Seresto Dog Flea and Tick Collar

4 out of 5 stars 4 Reviews | 66 Q&A

Seresto Large Dog Flea and Tick Collar (over 18 lbs)

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4 out of 5 stars Rating: 4

4 Reviews | 66 Q&A

Product Overview

The Seresto Dog Flea and Tick Collar provides a complete 8-month prevention and treatment of harmful parasites on your dogs and puppies. It specifically targets chewing lice, fleas and ticks that carry disease-causing organisms. Seresto exterminates ticks within 48 hours, wipes out fleas within 24 hours, and chewing lice for a month of initial application. The collar is certified easy-to-use, non-greasy and odorless. This collar features Polymer Matrix technology that is resistant to water. No need to remove this collar when bathing or swimming.

Available in 2 sizes:

  • Small dog - under 18 lbs.
  • Large dog - over 18 lbs.

It is recommended dogs or puppies 7 weeks of age or older.

Note: For cats, see Seresto Cat Flea and Tick Collar.

Features and Specs

Active Ingredient Imidacloprid - 10.0% Flumethrin - 4.5%
Target pests Fleas (including Larvae) and Ticks (including Deer Ticks, American Dog Ticks, Brown Dog Ticks, and Lone Star Ticks)
For use in Small Dogs & Puppies: 7 weeks or older for up to 18 lbs.
Large dogs: 18 lbs. and over
Application Insert end of the collar through the buckle
Adjust the collar around the dogs neck (able to insert two fingers between the collar and the neck)
* See Label for complete application instructions
Pet safe Yes, if used as directed on Label
Color Gray
Material / Construction Polymer Matrix
Special Features Non-greasy and odorless
Easy-to-use and provides 8 months protection
Shipping Weight 0.22 lbs
Manufacturer Elanco (Mfg. Number: B81857944)
UPC 724089579447
EPA Registration 11556-155


About Fleas and Ticks

Fleas and ticks are more than just annoying. They can cause several health issues.


A single flea can feed on your pet for over 3 hours.

Fleas can also lead to potentially serious health risks:

  • Skin problems
    Flea bites can cause flea allergy dermatitis (FAD), an allergic reaction that can lead to constant scratching, severe itching and hair loss.
  • Intestinal parasites
    Ingestion of an infected flea can transmit tapeworms, one of the most common intestinal parasites seen by owners.
  • Anemia
    May occur with severe flea infestations. Heavy flea infestations can even cause death.

Fleas are not just a “dog problem”

You or your dog can bring fleas home to infest your cat without you realizing it. This, plus any outside exposure can put a cat at risk for fleas.


Repelling and killing ticks is important:

The mouth parts of a tick act like a tiny harpoon, ready to anchor into the dog or cat's skin. After they are attached and are feeding a number of organisms can enter a dog or cat's bloodstream. If a tick is repelled or killed, it cannot attach and transmit organisms that may cause disease.

  1. When a tick attaches to your dog or cat, it cuts blood vessels under the skin, causing blood to pool.
  2. Tick saliva contains an anticoagulent to keep the blood pool from clotting.

Ticks may also carry organisms that can cause:

  • Lyme disease
    Lyme disease is caused by the bacteria Borrelia burgdorferi, and may take less than 24 to more than 48 hours from the time the tick feeds to infect the host. Most infected dogs do not develop clinical disease, but if they do signs may include: inappetence (or anorexia), arthritis, fever and swollen lymph nodes. In some cases, this disease can lead to kidney failure.
  • Rocky Mountain spotted fever
    Rocky Mountain spotted fever is caused by Rickettsia rickettsii. It can be contracted 4–48 hours after being transmitted.4 Clinical signs include: lethargy, anorexia, fever, vomiting and bleeding disorders.
  • Ehrlichiosis
    Generalized transmission time for Ehrlichia bacteria is 4-48 hours. There are several types of ehrlichiosis, but symptoms in dogs can include: fever, depression, lethargy, loss of appetite, weight loss, enlarged lymph nodes and abnormal bleeding, such as nose bleeds.
  • Cytauxzoonosis
    This cat-specific disease can kill cats within one week of the first symptoms. Treatment is rarely successful. This disease is transmitted by ticks, which is why repelling and killing ticks is important. Learn more about cytauxzoonosis here.

How Seresto works

An effective combination

Inside the unique polymer matrix of Seresto are two active ingredients:

  • Imidacloprid has been used in products recommended by veterinarians for years to control flea infestations.
  • Flumethrin effectively repels and kills ticks, and kills larvae and nymphs.
  • Flumethrin works together with imidacloprid to provide dual action against fleas and ticks. No other treatment has this combination of ingredients.
  • The active ingredients spread from the site of direct contact over the skin surface of the cat or dog.

Sustained release technology

Seresto works similarly to a monthly topical, but as the active ingredients wear off over time, a new supply is continuously replenished in low concentrations. The active ingredients spread from the site of direct contact over the skin surface.

Bayer's polymer matrix technology is designed to slowly and continuously release the active ingredients over eight months, a duration that makes it clearly different from other collars.

Seresto is water resistant

The active ingredients of Seresto are contained within the Bayer Polymer Matrix, making it water-resistant. Therefore it is unnecessary to remove the collar before the pet is immersed in water. Seresto remains effective following a shampoo treatment, swimming, or after exposure to rain or sunlight. Under normal conditions, effectiveness lasts for eight months. In order to maintain an 8-month duration, dogs must not be bathed more than once per month. For dogs that swim once a month or more, the control duration is reduced to five months.

How to Apply

Monthly flea and tick treatments can be time-consuming to apply. Plus, remembering to apply them monthly can be a hassle. Seresto takes just minutes to adjust on your dog or cat, and provides treatment that lasts eight months against fleas and ticks.

Application is easy

  1. Remove collar from protective bag immediately prior to use.
  2. Unroll collar and make sure that there are no remnants from the plastic connectors inside the collar.
  3. Insert end of the collar through the buckle. Adjust the collar around the dog or cat’s neck without tightening it too tight (as a guide, it should be possible to insert two fingers between the collar and the neck).
  4. Pull excess collar through the loop(s) and cut off any excess length extending 1 inch (2 cm) beyond the loop(s).
  5. Seresto comes with three optional reflector clips that can be attached to the collar for additional visibility at night. The reflector clips should be evenly distributed on the non-overlapping part of the collar.

Make sure Seresto fits securely

As a guide, it should be possible to insert two fingers between the collar and the neck. Make sure the collar is not loose enough for the cat to put its leg through.

If your dog or cat is not used to collars

Please carefully observe your dog or cat when it’s wearing a collar for the first few days, especially when the pet is not used to wearing a collar. Try using a tasty treat, toy or other activities to distract your dog or cat’s attention from the new collar. Occasionally slight itching may be observed in animals that are not used to wearing collars in the first few days of fitting. Ensure that the collar is not fitted too tightly.

Safety-Release Mechanism

Because some pet owners may be concerned that a cat or small dog could get stuck while wearing a collar, Seresto is designed with a safety release mechanism. In the unlikely event of the cat being trapped, the cat's own strength is sufficient to widen the collar to allow for quick release.

A hard pull causes the ratchet-release mechanism to allow a widening of the collar.

The small dog and cat collars are equipped with a predetermined breaking point. A harder pull triggers the breaking of the collar at this point.

If your cat is not used to collars

If the collar feels foreign, the cat especially may scratch at it initially but should adapt in time. Offering a treat or toy after applying Seresto may be enough of a distraction to end this behavior.

Slight hair loss and mild skin reactions due to the mechanical irritation of the collar may occur at the application site, which usually recover within a week or two without the need for collar removal.

Note: Please see Product Label for important Precautionary Statements and proper Storage and Disposal.

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Sort Reviews
  • 5 of 5 Stars

    Excellent Product!

    By Laurie on 01/10/2017

    I have two dogs and three cats and always had a problem with fleas, especially during the summer months. These flea and tick collars are amazing. Doesn't seem to matter where they wonder, all of my pets have been flea-less since using. And it does last for at least 8 months. Best flea prevention I have ever purchased.

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    20 of 20 people found this review helpful

  • 5 of 5 Stars

    Flea Control

    By Floyd on 05/10/2018

    Best product out there. Never really cared for collars but after trying the popular drops with no success, I was recommended to try this product. After a couple of days the dogs quit scratching. Amazing product

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    9 of 10 people found this review helpful

  • 5 of 5 Stars

    Flea problem

    By Linda on 04/10/2020

    Our three dogs went to the vet for vaccinations and came home with fleas. Frontline Plus proved to be inadequate for the job, but the Seresto collars, along with spraying have taken care of it.... I think.

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    5 of 5 people found this review helpful

  • 1 of 5 Stars

    Made my dog VERY sick - Do NOT use this

    By Yvonne on 07/09/2023

    My dog began vomiting and diarhea from this collar. Do NOT use this collar. After removing, and bland diet, she is recovering.

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Questions & Answers

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Does the Seresto Dog Flea and Tick Collar have an expiration date if not opened?

The Seresto Dog Flea and Tick Collar does not have an expiration date as long as it has remained in its original container and stored in cool/room temperature conditions.

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358 of 410 people found this answer helpful

Could using a large Seresto Dog Flea and Tick Collar on a small dog cause harm?

Seresto Dog Flea and Tick Collar

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239 of 250 people found this answer helpful

Can I bathe my dog with the Seresto collar on,without decreasing effectiveness?

According to the

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150 of 159 people found this answer helpful

How long does it take for the tick to die with the Seresto Dog Flea and Tick Collar if it attached?

It takes 24 hrs to kill existing fleas and 48 hrs for ticks with the

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139 of 163 people found this answer helpful

We sleep with our dog. Should we take the Seresto Dog Flea and Tick Collar off at night time?

There is no need to remove the Seresto Dog Flea and Tick Collar

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106 of 123 people found this answer helpful

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