How do flea collars work?

Flea collars work by sending a continuous slow release of medicine into the animal’s dermis (coat and skin) that kills fleas and ticks on contact and repels them. It spreads over the whole dermis and continues working for a specified number of weeks or months.

Are flea collars safe?

While they are safe for the most part, flea collars are not suitable for all dogs. They’re typically only recommended for puppies 12 weeks and older, and they shouldn’t be used on senior, pregnant, or nursing dogs, either. Further, some insecticides can interact with other medications your dog may be taking, so you’ll want to consult with your dog’s veterinarian before using a new flea collar on them.

Do dog flea collars work on cats?

According to Riley-Wheeler, some flea collars can be used on cats, but you have to make sure they are specifically labeled for cats. She says, “Some of the IGR's (insect growth regulators) in the dog collars can cause neurological side effects in cats.“

How long do flea collars last?

Most brands last from three to eight months, so be sure to check packaging before purchasing. You should always change your dog’s flea collar after the time period recommended by the manufacturer. You may also want to put a new collar on your dog if you notice its effectiveness is decreasing.

Do flea collars kill fleas?

Yes, but it can take some time. Flea collars typically begin releasing chemicals as soon as they’re placed on your dog, and, in general, adult fleas should be killed within a few days. (This can vary depending on the product, so read the product packaging for more precise timelines.) However, it can take up to 30 days for a flea infestation to be eradicated, as flea eggs and larvae may still be lingering on your pet or in your home.

The 5 Best Flea Collars for Dogs in 2023

Fleas can lay between 20-40 eggs a day, which makes the blood-consuming parasites tricky to eliminate. While oral treatments and topical applications are some of the most effective methods for ridding your puppy or adult dog of fleas, preventative measures like flea collars can provide additional preventative protection over time.

Flea collars are convenient to use because they release medication slowly, over several months, and are less messy than topical treatments. However, they're best considered supplemental options. We consulted with Kristen Riley-Wheeler, a vet tech at Abbot Road Animal Clinic in East Lansing, Michigan, and other veterinary sources for this article, and have concluded that oral or topical solutions should be preferred by most pet owners.

As with any medical treatment, it's best to consult with your veterinarian before using a flea collar, especially since they contain insecticides that are potentially risky for other pets in your house. Also, because flea collars use a variety of different insecticide chemicals, it's important to closely monitor your dog for skin reactions during initial use.

Our top pick, the Seresto Flea and Tick Collar for Dogs, features a controlled release of imidacloprid and flumethrin, which provide effective coverage across your dog's body. It also comes in three sizes, works for up to eight months, and targets all life stages of the parasites. We also have several other recommendations that may work even better for you and your dog's needs.

Our Top Picks

Best Overall:

Seresto Flea & Tick Collar for Dogs at Amazon

Jump to Review

Best Budget:

Hartz UltraGuard Pro Flea & Tick Collar at Amazon

Jump to Review

Best for Small Dogs:

Zodiac Flea and Tick Collar for Small Dogs at Amazon

Jump to Review

Best for Large Dogs:

Adams Flea and Tick Collar For Dogs at Amazon

Jump to Review

Best Environmentally Friendly:

Vet’s Best Flea and Tick Repellent Dog Collar at Amazon

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In This Article

Our Picks
What to Look for
FAQ
Why Trust The Spruce Pets?

4.8

Amazon

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What We Like

Suitable for most adult dogs and even cats
Water-resistant

What We Don't Like

Bathing or swimming can limit the collar's effectiveness

Our top pick for a flea collar for dogs is the Seresto Flea and Tick Collar. Using a unique combination of ingredients, it slowly releases chemicals that kill and repel parasites before they get a chance to bite into your dog and start feeding. Delivered in low doses, the chemicals spread over the animal’s body to provide effective head-to-tail flea and tick control.

Easy to use and odor-free, this collar prevents fleas and ticks for up to eight months, killing parasites on contact. Once placed on your pet, it begins killing and repelling fleas within 24 hours. Proven to be effective against fleas, ticks, and lice, the wide-ranging utility of the Seresto Flea and Tick Collar means you don't have to worry about multiple treatments for multiple environmental pests.

It is also water resistant, which means you can still bathe your dog or let them go swimming. However, Seresto recommends limiting baths to once a month to maintain the collar's effectiveness. The flea collar will also have a shorter useful duration if your dog swims often, so Seresto recommends replacing the collar every five months if you have a frequent doggy paddler in the water.

Seresto flea collars are available in Large Dog and Small Dog formulations, so all you need to know in advance is whether your dog is more or less than 18 pounds. It also is easy to fit, with a ratchet adjustment and a thin, unobtrusive strap that's unlikely to annoy your pet.

Price at time of publish: $55

^{Sizes: Small, large︱Active Ingredients: Flumethrin, imidacloprid︱Effective Against: Fleas, ticks, larvae, chewing lice, sarcoptic mange︱Duration: Lasts up to 8 months}

4.7

Hartz UltraGuard Pro Flea & Tick Collar for Dogs and Puppies

Amazon

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What We Like

Adjustable
Water resistant
A fraction of the price of our favorite flea collar

What We Don't Like

Takes several days to become effective against ticks

The Hartz UltraGuard Pro provides full-body protection against both fleas and ticks. It uses a combination of tetrachlorvinphos and methoprene to kill and repel fleas in all life stages, including adults, larvae, and eggs, preventing flea eggs from hatching. It also protects against ticks, making it a good summertime defense against lyme disease.

Each Hartz UltraGuard Pro collar provides full-body protection for up to seven months and it can be used on dogs as young as 12 weeks. The collar fits dogs with necks up to 26 inches, so it can be used on both large and small breeds, and it even has a reflective strip for increased visibility and safety at night. The UltraGuard Pro is water-resistant, so you don’t have to worry about your dog getting wet. The collar’s affordable price point is an added bonus to an all-around solid flea-prevention product.

While the Hartz UltraGuard will begin killing fleas immediately, it takes a few days for full protection to kick in.

Price at time of publish: $7

^{Sizes: One size, up to 26-inch neck︱Active Ingredients: Methoprene, tetrachlorvinphos︱Effective Against: Fleas, ticks, flea eggs, flea larvae︱Duration: Lasts up to 7 months}

Zodiac Flea and Tick Collar for Small Dogs

Amazon

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What We Like

Kills adult fleas and ticks on contact
Odor-free
Long-lasting continuous release

What We Don't Like

A little tough to adjust

The Zodiac Flea and Tick Collar is our top choice for small dogs, featuring a slim design that won’t weigh them down. The active ingredient in this collar is tetrachlorvinphos, which kills and repels adult fleas and ticks, and it starts working on contact, providing full-body protection to your small pooch.

The Zodiac Collar can be used on puppies as young as 12 weeks old, and it's a mere 15 inches long, making it an appropriate size for smaller necks. Each collar is effective for up to seven months, and the water-resistant design can withstand getting wet occasionally.

Price at time of publish: $7

_{Sizes: One size, up to 15-inch neck︱Active Ingredients: Tetrachlorvinphos︱Effective Against: Fleas, ticks︱Duration: Lasts up to 7 months}

The 8 Best Flea and Tick Prevention Products for Dogs of 2023

Amazon

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What We Like

Whole body protection for large dogs
Effective against fleas and ticks at all life stages
Reflective outer coating

What We Don't Like

Collar may become loose or break off on dogs that like to play a lot

For larger dogs, the Adams Flea and Tick Collar is a popular choice, as it offers whole-body protection for even the largest breeds, fitting necks up to 26 inches. This collar uses tetrachlorvinphos and methoprene as its active ingredients, which allow it to kill more flea life stages—it’s effective against adult fleas, flea eggs, flea larvae, and it also kills adult ticks, tick larvae, and tick nymphs.

This flea and tick collar starts working on contact, and it provides protection for up to seven months. It’s water-resistant with a reflective outer coating for safety, and it has a notched design that ensures the collar stays in place, even on active dogs.

Price at time of publish: $7

^{Sizes: One size, up to 26-inch neck︱Active Ingredients: Tetrachlorvinphos, methoprene︱Effective Against: Fleas, flea eggs, flea larvae, ticks, tick larvae, tick nymphs︱Duration: Lasts up to 7 months}

The 7 Best Home Flea Treatments of 2023

Vetâs Best Flea and Tick Repellent Dog Collar

Amazon

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What We Like

Fresh, natural scent
Specially designed for dogs
Gives full body protection

What We Don't Like

Less effective overall

For an eco-friendly alternative to traditional insecticides, the Vet’s Best Flea and Tick Repellent Collar uses certified, steam-distilled, all-natural ingredients to repel all life stages of fleas and ticks. Using pleasantly-scented cedarwood and peppermint oils to deter pests, the collar itself doesn’t contain any toxic phthalates or PVC. However, anecdotal evidence suggests its overall less effective than flea collars that use traditional insecticides, especially in areas with a high rate of flea or tick infestation.

Water-resistant and adjustable, it works for puppies four months and older up to adult dogs with 20-inch necks. Each Vet’s Best Collar can be worn for up to four months.

Price at time of publish: $15

^{Sizes: One size, up to 20-inch neck︱Active Ingredients: Natural cedarwood, peppermint oils︱Effective Against: Fleas, flea eggs, flea larvae, ticks, tick larvae, tick nymphs︱Duration: Lasts up to 4 months}

The 4 Best Flea and Tick Treatments for Dogs

Final Verdict

Our top option for flea and tick control is the Seresto Flea and Tick Collar for Dogs, featuring a controlled release across your pet’s full body, works for up to eight months, and targets all pest life stages. If you’d rather go for a budget option, check out the Hartz UltraGuard Pro Flea and Tick Collar, which is affordable, adjustable, and water resistant.

Ingredients

To repel and kill pests, flea collars contain some type of insecticide, which is slowly released over your dog’s coat and skin. There are several insecticides commonly used for this purpose, including the popular combination of imidacloprid and flumethrin, as well as deltamethrin, tetrachlorvinphos, and more. Imidacloprid and flumethrin disorient insects, making them give up looking for food. Imidacloprid controls flea infestations while flumethrin works to kill and repel ticks.

Deltamethrin is derived from the chrysanthemum flower, and is safe for humans but toxic to fish and insects. Propoxur is toxic to humans and a variety of pests, including mosquitoes, fleas, moths, and more.

It’s important to note that any insecticide may cause an adverse reaction in your pet, with the most common being skin irritation. If this happens, you’ll want to remove the collar, flush the area with lots of water, and contact your vet for further guidance.

Duration

Most flea collars are designed to slowly release their active chemicals over a long period of time—typically between three and eight months. Naturally, the longer the collar lasts, the less frequently you’ll need to change it. However, it’s also important to consider whether the collar is water-resistant or -proof. If it’s not, the chemicals may be washed off if your dog goes swimming or gets caught in the rain, lessening the effectiveness of the collar.

Effectiveness

Riley-Wheeler notices a large number of patients come to them with flea infestations while wearing a flea collar. That said, there are brands that are more effective. These tend to be collars that have imidacloprid and flumethrin as primary ingredients, slow released over time. Riley-Wheeler also recommends oral flea prevention (these often include medicine for heartworm and intestinal parasite prevention) as well as topicals for effective flea and tick prevention.

Life Stage Targeted

Some flea collars are only effective against adult fleas, which is typically fine if you’re just using them to prevent future infestations. However, if you currently have a flea problem, you may want to look for a product that kills the bugs in more life stages, such as larvae and eggs—otherwise, you may have trouble breaking the life cycle of the insects.

FAQ

How do flea collars work?

Flea collars work by sending a continuous slow release of medicine into the animal’s dermis (coat and skin) that kills fleas and ticks on contact and repels them. It spreads over the whole dermis and continues working for a specified number of weeks or months.
Are flea collars safe?

While they are safe for the most part, flea collars are not suitable for all dogs. They’re typically only recommended for puppies 12 weeks and older, and they shouldn’t be used on senior, pregnant, or nursing dogs, either. Further, some insecticides can interact with other medications your dog may be taking, so you’ll want to consult with your dog’s veterinarian before using a new flea collar on them.
Do dog flea collars work on cats?

According to Riley-Wheeler, some flea collars can be used on cats, but you have to make sure they are specifically labeled for cats. She says, “Some of the IGR's (insect growth regulators) in the dog collars can cause neurological side effects in cats.“
How long do flea collars last?

Most brands last from three to eight months, so be sure to check packaging before purchasing. You should always change your dog’s flea collar after the time period recommended by the manufacturer. You may also want to put a new collar on your dog if you notice its effectiveness is decreasing.
Do flea collars kill fleas?

Yes, but it can take some time. Flea collars typically begin releasing chemicals as soon as they’re placed on your dog, and, in general, adult fleas should be killed within a few days. (This can vary depending on the product, so read the product packaging for more precise timelines.) However, it can take up to 30 days for a flea infestation to be eradicated, as flea eggs and larvae may still be lingering on your pet or in your home.

This article was researched and written by KJ Callihan, a writer for The Spruce, who has worked in animal shelters, helped socialize animals for adoption, and fostered animals of various kinds. She also writes articles of various kinds for CNET, AAA Northeast magazine, Finfrock Marketing, and more.

A previous version of this article was written by Camryn Rabideau, a freelance writer and lifelong dog owner. For professional guidance on flea collars, we also consulted Kristen Riley-Wheeler, a vet tech at Abbot Road Animal Clinic in East Lansing, Michigan.

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