The Best Flea Medicine for Dogs

Fleas are an inevitable part of dog ownership. No matter where you are in the world, there are fleas that would happily take a bite out of your dogs if given a chance. Fleas aren’t just annoying for our furry friends; they can bite and terrorize us as well.

We reviewed dozens of products to identify the best of the best. We considered each product’s customer reviews, cost, effectiveness, safety, versatility, and availability when selecting each product.

Best Overall Flea Medicine for Dogs
Bayer K9 Advantix II Flea, Tick, and Mosquito Prevention for Large Dogs
For all-around great protection, this flea medication is suitable for most pets.

In the end, we concluded that Bayer K9 Advantix II Flea, Tick, and Mosquito Prevention for Large Dogs was the best option for most owners. This medication isn’t costly and is suitable for many different dog breeds. It protects from flea, ticks, and mosquitos, giving you all-around protection throughout much of the year. There are a few different dosage options available as well, so you can save a bit of money when you buy in bulk.

The 5 Top-Rated Flea Medicines for Dogs

Editor's PicksBrandRating
Best OverallBayer K9 Advantix II Flea, Tick, and Mosquito Prevention for Large Dogs4.3
Best Oral Flea Medicine for DogsCapAction Oral Flea Treatment Small Dog4.4
Best Budget BuyHertz Topical Flea & Tick Prevention3.8
Best Fast-Acting Flea Medicine for DogsCapstar Fast-Acting Oral Flea Treatment for Large Dogs4.0
Best Long-Lasting Flea Medicine for DogsPetArmor Plus for Dogs4.1

*Ratings are from Amazon at the time of publication and can change

Best Overall Flea Medicine for Dogs: Bayer K9 Advantix II Flea, Tick, and Mosquito Prevention for Large Dogs

Bayer K9 Advantix II Flea, Tick, and Mosquito Prevention for Large Dogs is a flea medication that works on contact. In other words, as soon as the bugs touch your pet, the effects of the flea prevention kick in, so they don’t have to bite your dog to die. This is especially important when you’re dealing with mosquitoes, which carry diseases your dog can catch if they are eaten. Plus, this also means that dogs won’t bring in flea or ticks into your home, which is a problem for medications that require a bite. Because this medicine works on a variety of insects, your canine has robust protection from whatever menace nature decides to throw at them.

From when you apply it, this flea medicine begins working within 12 hours. After that, it works for 30-days. You can purchase packages containing multiple dosages, which is often cheaper than buying each dose by itself. A dose is effortless to apply since it is a topical solution. You don’t have to worry about convincing your furry friend to take a pill. This medicine is veterinary recommended preventing fleas and diseases carried by mosquitoes.

Of course, because this is a topical medicine, there is some risk of an allergic reaction to your dog’s skin. Be sure to follow the directions on the package.

Bayer K9 Advantix II Flea, Tick, and Mosquito Prevention for Large Dogs Key Features:

  • Works on contact
  • Veterinarian recommended
  • Not as expensive as other options
  • Works for 30 days
  • Begins working in 12 hours

Best Oral Flea Medicine for Dogs: CapAction Oral Flea Treatment Small Dog

Best Oral Flea Medicine for Dogs
CapAction Oral Flea Treatment Small Dog
If your pet has a current infestation you need to fight fast, purchase this oral medication.

While we generally recommend a topical flea treatment, there are a few different reasons why an oral medication might be more suitable. In these cases, we recommend CapAction Oral Flea Treatment Small Dog. They also make medications for more substantial dogs if your canine is over 25 pounds. This medication is quite inexpensive and is made in Switzerland. It begins working only 30 minutes after your dog takes it, making it one of the fastest working medications on the market as well. A single dose should kill all the adult fleas on your canine. It is considered to be 90% effective after 6 hours. If your dog has trouble with fleas again, you can safely give another pill as often as once a day. Each pack comes with multiple pills, bringing the cost down substantially.

Of course, this medication does require a bite to be effective, though this is true of nearly all oral treatments. It is not preventative and does not work for an extended period. However, it is an excellent option for current infestations. You will likely have to treat your dog multiple times since it only works on adult fleas. However, each pack comes with six pills, which is probably far more than you need.

CapAction Oral Flea Treatment Small Dog Key Features:

  • 90% effective after 6 hours
  • Six pills per pack
  • Begins working in 25 minutes
  • For small dogs under 25 pounds

Best Budget Flea Medicine for Dogs: Hertz Topical Flea & Tick Prevention

Best Budget Flea Medicine for Dogs
Hertz Topical Flea & Tick Prevention
This medicine is much cheaper than the competition.

For a cheaper option, Hertz Topical Flea & Tick Prevention is a solid choice. It is incredibly inexpensive compared to other options, allowing you to save tons of money each year. It comes with multiple doses and needs to be used once a month. It is applied topically, which makes it one of the easier medicines to use. It can kill both fleas and ticks, including deer ticks that commonly carry disease. There are multiple weight options available – from 5 pounds to 150 pounds. You should be able to find a suitable dosage for your canine. All packages come with three month’s worth of dosages.

Of course, because this product is so cheap, it is missing some features. It is not repellant, which means fleas and ticks will still get on your dog like normal. However, when they do so, they will shortly die.

We do think it is important to point out that this product is not suitable for cats, despite the advertisements. Many of the negative customer reviews revolve specifically around the side effects this medication causes in cats. However, there were not any reports of similar side effects in dogs, which is why we decided to use it as one of the top products for this article. However, we do not recommend it for felines.

Hertz Topical Flea & Tick Prevention Key Features:

  • Very inexpensive
  • Three months of doses in each pack
  • Kills fleas and ticks
  • Topical application
  • Each dose works for a month

Best Fast-Acting Flea Medicine for Dogs: Capstar Fast-Acting Oral Flea Treatment for Large Dogs

Best Fast Acting Flea Medicine for Dogs
Capstar Fast Acting Oral Flea Treatment for Large Dogs
For protection from fleas right away, try this option.

For treating flea infestations fast, we recommend the Capstar Fast-Acting Oral Flea Treatment for Large Dogs. This medication is available for both large dogs and smaller dogs, just be sure to select the right option for your pooch. Each pack includes six treatment tablets, which start working within 30 minutes of administration. When the medication kicks in, it will begin killing all adult fleas on your canine right away. You will need to use it multiple times in all likelihood since it only targets adult fleas. The eggs on your pooch will still hatch and then need to be killed with another dosage. Luckily, you can give a dose once a day as needed. So, as soon as you notice more fleas, give another treatment.

This medication works on 90% of all adult fleas on canines within 4 hours. It takes just a little bit longer on cats, though it is still the right decision for them as well. This medicine works particularly well when you pair it with a preventative solution afterward since there are likely flea eggs and larva in your home as well. However, if your pet just got fleas, this may be the right solution by itself.

Capstar Fast-Acting Oral Flea Treatment for Large Dogs Key Features:

  • Works in 30 minutes
  • Kills 90% of adult fleas in 4 hours
  • Six doses in each package
  • Can take a dose every day as necessary

Best Long-Lasting Flea Medicine for Dogs: PetArmor Plus for Dogs

Best Long-Lasting
PetArmor Plus for Dogs
This flea medicine lasts for quite a while, making it a good choice for owners who want a long-term solution.

If you’re forgetful and can never remember when your pet’s next flea dosage is, PetArmor Plus for Dogs is a great option. Each box comes with three topical dosages, and each dose works for one to two months. That’s twice as long as most other medications on the market, making it an excellent choice for busy families. It is waterproof and protects against both fleas and ticks, including those that can cause diseases.

It begins killing fleas and ticks within 24 hours and is available for many different dog sizes. Applying the medicine is very easy since it’s topical. All you have to do is squeeze the gel onto your dog’s skin in between their shoulder blades. It kills all life stages of fleas, including eggs and larvae. This flea medication includes nearly the same ingredients as Frontline Plus, but it is much less expensive.

There were not many negative reviews, though there were a few regarding adverse side effects. However, all medications will have side effects with a small majority of dogs, so this is to be expected. Keep an eye on your pooch the first time you use this medicine, and be sure to follow the directions. If your pet has any underlying problems, it is a good idea to call your vet before using this product.

PetArmor Plus for Dogs Key Features:

  • Works for 1-2 months
  • Kills flea eggs and larvae for up to 12 weeks
  • Begins working within 24 hours
  • Prevents fleas, ticks, and chewing lice
  • Each pack includes three doses

Who Should Buy Flea Medicine for Dogs

If you own a dog, they probably need to be on some sort of preventative flea medication. Even if your dog doesn’t get fleas often, it just takes one to start a whole infestation. Plus, many flea medications also protect against other bugs, like ticks. Many of these bugs carry diseases that can be life-threatening. It just takes one unlucky bit from a tick for your dog to be infected, so they must be protected at all times.

Some medications are designed to treat outbreaks in specific. These medicines do not prevent your dog from becoming infected again, but they do kill fleas that are currently on your dog very quickly. If your dog is now infested with fleas, it might be a good idea to follow up one of these fast-acting medications with a preventative one. Even if you kill all the fleas on your dog, there are likely eggs and larvae in your carpet and furniture, which will re-infect your pet. Preventive medication will prevent this from happening.

If you’re looking for a more targeted treatment of another common problem for dogs, then you may want to check out The Best Dog Ear Cleaners.

Best Overall Flea Medicine for Dogs
Bayer K9 Advantix II Flea, Tick, and Mosquito Prevention for Large Dogs
For all-around great protection, this flea medication is suitable for most pets.

Important Features to Consider

Flea medicine for dogs should do several things well. Here’s what to consider when selecting a flea medication for your dog:

  • Long-Lasting. How long the drug lasts is one of the essential features to consider. There are two main types of flea medications: those designed for prevention, and those intended for treatment. Both of these have varying degrees of longevity, with those for prevention often lasting for months at a time. Those designed to kill fleas quickly and fight infestations usually last for only a few days, allowing your dog to be retreated often. Neither of these options is better or worse than the other. It is mostly just a matter of what you’re looking for.
  • Ease of application. Oral medications are generally harder to apply than topical applications. However, this is not the case with every dog. Your canine might eat everything but never sit still, which might make oral medications the better option. You know your dog, so choose the best option for them.
  • Effectiveness. Not all flea medications work equally, as well. Some are better than others at getting rid of fleas and preventing infestations. Sometimes, you might get a medicine that is great at preventing fleas, but quite bad at preventing ticks. To make matters even more confusing, not all medications work the same for all pets. Some pets have allergic reactions, while the ingredients just don’t work at all for others. Generally, look at the customer reviews for a general idea of how well the medication works. Still, remember that it might not necessarily work as well for your dog or area.
  • Fast Acting. Generally speaking, medications that last longer also take longer to work. Those that are designed to spot-treat infestations usually work much quicker, but don’t last as long. Like most features, it just depends on what you’re looking for. If your dog needs help with a flea infestation now, choose one that acts fast. If you’re looking for long-term prevention, you’ll probably need to settle for one that takes a little bit longer to work.

Frequently Asked Questions

What is a flea medicine for dogs, and how does it work?

Flea medicines are designed to treat flea infestations or prevent an infestation from occurring. There are two main types: those that are intended to treat a current infestation quickly and those designed for prevention. How the medication works depends on the exact ingredients. Usually, medications are either oral or topical. Most medicines require the flea to bite your dog before it begins killing them while others kill on contact.

What kills fleas on dogs instantly?

There are many oral flea medications designed to kill an infestation quickly. While they don’t work instantaneously, many do begin working within 30 minutes and kill up to 90% of fleas within 4 hours. Many of the products in our top five list do this, so head up there for some specific product suggestions.

What is the best way to get rid of fleas on my dog?

The easiest way is to invest in a flea medication designed to treat infestations. These medications work quite quickly, usually within 4 hours. After a few hours, give your dog a bath to remove dead fleas and flea eggs. Finally, invest in a preventative flea medication. These take longer to work, which is why we recommend fast-acting medicine first. However, you likely have flea eggs and larvae in your carpet and furniture, so it is essential to provide your pet with some long-term protection.

How often should I treat my dog for fleas?

If you get a preventative flea medication, stick with the direction on the package. This will keep your pet protected 24/7 and prevent infestations. If your dog currently has an outbreak, get a fast-acting medication, and then switch to a preventative one. The fast drug will quickly kill the fleas, while the preventative one will prevent them from getting them again and kill any new eggs.

Other Flea Medicines for Dogs We Reviewed

Best Overall Flea Medicine for Dogs
Bayer K9 Advantix II Flea, Tick, and Mosquito Prevention for Large Dogs
For all-around great protection, this flea medication is suitable for most pets.

We looked at 20 other flea medicines for dogs. Even though they didn’t make our five best flea medications for dogs list, they’re the best of the rest, and each is still an excellent option for your canine. The information you’ll need to compare each one is included with the listing.

Oral Flea Medicine for Dogs

Advantus Soft Chew

Advantus Soft Chew

These soft chews start killing fleas after just one hour and were designed to be tasty and convenient. Each box comes with seven chews, though there is a 30 chew box available as well.

Key Features:

  • Large and small dog options
  • Chewable
  • For dogs over ten weeks old

Cost: $26

Advantus Flea Soft Chew for Small Dogs

Advantus Flea Soft Chew for Small Dogs

These flea treats are similar to the other products made by Adventus, except they are designed for small dogs in particular. They begin killing fleas in as little as an hour.

Key Features:

  • Starts working in 1 hour
  • Flavored
  • Kills adult fleas

Cost: $55

CapAction Oral Flea Treatment

CapAction Oral Flea Treatment

These oral pills work after only 30 minutes and kill fleas on your dog whenever they are bitten. Each pack includes six tablets, allowing you to treat your pet multiple times.

Key Features:

  • Begins working in 30 minutes
  • For oral use only
  • Six tablets per pack

Cost: $19

EcoFlea by ColoradoDog

EcoFlea by ColoradoDog

These all-natural chewable keep fleas and ticks off of your dog. They’re 100% safe and made in the USA in an FDA-registered facility.

Key Features:

  • Dog-safe doses
  • No messy oils or chemicals
  • Natural ingredients

Cost: $24

PetArmor Fastcaps

PetArmor Fastcaps

These tablets start working after just 1 hour and focus on killing all the adult fleas on your pooch. You will likely have to treat multiple times as new eggs hatch, but each pack comes with six dosages.

Key Features:

  • No messy application
  • Kills adult fleas
  • Available for many different sizes

Cost: $19

Sentry CapGuard

Sentry CapGuard

These oral medications start working within 30 minutes to treat flea infestations. The tablet format makes finding the perfect dose east.

Key Features:

  • Starts working in 30 minutes
  • Veterinarian recommended
  • Kills adult fleas

Cost: $21

Fast-Acting Flea Medicine for Dogs

Advecta 3 Flea & Tick Topical Treatment

Advecta 3 Flea & Tick Topical Treatment

Since it protects from a wide range of bugs, this medication is best used in areas with lots of different types of troublesome insects. It kills all adult fleas within 12 hours of application.

Key Features:

  • Multiple size options available
  • Kills fleas and ticks
  • Waterproof

Cost: $23

Direct Protect Plus Flea & Tick Topical Treatment for Dogs

Direct Protect Plus Flea & Tick Topical Treatment for Dogs

Available for many dog sizes and breeds, this medication controls fleas, chewing lice, mosquitoes, and ticks. It protects available lime disease and is waterproof after 12 hours.

Key Features:

  • Waterproof
  • Includes a 3-month supply
  • Multiple weight ranges available

Cost: $25

Frontline Plus for Large Dogs

Frontline Plus for Large Dogs

This flea medicine for large dogs begins killing fleas instantly and keeps your dogs protected for 30 days. Each pack comes with multiple doses for long-lasting protection.

Key Features:

  • Begins working right away
  • Designed for large dogs
  • Breaks the flea’s life cycle

Cost: $75

Sentry Fiproguard for Dogs

Sentry Fiproguard for Dogs

This medicine is safe for puppies and kittens over eight weeks old and can be used on pregnant and lactating dogs. It controls a variety of different pests, including fleas and ticks.

Key Features:

  • Controls mites
  • Waterproof
  • Safe for pregnant dogs

Cost: $8

Sentry Fiproguard Plus for Dogs

Sentry Fiproguard Plus for Dogs

With the ability to control both fleas and ticks, this is a solid, fast-acting medication to choose from. Each pack includes multiple doses.

Key Features:

  • Many doses in each package
  • Tick prevention
  • Vet quality

Cost: $53

Solimo Flea and Tick Topical Treatment for Dogs

Solimo Flea and Tick Topical Treatment for Dogs

This medication protects dogs for up to 30 days after application. It is fast-acting and kills flea eggs and larvae.

Key Features:

  • Protects against fleas and ticks
  • Works for 30 days
  • Waterproof

Cost: $16

TevraPet Activate II Flea and Tick Prevention for Dogs

TevraPet Activate II Flea and Tick Prevention for Dogs

Designed for tiny dogs, the medicine protects canines down to 4-pounds in weight. It is very quality and works on a wide variety of insects.

Key Features:

  • Four-month supply
  • American made
  • Vet quality

Cost: $25

Vectra 3D Teal for Medium Dogs

Vectra 3D Teal for Medium Dogs

After eight weeks of age, medium-sized dogs can use this flea medication. It repels most troublesome insects besides mange mites, including sand flies, fleas, and ticks. It kills on contact

Key Features:

  • Monthly dose
  • Works in 5 minutes
  • Prevents and stops flea infestations

Cost: $57

Long-Lasting Flea Medicines for Dogs

Adams Plus Flea and Tick Spot On for Dogs

Adams Plus Flea and Tick Spot On for Dogs

This topical treatment lasts for a month per dose and quickly dries when applied. Each box comes with multiple doses, and it controls many different parasites.

Key Features:

  • Comes with a 3-month supply
  • Kills all stages of the flea life cycle
  • Kills ticks and tick larvae

Cost: $11

Hertz Ultra Guard Pro

Hertz Ultra Guard Pro

This very inexpensive treatment controls ticks and fleas. It can kill flea eggs as well as adult fleas, ensuring that your dog won’t get reinfested. Plus, it also repels mosquitoes.

Key Feature:

  • Many size options available
  • Kills fleas and ticks
  • Includes a 3-month treatment

Cost: $13

PetAction Plus

PetAction Plus

This formula is suitable for pets over eight weeks old and can be used on pregnant and lactating dogs. Each package includes a 6-month supply.

Key Features:

  • Kills fleas, ticks, mosquitoes, mites, and chewing lice
  • 6-month supply
  • Can be used on lactating dogs

Cost: $27

Provecta Advanced for Dogs

Provecta Advanced for Dogs

This medication repels fleas, ticks, mosquitoes, and biting flies. Each box comes with multiple doses, which last for a month each.

Key Features:

  • Once-a-month dosage
  • Long-lasting
  • Repels many parasites

Cost: $23

Vecta 3D Gold for Small Dogs

Vecta 3D Gold for Small Dogs

If you have a dog under 10 pounds, Vecta 3D Gold is a great option for them. Each pack comes with three doses that last for a month each.

Key Features:

  • Repels and kills fleas, ticks, mosquitoes, flies, lice, and mites
  • Long-lasting
  • Quick-dry solution

Cost: $30

VetGuard Plus Flea & Tick Treatment

VetGuard Plus Flea & Tick Treatment

This medicine kills 92% of all fleas within one day of application. It is waterproof and prevents both ticks and fleas. Each dose lasts about a month.

Key Features:

  • 92% effective rate in 24 hours
  • Waterproof
  • Prevents future infestations

Cost: $17

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Kristin Hitchcock