Superb Dog
what kills fleas on dogs instantly

What Kills Fleas on Dogs Instantly? Prescription, OTC, and Home Remedies

Fleas can infest your dog quickly and ruthlessly. We look at what kills fleas on dogs instantly as well as many options for controlling this persistent parasite.

With about 2,000 species of fleas, there’s no shortage of these pests that are a leading cause of itching and scratching in dogs. They carry potentially dangerous bacteria that, when passed to dogs, may cause severe allergies and illnesses.

Any dog owner knows how irritating fleas can be and how quickly a flea problem can get out of control. Fleas need to be eliminated fast or they reproduce and can cause serious problems and infestations. 

When you’re asking, “What kills fleas on dogs instantly?” understand that many effective treatments take a little time to work. Some treatments and medicines kill fleas instantly. But if you want to learn how to get rid of fleas on dogs naturally, there are many options for that, too.

Read on to learn more about prescription, over-the-counter, and home remedies that can answer the question, “What kills fleas on dogs?”

Prescription Flea Treatment for Dogs

Prescription medications require a trip to your local vet. Typically, prescription flea treatment for dogs can include injection, tablets, topical treatment, powder, injections, and other forms of medication regulated by the Food and Drug Administration (FDA).

Since prescription medication involves keen oversight and regulations, you can rest assured the flea treatment your dog gets will have been tested thoroughly and considered safe.

Afoxolaner (NexGard)

NexGard is a chewable tablet (beef flavored) that begins working within four hours of ingestion and protects your pet for 30 days ‒ given orally once per month. Afoxolaner is often considered the best prescription medicine to kill and prevent fleas.

This treatment is recommended for dogs over 4 pounds and puppies of 8 weeks or older. It is also easy to administer. 

It works by attacking the central nervous system of invertebrates (like fleas) rather than the nervous system of mammals (like your dog). Unlike many topical flea medications, which work their way through the tissue underneath a dog’s skin, NexGard directly enters the bloodstream before ending up in these fatty tissues where it affects the fleas when they bite.

NexGard basically creates such an intense hyper-excitation of the flea’s nervous system that the uncontrollable activity overwhelms the flea and kills it.

A rare but significant side effect of NexGard is seizures.

Bravecto Chews

Bravecto is a prescription-only treatment for fleas and ticks that is chewable. The medicine begins working in 2 hours and can kill any fleas on your dog within 8 hours. A single administration protects your dog against fleas and ticks for up to 3 months.

However, before administering the medicine, you should ensure the dosage corresponds with each type of weight. This is because it is suitable for dogs weighing about 4 -124 pounds.

Similar to NexGard, Bravecto works by saturating the fatty tissue under your dog’s skin. Fleas that bite the skin die.

Like NexGard, a rare but significant side effect of Bravecto is seizures.

Spinosad (Comfortis)

Comfortis is a beef-flavored chewable tablet that kills both fleas on dogs and cats. It kills fleas the fastest of any of the prescription medications — after 30 minutes. 

The medicine is for dogs that weigh at least 5 pounds and are at least 14 weeks of age. It provides complete flea protection for your pet for one month.

It is considered to be in the same class as NexGard and Bravecto (isoxazolines), and kills the fleas through the same basic process.

Comfortis has yet to be tested for use in breeding, pregnant, or lactating dogs.

what kills fleas on dogs instantly

Over-the-Counter Flea Treatments for Dogs

Also known as off-exchange trading, over-the-counter treatment involves drugs you can buy from a pet store or a supermarket without a prescription. These flea treatments without prescriptions are readily available because your dog’s body does not absorb them. 

Such treatments may include topicals, shampoos, dips, flea and tick spray, or even collars. Examples of commonly used over the counter flea treatment include: 

K9 Advantix II

Whether you have a small dog or a large dog, you can always go for k9 Advantix II. This treatment is a solution for not just fleas and ticks, but lice, and mosquitoes as well.

The medicine is easy to administer and should be applied once a month as it can last up to 30 days. Additionally, the medication becomes waterproof after 24 hours, allowing you to bathe your pet without diminished effectiveness.

In recent years there have been a number of reports that popular topicals like K9 Advantix II and Frontline Plus (see below) have been losing their effectiveness as fleas as fleas are now much more resistant to them. If these products don’t work for you, you may want to try an alternate product such as one from the isoxazoline class described above.

Frontline Plus for Dogs

Frontline Plus is an effective treatment that kills and prevents fleas, lice, and ticks. The medicine should be used once per month as its effects last up to 30 days.

Usually, this treatment is available for all dog sizes, and its application is easy. However, if you own a cat, do not use the treatment around it as it can be harmful.

Nitenpyram (Capstar)

Capstar is a fast-acting flea pill that ends infestation within a short time. After taking the medication, it takes about half an hour to start killing the fleas effectively. It leaves the dog’s system within 72 hours.

Capstar is an oral tablet widely used by dog owners as it is safe for kittens and puppies two months and older. Technically, it can be used frequently as needed.

However, it is important to note that Capstar is not an alternative for any ongoing preventive medication for your dog. Unlike NexGard and other medications in that class, Capstar only kills adult fleas on the dog; it does not kill flea eggs or larvae.

fleas on dog

Flea Collar

You may also want to try a flea collar to protect your dog against fleas. Flea collars work by releasing sustained but low-dose ingredients that eliminate pests, such as fleas and ticks.

The Seresto flea and tick collar is one of the most affordable flea treatments. But, its affordability does not make it necessarily less effective. In essence, the collar provides eight months of flea and tick protection to your dog.

Moreover, Seresto flea and tick collars are non-greasy, odorless collars and kill fleas in 24 hours. 

How to Get Rid of Fleas on Dogs Naturally

Luckily there are several home remedies to help you try to get rid of fleas on dogs without having to spend a lot of money or consulting a vet. 

In all honesty, natural flea treatments are generally less effective than medications. Of course, there is the tradeoff of introducing the risk of chemical and medicinal ingredients vs. less effectiveness, so it’s up to you to determine what works best and feels the safest for your dog.

Here are several home remedy flea treatments that work to some degree.


What kills fleas on dogs that’s natural and non-toxic? Lemon. 

You can make a citrus spray by slicing lemon, adding a little water, and bringing it to a boil. Pour the solution into a spray bottle and leave it to sit overnight, then use the spray on the infected areas in your home.

Use lemon juice to clean your dog by dipping the dog’s comb in the solution and make multiple passes through the fur. If your dog has a short coat, use a cloth dipped in lemon juice to wipe it. Also, you can dilute lemon juice and add a splash of pet shampoo.

Coconut Oil

Coconut oil has long been used as a flea treatment for dos. Read more about coconut oil for fleas on dogs and how it can soothe the effects of flea bite dermatitis.

Essential Oils 

Peppermint, rosemary, and lavender oils are sometimes suggested as flea remedies because they do not smell good to fleas. Their effectiveness and safety is not certain. If you do choose to use essential oils, you should always dilute them before spraying or applying them to your dog’s coat.

Keeping essential oils in your living space can also make your space smell nice. However, you should be cautious with essential oils, as some might be harmful to your dog. Again, consult with your vet for advice on the safety of their use.


Salt may seem like a simple method, but it can be an effective at-home remedy for fleas. Salt, as a dehydrating agent, sucks moisture from the fleas ‒ which dries and kills them.

Usually, fleas lay eggs in warm and dark places, like carpets or on the cushions. To treat fleas with salt, sprinkle it in those areas, let it rest for 1-2 days, and then thoroughly clean your home.

Flea Comb

If you’re looking for options that answer the question, “What kills fleas on dogs instantly?” a flea comb might not be the kind of solution you’re looking for. However, a flea comb is a natural way to kill fleas. Usually, flea combs come in different sizes with closely spaced teeth, removing fleas, eggs, and feces.

When using this method to get rid of fleas, focus on the most frequented areas for fleas like your dog’s neck and tail/base. Make sure you kill any fleas the comb picks up by submerging it in hot or soapy water.

While combing out fleas from your dog’s coat and then killing them will certainly result in dead fleas instantly, it usually won’t solve the greater problem of a flea infestation as others are living in the dog’s environment and will likely soon replace the dead ones on their host.

Apple Cider Vinegar (ACV)

Another way to attempt to naturally eliminate fleas is to mix apple cider vinegar with water. The acid in apple cider vinegar creates an unconducive environment for fleas.

To do this, add a tablespoon of vinegar to your dog’s water and spray it on your dog’s coat and underbelly. This will give your dog’s skin an acidy taste, hopefully making fleas stay away.

dog scratching fleas on its body

Diatomaceous Earth

Diatomaceous earth (FleaBusters) is one of the most effective non-toxic treatments for fleas. It is a fine powder made of microscopic remains of fossilized silica, diatoms, and other natural minerals. The powders work to kill the fleas by drying them out, as it is a dehydrating agent.

Let the diatomaceous earth work miracles in your home by sprinkling it over areas you suspect have high flea activity. Wait for a few hours, then do a thorough cleaning.

Be aware that some have reported asthma and other respiratory problems from using diatomaceous earth.

Flea Repelling Plants

Some plants contain chemicals, oils, and compounds that smell unpleasant to fleas. You can plant these flowers in your flower beds or pots and place them near your windows and doors to rid of the fleas.

Some of the plants you can try to help you get rid of fleas on dogs naturally include:

  • pennyroyal
  • lavender
  • clove
  • spearmint
  • thyme
  • chrysanthemums

Dish Soap

Water mixed with dish soap solution acts as glue and taps fleas due to its high viscosity. You will need to fill a bowl with warm soapy water and place it in the flea-infested room.

Since fleas are likely to be active at night, it is advisable to use this remedy late in the evening or at night. For this remedy to work effectively, repeat the process with a fresh batch daily.

Also, Dawn dish soap has developed an almost mythical reputation as a flea shampoo for dogs. Read more about whether Dawn dawn dish soap kills fleas on dogs.

Herbal Flea Spray

You can make herbal flea spray with non-toxic products around your home. All you’ll need is to mix about 4 L of vinegar, 500 ml of lemon juice, 2 L of water, and 250 ml of witch hazel in a large spray container.

The next step is to ensure that every corner of your home is clean. Then spray your natural flea remedy on furniture, around ped beddings, window sills, and your carpet.

Light Trap

One observable behavior of fleas is that they are attracted to light, and you can use this to your advantage. Put a yellow light bulb dangling above a sticky mat or use glue strips to trap the fleas.

However, this trap is only effective in dispatching fleas that can see the light but will not help you rid of fleas on your pet.

Get Rid of Fleas, Quickly!

You might still wonder, what kills fleas on dogs instantly? While over-the-counter and home remedies can sometimes effectively kill fleas on dogs, prescription medication is usually the best option for fast relief.

For longterm prevention and control of flea infestations, the best protocol is regular medication combined with diligent vacuuming of carpets and regular cleaning of your dog’s bedding and other household living areas.

Your veterinarian should be your ideal information source because their recommendations rely on products with high levels of efficacy and safety.

Superb Dog Editor

Superb Dog Editor