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Reasons Why Your Dog's Flea Treatment Isn't Working and What to Do

Adrienne is a certified dog trainer and former veterinarian assistant who partners with some of the best veterinarians worldwide.

Nothing is worse for you and your pup when the flea treatment isn't working.

Nothing is worse for you and your pup when the flea treatment isn't working.

Flea Treatment Doesn't Have to Be Expensive

So you purchased an expensive topical flea product and Rover is still scratching? This is sadly a common occurrence. The truth is that there is more to eradicating the flea population than applying a single product on your pet.

There are several issues you need to take into consideration before ridding your pet—and possibly your home—of fleas.

Why Are Dog Flea Treatments Not Working?

There are a variety of reasons why your flea medication may not seem to be offering any relief for your pet. The product may be a cheap over-the-counter treatment, you may be using the medication incorrectly, or you may not be keeping your pet's environment clean, which is vital to eradicating fleas. Here are some reasons why your flea treatment seems to be failing.

  • A product may cause increased scratching for a while. "I just applied a topical flea product and my dog is scratching more than ever!" I used to get these frantic phone calls when I worked for the vet's office. The answer to why this is happening is good news. The dying fleas tend to move a lot, which causes a temporary bout of intense scratching. Not to worry, this is a sign the product you are using is actually working! Indeed, according to Frontline, the fleas get hyper-excited, which draws them to the top of the coat. This makes them more visible to pet owners. Keep in mind that it takes about 12 hours for the fleas to die in most cases.
  • You're not using the right product. If you are using some cheap over-the-counter product, it may not be as effective as prescription products. Many fleas have become resistant to over-the-counter products. You certainly don't want to get cheap when it comes to pet's medication. It is worth noting that many cats and dogs have developed adverse reactions to cheap over-the-counter flea products.
  • You are using the product incorrectly. You may be underdosing your dog if you do not know their exact weight. Make sure you weigh your dog carefully before purchasing a flea product. Many vets allow you to use their scales for free. You should also avoid bathing your dog within 24 hours of applying topical flea products. If you are applying the product after a bath, make sure your dog is completely dry. Last but not least, make sure you are applying the topical product on your dog's skin and not the coat alone.
  • Fleas are still present in the dog's environment. If you are already using a prescription product and you are still seeing fleas, consider that it takes time for the fleas in the dog's environment to die. According to Frontline, several flea eggs may be present in the dog's environment, which is causing the flea population to continue growing. It takes consecutive monthly applications of topical products to completely eradicate the flea population. This is because the female flea lays up to 50 eggs per day. These eggs take about 21 days to develop into adult fleas. Once you see adult fleas, you are generally three months behind getting them under total control. The fleas you find on your dog are only a tiny percentage of the whole population.
  • You are only treating one pet. If you have multiple pets, are you only treating one? Just because one pet is not scratching as much doesn't mean they don't have fleas. If other pets are left untreated, this means there are surely flea eggs within your home. Be sure to treat all pets at the same time. Remember to use specific treatments for dogs and cats.
  • The dog is still scratching despite your doing everything right. If you have applied flea products both on your dog and in your home, why is your dog still scratching? It could be your dog is suffering from flea bite dermatitis. Just one bite from a flea may cause your dog to be miserable and the effects may be lingering for some time even after successful treatment. According to PetCoach, studies have shown that up to 40% of dogs may test positive for flea bite allergies. However, if your dog is still scratching and there are no signs of fleas, consider your dog may be suffering from some other type of allergy.

Which Products Work Best?

You may feel slightly overwhelmed by all the dog flea products on the market. The table below will help you compare one product from another so you can the best deal for your money.

  • Frontline Plus contains fipronil, which kills adult fleas within 12 hours. It also contains the insect growth regulator methroprene, which kills fleas before they hatch out of the eggs.
  • Advantage II is a topical product that kills adult fleas It stops them from biting within five minutes and kills them within 12 hours. The insect growth regulator pyriproxyfen prevents fleas from developing into the next stage.
  • K9 Advantix is a topical product that kills fleas, ticks, lice, and flies. The imidacloprid and permethrin in the product paralyzes and kills adult fleas while the pyriproxyfen prevents the flea from developing to the next stage.
  • Comfortis is one of the most effective products on the market for killing fleas. It's an oral pill that not only kills fleas but also prevents fleas from developing into adults. It's given to dogs just once a month. Here's some more information.
  • Program is an oral pill that stops the flea reproduction cycle. It inhibits the development of flea eggs. It must be used with a flea adulticide if adult fleas need to be killed.
  • Capstar is an oral pill that has a 90% effectiveness against adult fleas on dogs, which were killed within four hours. However, it does not have an effect on fleas in the dog's environment.
  • Vectra 3D is a topical product that kills adult fleas and other pesky parasites. It has pyriproxyfen, which prevents fleas from developing into the next stage.

Comparison of Flea Treatment Products

ProductActive IngredientMethod of AdministrationHow It WorksDosage

Frontline Plus

Firponil and Methoprene


Kills adult fleas as well as larvae. It's also effective on ticks. Treatment is effective for 30 days.

Once per month

Advantage II

Imidacloprid and Pyriproxyfen


Kills fleas at multiple life stages, thus preventing their proliferation. This treatment also works on lice. Kills fleas within 12 hours and is effective for 30 days.

Once per month.

K9 Advantix

Imidacloprid, Permethrin, and Pyriproxyfen


Kill adults fleas, larvae, and eggs. Also kills ticks and mosquitos as well. It begins working within 20 minutes and takes 24 hours to go into full effect.

For just fleas, apply once every month. If flea infestation is heavy, you should apply treatment once every week.



Oral Pill

Fleas are exposed to lufenuron, which inhibits the development of eggs. This effectively kills the flea lifecycle. This is a long-term treatment and does not kill adult fleas.

Once every month.



Oral Pill

This is a quick and short-term treatment that can begin killing adult fleas within 30 minutes. It can kill most fleas within four hours. The chemical interferes with neurotransmission of the flea, killing them quickly. This treatment does not prevent new fleas from getting on your dog.

You can give this pill as often as once a day.

Vectra 3D

Dinotefuran, Permethrin, Pyriproxyfen


Treatment works by killing adult fleas and repelling new pests. It is also effective on ticks, mosquitos, and lice. Can kill pests within six hours.

Once every month.



Oral Pill

This treatment attacks the nervous system of fleas and kills them within 30 minutes. It repels other adult fleas, but it does nothing to eggs that may represent on your dog.

Once every month.

Vacuuming your carpet and furniture is a great way to combat a flea infestation in your home.

Vacuuming your carpet and furniture is a great way to combat a flea infestation in your home.

How to Get Rid of Fleas in Your Home

Flea treatment goes beyond simply getting rid of the specimens on your dog. If a treatment only shows temporary relief, it is possible that fleas are living somewhere in your home and are getting on your pet after treatment. If you find that there are fleas in your home, here is what you can do.

  • Vacuum your house. Using a vacuum can get rid of fleas as well as their eggs. Be sure to focus on areas where your dog frequently hangs out. You should especially target carpets, furniture, and cracks in wood flooring. These are good hiding spots for fleas. If the infestation is severe, you should vacuum daily.
  • Steam clean the carpets. If there is a major flea problem in your home, you may have to steam clean your carpets. This will kill adult fleas, but it may not remove all the eggs. Multiple cleaning may be necessary.
  • Use hot and soapy water to clean the dog bed. If your dog sleeps indoors, you should use hot, soapy water to wash their bedding. This will kill the fleas. If your dog frequently lays in other beds, you should give that bedding the same treatment.
  • Use an insecticide. You can potentially use a spray for indoor flea treatment. You should do this when no one is inside and should make sure there is no contact to the sprayed areas until it is dry. Use a spray that contains permethrin, which kills adult fleas, as well as methoprene, which kills eggs, larvae, and pupae.
Flooding your yard is a great way to get rid of fleas as well as flea dirt.

Flooding your yard is a great way to get rid of fleas as well as flea dirt.

How to Get Rid of Fleas in Your Yard

If your dog spend a lot of time outside, they may be susceptible to fleas that are present outdoors. Any treatment you give them will be in vain if any infestation in the yard is not dealt with. Here is how you can eliminate fleas from your yard.

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  • Flood your yard. Flooding your lawn will kill any fleas living there. It will also wash away their feces, which flea larvae eat. Be sure to flood areas around any trees, fences, and where your doghouse is.
  • Spray an insecticide. Be sure to use an environmentally-friendly spray and to avoid spraying anything your dog or any children can come into contact with. Spray the area your dog usually hangs out in as well as under any decks, patios, or around shrubs. A good insecticide to use is diatomaceous earth. This chemical works by absorbing all the moisture from the exoskeleton of the fleas and dehydrates them.
  • Place nematodes in your yard. Nematodes are worms that feed on flea larvae, as well as other pests like termites. You can purchase them and spread them around your yard. Put them in shady areas where the fleas are located.
  • Spread cedar chips in your yard. Fleas hate the smell of cedar. You can spread some chips where you have located fleas. This is a great method to prevent new fleas from coming into your yard.

How to Test for Flea Dirt

How can you tell if those black specks on your dog's coat are just debris or actual flea droppings? There is an easy way to find out. Collect the dirt and place it on a wet paper towel. If the dirt "bleeds" out and becomes red when rubbed, then you are looking at flea droppings, which are made of digested blood. If the color remains the same, then you are very likely dealing with actual dirt or debris.

Another good way to catch fleas and flea dirt if your dog has long hair is to brush your dog with a flea comb and look at what you collect. You may find actual live fleas or some traces of flea dirt. In this case, drown the live fleas in a bucket of water.

Are Fleas a Serious Threat?

Fleas are a lot more than an annoying pest. They can actually cause some health issues for your pets. They can potentially be a problem for humans as well—these are the same little pests that were responsible for spreading the bubonic plague. Here are some of the major problems fleas can cause.

  • Flea allergy dermatitis: This is the most common issue where your dog is allergic to the saliva of fleas. This causes constant scratching and biting, which further leads to bald spots, hot spots, and potential infections developing.
  • Tapeworms: If your dogs swallows a flea, they may get tapeworms. This parasite will live in their intestinal tract and take away vital nutrients from your dog.
  • Anemia: In extreme cases of a flea infestation, your dog can become anemic if left untreated. This is caused by the massive loss of red blood cells.
  • Bites to humans: Fleas can enjoy a bite from humans as well. While they can't live on us like they do on pets, they can potentially spread diseases. The most common is cat-scratch disease, which is caused by the bartonella bacteria they can spread.

This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.

Questions & Answers

Question: My dog ate a Bravecto pill, why is he still scratching?

Answer: It is possible to get flea bites while a dog is on a preventative as Bravecto if he frequents outdoor areas where fleas will inhabit such as under trees, brush, at dog parks, etc etc. Also, Bravecto is a flea prevention that works by stopping fleas from reproducing and continuing their life cycle. It works by killing a flea when it does bite. So your dog may be scratching because he may feel the flea biting.

Question: My cat is too wild to apply a topical product for flees. Is there a pill for cats?

Answer: I hear you. Have seen cats literally startle and jump in the air when a topical flea product is applied. There are nowadays several flea treatments for cats in pill form. One of them is Capstar flea tablets for cats. However, I just read some scary reports of cats having serious side effects, with some even dying from it. Perhaps, you can wrap your kitty Burrito style in a blanket when your cat is calm and relaxed and then uncover just slightly the area to apply? I have seen vets in our office immobilize cats by wrapping them in a towel or blanket this way when they needed shots or other procedure done. Please be careful, though. The best and safest option would be to bring your cat to the vet. They may charge you a little fee, but they are experts in restraining cats professionally.


Tabatha Simmons on June 23, 2020:

Is seresto flea collats a good way to go

Selene on May 04, 2019:

My 6 month old maltease had a tick I applied the frontline for 5 to 22 lb but she’s still scratching not all the time but sometimes.i don’t see no more ticks or fleas on her so I’m a little confused as of if the product work or not.

JONNA on January 29, 2019:

Anthony, Im a retired pet groomer and I use to use the Zodiac dip on many dogs and it was the best back then before frontline and advantage came out.

Adrienne Farricelli (author) on August 23, 2018:

Steve, you may need to use products to kill the flea eggs hiding in areas around the home.

Steve on August 17, 2018:

My 2 dogs still have fleas after I gave them frontline plus almost 3 weeks ago

Anthony on September 04, 2017:

What about the Zodiac brand? It is sold my central Garden & pet company

Adrienne Farricelli (author) on January 22, 2013:

We used to sell program and it sold pretty well, not too sure why it's not as popular as before. I will have to stop by and look at your hub, thanks for stopping by.

SmartAndFun from Texas on January 22, 2013:

I have used Program on my dogs for probably about 20 years. It works wonderfully, and there's no poisonous insecticide to worry about. We have zero fleas! I like it so much I wrote a HubPages article recommending it. Several years ago doctors figured out it helps protect against ringworm and yeast, also. I think it's a shame vets don't recommend it much anymore. It seems like hardly anyone has heard of it, even though it works great and is very safe.

Peter Geekie from Sittingbourne on November 09, 2012:

I'm sorry but please do not use tea tree oil or any essential oil on cats or dogs. It is extremely toxic and will cause irreversible damage to the animals kidneys and liver. You will not see an immediate reaction but the organs will be damaged and in the case of an older animal with impaired liver and kidney function could cause complete failure and death.

If you need further info please look on my hub pages.

kind regards Peter

Lindsay on October 03, 2012:

Oral flea preventatives tend to be more effective. Frontline was once a great product, however, we are starting to see some resistance because it's been out for several years. Products such as Trifexis and Comfortis are the most effective and it's much easier than the topical options. Don't waste your money on the stuff at Walmart and Petsmart. There's a reason those products are sold there and not at a lot of vet clinics. Shampoos are great for getting rid of live fleas, but don't act as a preventive agent. Most importantly, have your dogs on heartworm prevention! Heartgard is a great product, and Trifexis, which I mentioned earlier, is actually a combination flea and heartworm prevention.

Carla Kohlhase from Corpus Christi, Texas on September 22, 2012:

Tea tree oil is another great alternative to assist in ridding flea infestations. It's also soothing to the animals skin. The chemical based treatments can be harsh on a dogs skin. I usually try to find a shampoo that is natural, as well as soothing to the irritations afterward. An anti-itch, or oatmeal shampoo works great when tea tree oil can't be used.

Adrienne Farricelli (author) on March 24, 2012:

Be careful with the garlic though as long term it can cause heinz anemia. Read here:

JubePlaysGames from Canada on March 24, 2012:

I used to use Advantage, and while it is effective, it's also poison and can cause some really bad side effects.

Now I feed my dogs garlic and they haven't had a single flee or tick in 2 years. For my 35 pound guy I give a 1/2 small clove every second day, and my 85 pound guy gets a full decent sized clove every second day.

As for heartworm... I have them tested every year and give them Black Walnut during the spring and summer months to prevent heartworm.

Adrienne Farricelli (author) on March 23, 2012:

It does sound like she has flea bite dermatitis which causes those crusty wounds you are most likely seeing. Treating the yard is very important, especially under decks where the fleas thrive. Make sure you use an insect growth regulator . If there are fleas in the yard, it just takes one flea to get on her and bite her before dying and she is off scratching and biting. Sure sounds like a challenge!

beadreamer247 from Zephyrhills, FL on March 22, 2012:

Alexadry, first of all thanks for responding to my question in regards to my dog's problem (and mine)! I've read all this before on the internet - all this is familiar to me and I never had any issues with previous dogs. Now I have 3 dogs, but with just one of them I have the severe problem that absolutely nothing is effective. All the medication you mentioned I have tried and others (except for the last one in your chart - must be newer). Also tried the ones over the counter, shampoo, have treated the home again and again etc.....After treatments always the same result....latest within a week of treatment I have fleas on her and I do see them. I had times when I actually "overdosed" her, because I had no other choice and the situation was so bad.

Because she tries to rub off any topical treatment because of the smell (even when my other dogs got treatment she roams around trying to get rid of the odor)I thought for a while that was the reason and switched to oral treatment, which was praised so highly by so many who I spoke with....Revolution. The result - fleas after a week again. But as usual only her but not my other dogs, they were fine! In addition she reacts strongly to fleas and bites herself bloody - she never really looks nice and healthy.....always full of wounds.

The only think we have never done is treating the yard - that's what we will try as the last bring some relief.

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