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How Soon Can I Give My Dog Another Flea Treatment?

Flea treatment is usually applied as often as specified on the label. Flea products can be administered more often than specified in some cases, but only if recommended by your veterinarian. Never do so on your own, as you may poison your dog.

Fleas and ticks are the number one enemy of dogs and their owners. 

Massive flea infestations in puppies can often be fatal if not treated in time. Such a small body has a reduced amount of blood compared to an adult dog. Fleas decrease blood volume through feeding until the puppy reaches severe anemia, which can lead to death.

Fleas have a complex, four-stage life cycle. If you want to get rid of fleas and prevent them from reinfesting your dog or home, you need to consider their life stages. 

Spraying an insecticide once on your dog or in your home is not enough.

In this article, you will find out what to do if your dog has fleas, how often you should give it a flea treatment, what happens if you put flea medicine on your dog too soon, and more.

What to Do if My Dog Has Fleas?

If your dog has fleas, the best way to get rid of them and prevent future infestation is to use flea medicine on your dog and in your home. You have many options to choose from: antiparasitic shampoos, spot-on pipettes, flea collars, or chewable tablets. 

Massive flea infestations are the easiest to notice – your dog scratches continuously until it self-mutilates, its coat looks dirty, and the fleas can be seen roaming back and forth through your pet’s fur. 

Whether your dog has a few fleas or hundreds, it has to be treated with flea products.

Always follow the instructions on the label and use only products designed for your dog’s weight and age. Do not use more than one product at a time without consulting your veterinarian.

Some dogs may be more sensitive to the active substances in these products and develop mild to severe allergic reactions. Even if you strictly follow the instructions on the label.

Contact your veterinarian to find out if the chosen product is right for your dog, and call them immediately if you notice your pet is behaving strangely after applying for flea medicine.

Don’t overdo flea control. Too many toxic products on and around your dog can be harmful or even deadly.

What Does a Flea Bite on a Dog Look Like
Image Source

How Often Can I Give Flea Treatment to My Dog?

The duration of flea medication depends on the product you want to use. Pipettes are applied once every four weeks and collars every 4-8 months. Shampoos and powders are not as effective, but they can be used in pregnant females and puppies, unlike other products.

Products applied to your dog, such as spot-on pipettes, collars, or powders, work by storing the active ingredients in the sebaceous glands[1]

When a flea climbs on a dog, the substance acts on the flea’s nervous system, making it unable to feed. This is different from tablets.

The active substances in chewable tablets get into your dog’s bloodstream. When a flea comes to feed, it ingests the pesticides.

How often you need to administer these products to your dog depends on the product you want to use. Each product has the duration of action written on the packaging. If you feel the product you have used has had little to no effect on your dog, contact your veterinarian for guidance.

The general applications intervals for flea medication are as follows:

ProductApplication interval
Spot-on pipettes4 weeks
Collars4-8 months*
PowdersOnce/twice per week or twice per month*
Sprays4 weeks
ShampoosEvery one or two weeks*
Chewable tablets4-5 weeks*

*the application interval depends on the product

Related: How Often Can I Give My Dog Flea and Tick Treatment?

Spot-on Pipettes

Spot-on pipettes are the easiest to apply. You have to open the product and empty its content on your dog’s skin on the top and back of the head.[2]

The effects of these products usually last up to four weeks. If the product is not effective, your veterinarian can recommend you to use the same or another product within two weeks of the first application. 

This method is also used in cases of massive infestations.

Always talk to your veterinarian before making a decision. Otherwise, you risk intoxicating your pet.

Related: How to Apply Flea Treatment to Dogs

Spot-on Pipettes

Flea Collars

The preventive efficacy of antiparasitic collars has been demonstrated through studies[3]. Although these products are safe and well-tolerated by most pets, some can leave chemical residues on the dog’s fur and lead to intoxication.[4]

In massive infestations, the collar’s potential can be amplified by applying a spot-on pipette every four weeks. But this is something you should do only if your veterinarian recommends it.

Make sure you don’t touch the area where the collar is. If you do, wash your hands thoroughly.

Flea Collar Poisoning in Dogs

Chewable Tablets

Chewable tablets are preferred by many dog owners because they are easy to administer, leave no residue on the dog’s fur, and the risk of an allergic reaction is very low.

These products are also more suitable for families with small children because they have a lower risk of intoxication among family members. Young children and other family members can put their hands in their mouths after touching the area with flea medication and have a higher risk of intoxication.


Flea sprays should be specially designed for pets. Do not confuse sprays with pesticides for home and garden with those for pets and vice versa. You risk intoxicating your dog or having no effect.

Although most spray products are very effective in killing fleas, some brands also ensure flea prevention for four weeks.

Sprays flea treatment for dogs


Antiparasitic shampoos are suitable for pregnant and lactating females or puppies because the harsh active ingredients are washed out when rinsing.

Antiparasitic shampoo for pets

Using Pesticides in Your Home

In addition to applying flea medication, it is also important to make your home flea-free. Flea eggs can often be found where your dogs sit around the most. These eggs hatch in a few days, and the torment recommences.

Wash your pet’s bedding in hot water and spray with insecticide on the surfaces and places that have come in contact with your dog. Once you remove the fleas from your dog and its surroundings, you can rest easy.

Should I Give My Dog Flea Treatment in the Colder Months?

Dogs should be treated for fleas all year round, regardless of the season. Even if the number of fleas decreases during the cold months, they can still climb on your dog.

The myth that fleas disappear in the winter is false. They can survive temperatures as low as 33°F (0.5°C) for approximately five days. 

Fleas need a host to pass by, jump on it, and get in the house where it is warm so they can grow and multiply.[5]

What Happens if You Put Flea Medicine on Too Soon?

If you put flea medicine on your pet too soon, you risk intoxicating it. At best, nothing will happen.

It is normal to find fleas on your dog for a few days after applying for the flea medicine. You may feel the urge to reapply the product again, but keep in mind that flea medicine starts working within 48 hours after application. 

You may also see your dog scratching more than usual during this time.

Never apply another antiparasitic product earlier than two weeks from the first application. The concentration of active ingredients will be too high for your dog, and you risk intoxicating it.

Early reapplication of antiparasitic products should be done only on the recommendation of your veterinarian.

veterinary checking on dog

Symptoms of Antiparasitic Poisoning

Pesticide intoxication can occur in dogs if:

  • You haven’t used the recommended concentration for your dog’s weight and age
  • You have used several products at the same time
  • You reapplied the product too early

Symptoms of flea poisoning in dogs may differ from case to case and include:

  • Weakness
  • Lethargy
  • Hypersalivation
  • Incoordination
  • Dilated pupils
  • Gastrointestinal upset
  • Seizures
  • Itchiness and redness
  • Loss of appetite
  • Death in some cases


Always respect the reapplication interval mentioned on the package. Each product has a certain period in which it takes effect. Never apply antiparasitic products earlier than two weeks, as you risk intoxicating your pet.

If your dog still has fleas after applying the product, talk to your veterinarian to find the best remedy for your pet.


Should I Give My Dog Flea Treatment Even if I Can’t See Any Fleas on Them?

Flea medication should be applied even if you do not see fleas on your dog, all year round. Besides the fact that these products kill fleas, they also help prevent future infestations.

About Iulia Mihai (DVM)

Dr. Iulia is a certified veterinarian with more than 10 years of experience in the field. With extensive knowledge of diet, care, and medication, she helps Misfit Animals provide readers with accurate knowledge on technical topics.

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