Comprehensive Seresto Flea Collar Review: Is It Effective Enough?

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Chances are high that, if you have a furry friend, you’ll find ticks and fleas paying you a visit more often than you’d like them to. Although extremely common, these tiny pests are still capable of causing trouble.

While both types of parasites are harmless as such, they pose a risk to our health and that of our pets by potentially causing secondary infections. With fleas, the list includes typhus, flea-borne spotted fever, and plague. Tularemia and Lyme disease are some illnesses carried by ticks.

To make things worse, some people have an allergy to flea bites, while others might develop hypersensitivity when bitten by a tick.

This being said, buying a flea collar like Seresto to keep the parasites off your fluffy companion might sound like the perfect solution, but how does a Seresto flea collar work, and is it actually safe?

Detailed Seresto Flea Collar for Dogs and Cats Review

Seresto is a brand name that covers a line of anti-flea pet collars. In this article, I’ll be sharing my impressions of two varieties, namely the model targeting large dogs and the one designed for cats. Please mind that there’s a specialized option for small dog breeds as well.

The collar is manufactured by the Animal Health division of Bayer, a German pharmaceutical company and one of the global market’s leaders in the area. While the well-reputed business dates back to as early as 1863, it didn’t deal with pet health until 1919. Neguvon was launched at that moment, marking the beginning of the flea control series.

As a pet owner, you’ve probably heard the name of Advantage more than once – this flea treatment has been extremely successful for over two decades now.

Seresto for Large Dogs (And What is a Seresto Collar)


  • Active Ingredients: Flumethrin* 4.5%, Imidacloprid 10.0% (*Trans Z-1/trans Z-2 Ratio: max 66% trans Z-1 and min 34% trans Z-2)
  • Age Range Description: All Life Stages
  • Item Weight: ‎2.08 Ounces
  • Product Dimensions LxWxH: 4.75 x 4.75 x 1.5 inches
  • Target Pests: Flea, Tick

Seresto Flea and Tick Collar for Dogs

The product under review is a flea treatment based on imidacloprid (10%) and flumethrin (4.5%), both effective insecticides but of different origin, that’s formulated into a collar to be put around the pet’s neck for tick and flea control.

The former active ingredient, imidacloprid, is a representative of the relatively new insecticide class called neonicotinoids. Built to mimic nicotine in many ways, it acts by interfering with sucking parasites’ nervous system.

The latter, flumethrin, belongs to pyrethroids, which are man-made pesticides resembling the naturally occurring pyrethrins that can be found in certain daisy varieties. They also affect the insect’s nervous system, causing paralysis and ultimately death upon contact.


The practice of combining two or more insecticides within one formulation is quite common and is viewed as a synergic blend where one ingredient enhances the effect of the other.

What you get with Seresto is a formula that doesn’t require fleas and ticks to actually bite your pet to kill and deter them by releasing low concentrations of the pesticides into the animal’s coat.

Unlike most other formulations such as sprays and shampoos, this solution will last for up to 8 months provided that your dog doesn’t bathe too often (if so, the manufacturer recommends reducing the application period to five months in terms of flea control).

Apart from killing mature fleas and ticks, the Large Dog version of the collar is active against sarcoptic mange carrying mites and lice. It will probably take up to a full day to kill existing fleas, while those trying to re-infest later normally get exterminated within two hours (according to the manufacturer’s description of Seresto® for Dogs).

Indeed, you’ll start seeing dead fleas from head to tail very soon. I’ve found the collar to be extremely efficient in killing existing parasites as well as preventing their kind from ever coming back over the entire 8-month period.

My grade: 5/5


This is one thing that almost every Seresto flea collar review mentions, and I must admit it’s true – this is not an inexpensive treatment. However, by investing around forty to fifty dollars you’ll hopefully solve the problem of tick and flea control for a whole 8 months, which makes it well worth the money.

My grade: 4.5/5

Ease of Use

Most Seresto dog collar reviews celebrate how easy this treatment is to apply and how long it lasts, sparing you a series of potentially messy re-applications that you’d normally need with flea shampoos and sprays.

What you need to do is put the collar around the animal’s neck and leave it on. It doesn’t necessarily prevent you from using a regular ID or restraining collar if you want to. I also appreciate the fact that Seresto doesn’t feel greasy or sticky and has no chemical odor.

Luckily, the collar is resistant to water as well as sunlight, so it can be combined with shampoos on a monthly basis or more rarely.

My grade: 5/5


This product is recommended as safe for dogs from 18 lbs and cannot be used to treat other animals.

The formula used to kill parasites in this collar is absolutely safe to humans of any age, including babies, but contact with exposed skin should be avoided. The general advice is to wash your hands whenever you touch the collar and make sure that your children don’t grab it while playing with the pet.

Allergic reactions to Seresto collar have been reported occasionally. However, it’s important that you understand that any pesticide has the potential to cause individual hypersensitivity. It’s still advisable to monitor the animal’s coat for signs of irritation while using the collar. The manufacturer specifies that scratching is possible at the early stages, especially if the pet isn’t used to wearing a collar, which doesn’t require any action.

My grade: 4.5/5

Overall product score: 4.7

  • Kills fleas, lice, and ticks effectively;
  • Prevents re-infestation over 8 months;
  • Easy to use;
  • No need to re-apply;
  • Safe around children.
  • Not the most affordable treatment.

Seresto for Cats


  • Active Ingredients: Imidacloprid 10.0% Flumethrin 4.5%
  • Age Range Description: All Life Stages
  • Scent: Odorless
  • Item Weight: 0.22 Pounds
  • Product Dimensions LxWxH: 4.75 x 4.75 x 1.5 inches
  • Target Pests: Fleas, Ticks

Seresto Flea and Tick Collar for Cats, 8-month

Since this product is essentially identical to the Large Dog version except in details, I’ll only dwell on what’s different while referring to the above review for the information that applies to the Cat and Large Dog versions alike.


While the formula and release mechanism are the same, the manufacturer doesn’t claim any anti-lice effect for cats. The collar is still extremely effective in terms of flea and tick control.

My grade: 5/5


About the same as above.

My grade: 4.5/5

Ease of Use

The same as the above.

My grade: 5/5


Your cat should be at least 10 weeks of age to wear the collar. Seresto cat flea collar side effects and safety considerations are otherwise the same as with the Large Dog version.

My grade: 4.5/5

  • Kills fleas and ticks effectively;
  • Ensures 8-month prevention;
  • Easy to use;
  • No need to re-apply;
  • Safe around children.
  • Somewhat pricey.

Overall product score: 4.7

Buyer’s Guide

In this section, I’ll tell you how to make the right choice when shopping for a cat or dog flea collar and share with you the key signs that will prevent you from buying a fake for the price of an original product. I’d also like to share my experience of combining treatments like Seresto with other formulations for optimum effect.

First of all, you need to know the parameters to search by while looking for a flea control collar. Since this is a common formulation on the market, a lot of options exist to fit any budget.

While certain products are labeled as safe for cats as well as dogs, it’s general practice to produce specialized feline or canine collars instead. Some brands also offer additional models for young animals, usually containing a lower dose of the active ingredients.

If you are concerned with potential Seresto collar side effects on your kitten or puppy, make sure that the animal is old enough to be given the treatment. The minimum acceptable age or, alternatively, bodyweight should be specified in the label and/or instructions for use.

It’s also important to re-fit the collar often enough as your furry companion grows to avoid excessively tight fit and possible damage to the coat or skin. Seresto cat collar reviews attach special importance to this since kittens tend to grow quickly.

While killing existing parasites can be a challenging task as such, it’s prevention that actually determines success in the long run. This has to do with the different life stages that bloodsuckers go through within their lifecycle. Talking about fleas, these include egg, pupa, larva, and adult flea states, each requiring special treatment as compared to others.

There are formulas that kill immature fleas and ticks, potentially rendering re-application unnecessary provided that you’ve put through a meticulous anti-flea cleaning campaign, while others need to act continuously or periodically in order to prevent re-infestation.

Most collars claim to have a sustained deadly and/or deterrent effect on insects throughout the use period, dealing with new fleas as they arrive. This is exactly the case with Seresto. However, additional prevention methods as welcome in cases of originally heavy infestation or if you live in an area that seems to inevitably attract fleas.

These preventative treatments can include home flea sprays, mostly used to expel the parasites from where they’ve taken residence, and shampoos. The latter act on contact, most commonly also by interfering with the pests’ nervous system, and can be very effective when the infestation is really massive.

One downside of shampoos is that the whole procedure tends to get messy, with the animal trying to lick the not-so-safe formula off its fur and wriggling as you wait for the lather to work.

Luckily, monthly bathing is generally enough for adequate flea prevention. This also means you can combine it with Seresto collars since Bayer specifies them to be water-resistant provided that the dog or cat doesn’t take a bath more than once a month.

Alternative Products

I have compared Seresto collars to a number of flea treatments that are advertised to have a similar effect and are also a popular choice to find out which works the best and whether Bayer’s products are worth the price tag that they come with.

These included an alternative dog collar by Adams, another well-established pet care brand, and two Bayer formulations that can be used either instead of or in addition to Seresto. Here’s what I’ve found out.

Seresto vs Adams


  • Water-Resistant
  • Age Range Description: Puppy
  • Item Weight: ‎0.05 Pounds
  • Product Dimensions LxWxH: 0.88 x 4.25 x 4.13 inches
  • Target Pests: Fleas, Ticks, Flea Eggs and Flea Larvae

The two collars might seem very similar when you read about them on a store’s page. Both target dogs and both are claimed to ensure prevention for months (7 in a row with Adams) while also killing existing fleas and ticks, including larvae.

However, the Adams collar is way more modestly priced as compared to Seresto. In fact, the former is one of the most budget-saving options you’ll find on the market. The question is, does it affect performance?

Unlike Seresto, which relies on a combination of imidacloprid and flumethrin, the Adams dog collar formula is based on tetrachlorvinphos (14.55%).

The first thing you notice when you have the two products side by side is that the Adams collar has a strong chemical odor, while Seresto is completely neutral in this respect. While both products have the potential to cause side effects such as skin irritation, those experiences with the latter seem to be milder judging by the reviews.

However, the main difference between the two collar brands lies in effectiveness. I’ve found Adams to take a lot longer to kill existing fleas (about two weeks as compared to a full day) and to last way under the 7 months that it’s advertised for. In fact, chances are that you’ll see fleas returning in about half the time if it’s flea season in your area.

This said, I highly recommend investing in Seresto rather than taking chances with the more affordable Adams options, especially if you’re suffering massive flea infestation.

Seresto vs Advantix


  • Active Ingredient: Permethrin
  • Item Form: Drops
  • Age Range Description: All Life Stages
  • Item Weight: ‎0.15 Pounds
  • Product Dimensions LxWxH: 7.75 x 1 x 4.25 inches
  • Target Pests: Flea, Tick

K9 Advantix II Flea and Tick Prevention

Based on imidacloprid, permethrin, and pyriproxyfen, Bayer’s K9 Advantix is formulated into easy-to-use drops for monthly treatment. It stands out among competitor products due to its ability to deter mosquitoes and biting flies as well as fleas and ticks, which can be an advantage if these little whining pests seem to be plaguing your dog.

When compared to Seresto, K9 Advantix is not nearly as short-lived, only offering protection for one month. However, it can be used in combination with the collar when for extra protection if your area has a lot of bloodsuckers or for the additional benefit of repelling flies and mosquitoes.

Concomitant use is absolutely safe provided that you follow the directions, and the drops don’t take as much time to apply as shampoo. All in all, it is a relatively mess-free topical formulation that does work, although for a limited time.

Seresto vs Advantage II


  • Active Ingredients: Imidacloprid 9.10% Pyriproxyfen 0.46%
  • Age Range Description: Adult
  • Item Weight: ‎0.8 Ounces
  • Product Dimensions LxWxH: 6.5 x 1 x 4.25 inches
  • Target Pests: Fleas, Ticks

Advantage II 6-Dose Large Cat Flea Prevention

Just like the product above, Advantage II is a monthly topical flea treatment, the only difference being that it targets cats (large, small, or kittens, depending on the version). With imidacloprid (9.1%) and pyriproxyfen (0.46%) as its active ingredients, the product acts within 12 hours from application, offering a lingering effect for about 1 month.

As with K9 Advantix for dogs, you can use the topical formulation to speed up the process in case of massive infestation or flee season while also using a collar or use it alone with monthly re-application. It works against all life cycle stages of the flea throughout the specified period and is relatively easy to use, with no need to wet and lather the animal.

Real vs Fake Seresto Collar

While purchasing a Seresto collar from your veterinary practice or a local pet store might be the safest option when it comes to avoiding fakes, I do realize that many people prefer shopping on the web.

If this is the case with you, my suggestion is to use official Bayer partners or the company’s Amazon page and to inspect the product upon arrival to make sure that it’s not a counterfeited article. Remember that using fake pet care goods, in particular collars, can result in damage to your animal’s health or that of people around, which is not to mention possible failure to act and inefficiency.

Here are some tips on how to tell an original Seresto collar from a fake.

  • Look at the packaging.

Original Seresto collars always come in tins measuring 12 cm (4.7 inches) across, with a well-printed sticker on the back. The background color of this sticker will differ depending on which version you purchase, but print quality is key. If you see typos and “fuzzy” letters, this is a sure sign that you’re dealing with a fake.

It’s also common for fake collars to come with a single round sticker securing the tin, while original products will be wrapped all-around to prevent any tampering.

The inner surface of the tin is also colored according to the animal of choice. On the front side, there should be an embossed Seresto logo rather than a printed one. This means you should be able to feel it as raised over the general surface with your fingers.

Finally, and most importantly, the tin must have the lot number and the expiry date clearly indicated on it. “Do Seresto collars expire?” is one question that people often ask if they happen to purchase is fake. With an original Buyer product, however, you’ll always know how long you can use it.

  • Look at the collar

When you open the tin, the collar inside should be packed in a plastic bag with some text on it, featuring legal information and the company’s logo. A 100% clear bag clearly indicates that what you’re holding is a counterfeited product. Besides, a leaflet is included in the tin to provide you with detailed information on the collar.

You can always tell a real Buyer Seresto by its lock as it boasts a specially designed sliding release system rather than a common buckle, which is often the case with fakes. It also has a raised ridge along its entire length and a small logo printed on it.

You should also make sure that there is a lot number on the side of the collar, which must match the one on the tin, while it’s common for fakes to have none at all.

Finally, it’s absolutely unacceptable for the collar to smell, which might seem somewhat counterintuitive but, in fact, adds to the usability and helps distinguish between fakes and original products.


In this section, I answer some of the most popular questions about Seresto collars and how to use them. Feel free to post a comment if you still have any doubts.

How Long Do Seresto Collars Last?

According to the label, Seresto collars will last 8 months unless your animal is a frequent bather, in which case the period is reduced to 5 months for flea control. The product features a sustained release technology to ensure non-fading performance throughout the period and is generally water-resistant, though prolonged repetitive shampooing should be avoided.

How Long Does It Take for Seresto to Start Working?

Bayer states that existing fleas are killed within the first 24 hours after application. Once your pet has been wearing it for a full day, re-infestation might occur, but new insects will generally die within 2 hours. As for ticks, the numbers are different. The collar kills those already present within 48 hours, while it takes about 6 hours to deter or exterminate new ones.

How Do I Remove a Seresto Collar?

Since Seresto collars are resistant to water as well as occasional shampooing, there’s no need to remove them unless you want to stop using the product or replace it with a new one. You can simply cut it with scissors or, alternatively, squeeze the outer sides of the safety release lock while pulling from the other end.

Is Seresto Safe for Humans to Touch?

It is, but it does require precautions such as washing your hands afterwards. The risk of toxicity is relatively low since it’s the grease in a pet coat that normally helps to spread active ingredients. Besides, the formula is generally safe for humans, but allergy is a possible reaction to a Seresto collar.

Summing It Up

“Does Seresto work?” is probably the key question that potential buyers would like to find an answer to. It is, and it does so for the whole term of 8 months that’s claimed in the ads. That is, in a Seresto vs Frontline battle, the collar wins as a more long-lasting treatment than any topical formulation.

I also appreciate the fact that it’s safe to use around children and doesn’t make playtime with your pet too much of a challenge.

Overall, Seresto is an excellent line of effective, easy-to-use flea collars superior that I’ve found to be to the most popular competitor products. It’s safe to say that a higher-than-average price is its only considerable disadvantage.
Have you ever tried cheap flea collars and been disappointed? Please share it in the comments section down below!


  • Illnesses from Mosquito, Tick, and Flea Bites Increasing in the US (U.S. Department of Health & Human Services):
  • Neonicotinoids(Official Website of The City of Austin):
  • Seresto for Dogs (ElancoDVM):


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Nicholas Martin

Nicholas Martin

I am Nicholas Martin, and I am an entomologist. I combine the insect survey work with the consultation for private pest control agencies. My narrow specializations are both urban pests and agricultural pests. I studied their control over the previous 25 years. More about Nick

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