartworm infection before starting this product. Talk to your veterinarian to see if Trifexis is a good fit for your canine companion.


  • Monthly, beef-flavored tablet given orally
  • Kills fleas on dogs and prevents infestations, prevents heartworm disease, and treats and controls hookworm, roundworm, and whipworm infections
  • Full month of protection
  • Available in a variety of  strengths, according to a dog’s weight

Things to Consider

  • Your dog will need to be tested for an existing heartworm infection before starting this medication 
  • Administer with food for maximum effectiveness
  • Cost varies depending on the strength of the dose and the number of doses in each box
  • Not suitable for puppies under 8 weeks of age
  • Dogs must weigh 5 pounds or more to use this medication
  • Potential side effects may include vomiting, decreased activity, itching, decreased appetite, and diarrhea
  • If vomiting occurs within one hour of administration, you will need to redose
  • Use with caution in dogs with pre-existing epilepsy

Check out our full review

Best Vet-Recommended Flea Medicine for Dogs

Our Pick: Simparica Trio

Simparica Trio Chewable Tablets for Dogs

Veterinarians recommend Simparica Trio because of its effective protection against ticks and fleas, as well as heartworms, roundworms, and hookworms—all in one convenient monthly chew. It’s a small, liver-flavored chewable tablet available by prescription. Because it provides heartworm protection, your dog will need a negative heartworm test on file in order to be prescribed this product. 

“I personally give this product to my dog along with hundreds of thousands of other dogs and have never had an issue,” says Pagan. 


  • Multi-purpose chew that kills fleas and prevents infestations, kills five types of ticks (including the Lyme-carrying Blacklegged tick), treats and controls roundworms and hookworms, and helps prevent heartworm disease
  • Liver-flavored chew that can be taken with or without food

Things to Consider

  • The cost for a six-month supply (six tablets) is on average, between $140 to $170 dollars, depending on the size of your dog
  • You can only get Simparica chewables with a prescription from your veterinarian. And because it contains a heartworm preventative, your dog needs a negative heartworm test on file
  • As with any oral flea medication, the flea has to bite the dog in order to ingest the medicine
  • May not be a good option for dogs with food sensitivities or epilepsy

Best Chewable Flea Medicine for Dogs

Our Pick: Bravecto

Bravecto Chews

While most flea medications are administered monthly, Bravecto chews provide protection against fleas and ticks for 3 full months. This makes it a convenient option for busy pet parents who might forget to administer a dose every month. Bravecto chews are available by prescription only.


  • Provides flea and tick protection for 3 months 
  • Works within hours after it’s been consumed

Things to Consider

  • Requires a prescription from your veterinarian
  • Oral flea medicine for dogs may not be a good fit if your dog has epilepsy or food sensitivities
  • Though one chew lasts for up to three months, it costs between $57 and $60.

Best Topical Flea Medicine for Dogs

Our Pick: Revolution

Revolution topical flea medicine for dogs

Revolution is a multi-use, FDA-approved topical solution—available with prescription—that you apply directly to your dog’s skin every 30 days. It protects against fleas (and prevents infestations), the American dog tick, heartworms, ear mites, and sarcoptic mange.

“I personally have prescribed this countless times. It is very safe and effective,” says Pagan.


  • Multi-spectrum product that protects against fleas, ticks, heartworms, ear mites, and mange
  • Good option for dogs who won’t eat chews or tolerate collars
  • Non-greasy, quick-drying formula. You can bathe your dog two hours after application without it affecting the ingredients

Things to Consider

  • Requires a prescription from your veterinarian, as well as a negative heartworm test
  • May not be a good option if you’re concerned about children or pets being exposed to flea medicine ingredients

Best Flea Medicine for Large Dogs

Our Pick: NexGard

NexGard Chewables

This beef-flavored chew kills adult fleas and ticks for one month. It’s FDA-approved to help prevent Lyme infections caused by Blacklegged ticks. 


  • Kills fleas before they can lay eggs. FDA-approved to prevent Lyme infections from Blacklegged ticks
  • Offers formulations specifically for large dogs, including those weighing between 60 and 121 pounds 
  • Comes in a tasty beef-flavored chew that can be taken without food

Things to Consider

  • Requires a prescription from your veterinarian
  • Chewable flea and tick medicine for dogs should be used with caution in epileptic dogs. It may also not be well tolerated in dogs with food allergies or sensitive stomachs
  • The flea has to bite the dog in order for the medicine to be effective

Best Flea Medicine for Small Dogs

Our Pick: Simparica


A bite-sized flavored chew that offers protection for 35 days and is available with a prescription. It protects dogs from flea infestations and ticks, including the Blacklegged species. Another plus is that Simparica doesn’t need to be given with food. 


  • Kills adult fleas, prevents infestations, and kills ticks that carry Lyme disease
  • Comes in formulations for small dogs, including those weighing between 2.8 and 5.5 pounds
  • Can be given without food

Things to Consider

  • Requires a prescription

Best Flea Medicine for Puppies

Our Pick: Revolution Topical Solution for Puppies

Revolution Topical Solution for Kittens & Puppies, under 5 lbs

Formulated for tiny bodies under 5 pounds, this solution gets applied to your puppy’s skin monthly. It’s a prescription-only, multi-use product that kills adult fleas and prevents infestations, prevents heartworm disease, and treats and controls ear mites. It’s fast-drying, so you can bathe your dog two hours after application without reducing the medicine’s effectiveness. 


  • Formulated for puppies under 5 pounds
  • Multi-use product that kills adult fleas, prevents infestations, prevents heartworm disease, and treats ear mites
  • Non-greasy formula that dries quickly 

Things to Consider

  • Requires a prescription and heartworm test on file

Dog Flea Medicine Buying Guide

Cost and convenience are, of course, important considerations when choosing a flea medicine. Other factors like your dog’s medical history and size, as well as product reliability, are critical to consider, too. 

What to Do When Purchasing a Flea Medicine

Dog scratching outside because has fleas

Consider your dog’s medical history. Pagan says caution should be used if considering chewable tablets for dogs with epilepsy. If your dog has a sensitive stomach, she says you may want a collar or topical instead of a pill. “If your dog is itchy and has sensitive skin a chewable tablet would be better suited for your needs. If you bathe your pet often and do not like a greasy product applied to the coat, a chewable tablet is for you and your pet.”  

Be careful with cats in the home. If you also share your home with cats, avoid flea and tick medicine for dogs containing permethrin, an ingredient in many tick preventives that is toxic to cats, says Jeffrey. “Since most flea preventives have a tick preventative, I avoid this ingredient if there is a cat in the house that could be exposed.”

Make sure to reach the label closely. When purchasing flea medicine without a prescription, it’s imperative to read the label—including whether the product is appropriate for your dog’s weight and age, says Klein. “Many medications are not label approved for puppies less than seven weeks of age, breeding, pregnant or nursing dogs.” 

Prescription Vs. Over the Counter Flea Medicine for Dogs

Dog yawning while getting topical flea medicine

Though veterinarians will recommend specific over the counter flea products if cost is a factor, they say prescription flea medicine for dogs is better regulated. Prescription products tend to be more effective, and associated with fewer side effects. 

Over-the-counter flea medicines may be less expensive and available without a prescription, but effectiveness can vary. “You always want to ensure you are purchasing any OTC products through a reputable party as there are many counterfeit products out on the market,” says Pagan.

Dog Flea Prevention vs. Treatment

Prevention is when you give your dog flea medicine on a regular basis to prevent infestations, says Jeffrey, “But it can also mean the product has ingredients that will repel fleas.” Treatment, she says, is when you use a product to kill fleas already known to be present on your dog. 

Most products currently on the market target both prevention and treatment, says Pagan. “They start killing fleas within hours and prevent them after the fact. Some pets may develop flea allergy dermatitis or parasites secondary to fleas so additional medications could be needed.” 

Where to Buy Flea Medicine for Dogs

Purchasing flea medicine through your veterinarian is the safest option. “Your veterinarian purchases products directly through a reputable party to ensure these products are not counterfeit and will not cause an issue with your pet,” says Pagan. 

If you’d rather purchase your flea medicine independently, start by asking your veterinarian for recommendations of trusted retailers. Or stick with trusted pet supply shops or online pharmacies. These services will often contact your veterinarian directly to ensure your prescription is on file and will ship the medication directly to your door. 

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