Do Seresto Collars Work? – Our Review

do seresto collars work
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When we brought home our rescue kitten he was absolutely covered in fleas, to the point where he had scabs all over his skin from where he had been bitten, over and over again!

I tried multiple big box store brand flea treatments and flea baths, but nothing seemed to get rid of them. These fleas were persistent, but after a lot of frustration, I finally happened upon the Seresto flea collars.

So, Do Seresto Collars Work Against Fleas?

It certainly did. This was the best flea treatment I tried, and also the easiest one to use! While it is one of the pricier flea treatments on the market, it definitely works.

The collar is a lot easier to use than topical treatments which are messy and end up on their fur half the time too. You’ll also only need to replace the Seresto collar every 8 months rather than every 3 months as with topical flea and tick treatments. Click here to check prices on Seresto collars.

Warning! Watch Out For Counterfeit Seresto Collars On Discount Sites!

While it’s tempting to purchase one of these collars on eBay or some other discount site to save some money, you should be very careful doing this. There are a lot of fake collars going around that can make your pets very sick. If the price is too good to be true, there’s a reason.

Real vs Fake Seresto Collars

Video: Real vs Fake Seresto Collar – How To Tell The Difference

The above video shows you how to spot counterfeit Seresto collars. While the boxes look similar, there are noticeable differences you can see when you compare them.

Counterfeit medications are big business for scammers, even for medications for humans! However, you should make no mistake. These are not the same, and these people do not care about your cat’s health.

If you want to make sure that you get a real Seresto collar, then you should buy it from an official retail partner. I recommend getting your collar from Chewy, because the are an official partner.

Note: Be careful of buying these collars on Amazon. Even if it says “shipped by Amazon” their merchandise is mixed with other sellers who may be using Amazon’s warehouse to ship counterfeit merchandise!

How is this different from other collars?

I was skeptical of this product at first. Flea collars are notoriously bad treatments, and many of the ones at your local store are just plain misleading in what it is they do. The reason that most collars make such poor treatment is because some of them don’t even kill fleas at all!

Many of them actually just repel the fleas, so they still hang around your house. The effective range may also be limited to the immediate area of the collar. So as long as the fleas avoid it, they can continue to live, and that makes most flea collars basically useless if you’ve already got a flea problem.

seresto collar faq
Unlike other flea collars, Seresto kills fleas on contact rather than just repel them.

Seresto collars actually have properties that kill fleas and ticks. The active ingredients in the Seresto collars are imidacloprid and flumethrin, and since there is a continuous stream of these ingredients being produced it does not give the fleas a chance to lay new eggs, because the adults will die before that ever happens.

This is the only way to break the life cycle and truly be rid of your fleas. I wasted a lot of time with other treatments before getting this collar. It’s worth every penny, and I’d have saved a lot of money if I’d just bought Seresto first.

Is Seresto better than spot treatments?

I had been using the type of flea medication that you put on the back of the cat’s neck previously, but it seems to have stopped working. Perhaps the fleas in our area have built up an immunity to it, but it was not doing the job. I tried two or three of them and some flea pills to no avail before picking up the Seresto collar.

The Seresto is still better in another regard, even if the spot treatment did work. In order for those skin treatments to kill fleas they typically have to bite the animal. This is obviously distressing for your cats and dogs, because it’s painful! With the Seresto collar, the fleas are killed on contact, and it’s a much less stressful experience for your pets.

How does the Seresto flea collar work?

The Seresto collar works by killing fleas on contact. After placing the collar on your dog or cat, any fleas that are on them will die instantly upon touching your pet. It starts to become effective within 24 hours.

Other flea treatments, such as the ones that must be ingested or be absorbed through the skin actually require the fleas and ticks to bite your cat or dog before they are effective!

does seresto kill flea eggs
The Seresto collar releases a steady stream of active ingredients which kill fleas on contact.

This is obviously not ideal. Flea bites are painful, and this can lead to serious distress for your dog or cat when suddenly hundreds of fleas are eating them alive.

It also means that these treatments don’t actually protect your dog or cat from the plethora of illnesses that can be carried by fleas and ticks. By using the Seresto collar, you can kill the fleas without the risk of your pet being infected.

These Bayer flea and tick collars slowly release the ingredients in low dosage amounts over an 8 month period. These chemicals distribute themselves over the animal’s hair and skin surface, which is what makes this particular treatment so effective.

Seresto Collar FAQ

Does Seresto kill flea eggs?

Technically, no it does not. However, the Seresto collar will remain active for the duration of the flea’s life cycle. This actually prevents them from being able to lay eggs at all! As soon as the new fleas hatch, they will die.

How long does Seresto take to work?

Seresto collars will begin working immediately, but you will see fleas for a while after putting it on your cat. In order to get rid of the fleas you have to get through the fleas life cycle. It could take 2 days to 2 weeks for the remaining eggs to hatch and for those fleas to be killed.

Seresto collar is on but cat/dog still has fleas!

Is your Seresto collar not working on fleas? You should refer to the above FAQ section. It could take a couple of weeks for the fleas to be completely gone. This is because you have to go through the whole flea lifecycle. Once the eggs hatch, they will begin to die immediately.

Where Can I Get The Best Price on Seresto collars?

Amazon generally has good prices, but not everyone there is an official seller. If you’re worried about getting a legitimate collar – then getting one from a local store or Chewy is probably the best bet.

Where are seresto collars made?

Seresto collars are made in Germany.

Are seresto collars made in china ever?

No, if your collar says that it is made in China, it is a counterfeit. You should return it, or throw it away if that’s not possible. Using it on your pet could be dangerous to their health.

Can Seresto Collars Get Wet?

The collar can get wet, but it might be better for you to take it off of your pet before bathing them or letting them go swimming. According to the manufacturer, letting the collar get wet can reduce the lifespan of the treatment, and you’ll likely need to buy a new one sooner. You could cut as much as 5 months off the life of the collar if you let it get wet too often.

Do You Take Seresto Collar Off For Baths?

If you bathe your dog frequently, then it might be best to do so. While the collar can get wet, this can reduce the effective lifespan of the collar if you do it too much.

Can you take the seresto collar off at night?

It is possible to remove Seresto collar at night. However, it’s kind of a pain to do it, and it’s not really necessary. In fact, removing it too often might negatively impact its performance.

How to remove Seresto collar

Start by squeezing the outer sides of the buckle on the collar. At the same time, pull from the other end or side of the collar. If you’re planning to replace the collar, it’s honestly easier to just cut it off though.

Can I use seresto and frontline together?

The answer to this one is hard to say. Some people say it’s fine, and others advise against mixing medications. The truth is, it might depend on how sensitive your dog is to medications.

If you do attempt it, watch your dog very carefully for any adverse reactions. Discontinue use immediately if you notice any odd behavior.

Seresto Cat & Dog Collar Warnings and Complaints

There are a good number of Seresto collar complaints online. The truth is, any medication poses a risk to both animals and people. Some animals are sensitive to certain medications or treatments.

Our cat suffered no ill effects from wearing the collars, but yours might. Every animal is an individual, and they can have allergic reactions just like people can.

That’s why it’s very important that any time you start using a new medication or treatment on your pets that you monitor them for some time after.

seresto cat collar adverse reactions
Pictured: Seresto cat collar adverse reactions

We would recommend checking your animal every day for at least a couple of weeks when you put the collar on them. If you start to see any redness on their neck or if the skin looks raw then this is not a good solution for them. Discontinue using the collar and look for something that is less harsh or does not make contact with their skin.

Seresto Dog & Cat Collar Side Effects

There are some side effects to the Seresto collar that you should be aware of. If your pet is sensitive to topical treatments or chemicals of any kind then you should look out for these things. If you see any of these symptoms present in your pet then discontinue the use of the collar immediately.

Possible Seresto collar side effects cats & dogs

  • Raw skin
  • Chemical burns
  • Diarrhea
  • Vomiting
  • Swelling
  • Lethargy

The Seresto collars contain an active ingredient called flumethrin. This is an insecticide, but it is also mildly toxic to mammals. In many cases, these side effects are believed to have been caused by pets who have licked the collar.

This can, unfortunately, be a challenge with multiple pets for any flea treatments as they have a habit of grooming each other. A dog or cat licking Seresto collars will likely start feeling very ill. You might need to find another solution for them if this becomes a problem.

What can I do if my pet reacts badly to Seresto?

While the collars do work well, there will unfortunately be some pets who can not use them. If you have an animal that seems to be particularly sensitive to many things, then this may not be the best choice.

Best Seresto Alternatives

For pets with severe allergies there are a couple of other options that you could consider. I have not tried all of these, but if you have a sensitive kitty or doggy, try these Seresto alternatives.

Capstar flea pills

If your pet has sensitive skin and can not handle topical treatments then these pills do kill fleas very quickly. It could also be a good solution if your pet has a bad habit of licking topical treatments off of your other pets.

The only problem is that this is not a continuous use product. This pill will kill all the fleas that are currently on your dog or cat immediately. However, it will not kill the eggs or any new fleas that hatch after those ones die.

You’ll need to treat your entire house with something that will kill any eggs that may be hiding in your carpets, and then repeatedly give the pills to your pet until the life cycle of the fleas has been broken.

This did work for killing our fleas once, but our cat got re-infested, and then we went with the collar. This is however one of the few treatments that does not require skin contact, and if he had any skin sensitivities we would probably go back to this treatment.

It’s a great product as long as you understand how it works. If your pet is an indoor only animal and you can keep new fleas from getting in your house, then this could be a good solution for you.

If you have a pet that frequently goes outside though, then you likely will just get re-infested. If your animal is sensitive to topical treatments you could try to keep fleas away by spraying the house instead of putting treatments directly on your pet in combination with this pill.


If you need a completely natural product to help your pet battle fleas and ticks, then CedarCide is a solid option. It’s a totally natural spray product, and unlike other all natural items it does not contain any ingredients which are harmful to cats and dogs.

Other products in this category often use citronella or peppermint, both of which can make dogs and cats very sick if they eat them. Instead, Cedarcide uses cedar oil. This ingredient is harmful to pest insects such as fleas, ticks and mosquitoes, but it has no effect on humans, dogs, cats or even beneficial insects like bees and butterflies.

While it is very effective in both repelling and killing these problem insects, it is slightly less convenient. You’ll need to continuously spray your pets with it, unlike the Seresto collar, which protects your animals for 8 months at a time.

If your animal is sensitive to chemical treatments though, this is a solid alternative and it’s worth a try. Plus, you can even use it to treat your house and your yard to keep all kinds of pests away!


While the Seresto collars did very well for us, pet parents should try to remember that their pets are individuals. They have sensitives and preferences just like humans do. There’s no one size fits all solution here, and the best flea and tick treatment is the one that works for your dog or cat.

We’ve tried our best to offer some insight here to help you make a decision, and these alternatives are meant to help struggling pet parents who may have trouble using the collars if their pets are allergic to them.

While we would’ve liked to recommend another collar, most of the all natural alternatives leave much to be desired. They either don’t work well or they use products which would just make sensitive dogs and cats sick anyway.

For that reason, we believe the Cedarcide and the Capstar pills are the best choices for sensitive pets who can’t use Seresto collars without experiencing bad side effects.

Michelle Rei
Michelle Rei
Michelle is a pet parent turned amateur pet product researcher. After adopting a fur baby with digestive issues caused by bad pet food, she's poured hundreds of hours into research to find the best of the best to help him and other pets live happier and healthier lives.
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