Seresto Reviews | The Complete Guide (Including Side Effects)

We did plenty of research before completing our review of Seresto Dog Collars. In particular, we wanted to make sure this is a safe product before recommending it to our readers.

Quick Stats

Seresto Flea & Tick Dog Collar

  • Suitable for dogs 7 weeks or older
  • Killsfleas and ticks
  • Prevents flea eggs from hatching, interrupting the life cycle
  • Water resistant
  • 8 months protection
  • Delving into the research we found that over 20,000 reviewers from leading online retailers gave Seresto Collars and average of 3.8 stars, for something as important as flea and tick control this could be of some concern.

    We did find some anecdotal reports from some folks online about the safety of this product, however, we also found similar reports for other pesticide-based flea and tick control products.

    Dr Sara Redding Ochoa | Doctor Of Veterinary Medicine

    Sara is Wileypup’s Veterinarian Adviser and helped compose this article to ensure the information is up to date and accurate. For more information on Sara click here

    Want to know the truth?

    A small number of dogs can have hypersensitivity to certain chemicals, and pesticides are known to sometimes trigger extreme reactions.

    Instead of deciding for you if Seresto Collars are safe, we tried to present some resources and information that you can trust so that you can make the right decision along with your vet for what is going to work best for you and your dog.

    We did, however, find lots of confirming evidence from customers, veterinarians and independent research studies that the product is effective.

    On this score, unless your particular geographic area has already developed resistance to this product, Seresto Flea and Tick Collars are very likely to be an effective way to treat fleas and ticks on your dog.

    Want to see Seresto shapes up against some of their biggest competitors? Check out our below guides:

    Frontline vs Nexgard.


    Seresto For Dogs | Why is Flea and Tick Treatment Important for my Dog?


    You may have heard of Lyme Disease or Rocky Mountain Spotted Fever. Depending on where you live, these tick-borne illnesses may even be common, particularly for people or dogs that spend significant amounts of time outdoors.

    However, there are actually many tick borne diseases throughout the country, a full list of which you can find here.

    It is untrue that there are areas in the United States that do not have ticks.

    This distribution map published by the Centers for Disease Control and Prevention, shows that every state does have at least one species of tick.

    However, some more specific environments, such as urban spaces, likely have less chance of encounters with ticks than thick woodsy environments where ticks are more common.


    Fleas are also vectors for a few nasty conditions that can affect your dog. Many canines are sensitive to their bite, causing scratching at the site of the bite and in some cases excessive licking and biting which can lead to “Hot Spots.”

    These are patches where your dog has licked away the fur. They are painful for your dog and can also be persistent and difficult to treat.

    Fleas can also carry tapeworms, a nasty parasitethat can also spread to humans.

    Although rare, fleas can also pass on “Cat Scratch Disease,” Bartonella, and Maurine Typhus, very serious diseases that pose a threat to human health.

    Fleas also pose the potential threat of infesting your home.

    Once established in carpets, furniture and bedding, fleas can be extremely difficult to irradiate, sometimes requiring professional extermination.

    By properly treating your dog, you can prevent the primary means that fleas will enter your house, stopping them before they have a chance to take root.

    Safety Precautions When Using Flea and Tick Dog Collars

    • Never combine flea and tick treatments since this can cause an overdose of medication
    • Never use products designed for cats on dogs, or vice versa
    • Always carefully follow the manufacturer’s instructions for use
    • Keep children from touching or playing with medicated collars
    • Wash your hands after fitting or touching the collar
    • Stop use immediately and call a vet if your dog shows any concerning symptoms

    Are Seresto Collars Safe?

    When we started our research for Seresto Collars, we did find reports from customers with safety concerns about this product. It is important to note that ALL products that use pesticides to kill fleas and ticks have similar customer complaints associated with them.

    Anecdotal reports are hard to verify, may be related to something other than the product, and are not the same as scientific research on the safety of a product.

    Note that for example, a very popular product, such as Seresto Collars, is going to be used by millions of dog owners.

    Even if a tiny fraction of these owners have a problem, it is likely to show up on the internet.

    Since it is impossible to assess the frequency of problems from such anecdotal reports, it is also impossible to call a product unsafe strictly on those accounts.

    Still, we saw enough reports that we wanted to give our readers some resources to learn about potential problems with this product, so that you can talk to your vet and decide if this is the right product for flea and tick control.

    If you decide it is, we have linked the two collars now available on the market so you can be sure to get it in the right size. Click HERE to jump to that review.

    If you decide you want to try some other products to see if they provide flea and tick protection without the risk of pesticide-based formulas, click HERE to learn about some alternative products that may be what you are looking for.

    Veterinarian Perspectives

    In some cases, veterinarians have raised concerns about the safety of Seresto flea and tick collars, others have deemed the product safe.

    Here are a few references to read if you are interested in the advice of some professional veterinarians:

    National Pesticide Information Center

    A helpful resource for dog owners, provided by a partnership between the EPA and Oregon State University is the National Pesticide Information Center.

    This organization sponsors an information phone hotline for consumers to call and get the most up-to-date information on pesticides of all kinds, including topical flea and tick treatments used for domestic pets.

    The helpline is available Monday – Friday, 8:00 AM – 12:00 PM, Pacific Time. The number is 1-800-858-7378.

    Environmental Protection Agency (EPA)

    The EPA released this report in 2016. Their conclusion is that Seresto collars are safe for pets wearing these flea and tick collars.

    They do, however, recommend that children should not play with the collars, and should be quarantined from the pet during the first day that they are wearing the collar to minimize exposure to the child.

    This report also mentions that the EPA has received reports of adverse effects in pets and promises further evaluation.

    Interestingly, the EPA did evaluate another pesticide in 2014 that was used in flea and tick collars called, propoxur. They noted that there were unacceptable risks to children in the first day of application.

    Sergeant's and Wellmark were the two companies that were selling these collars, and they subsequently voluntarily pulled them from the market.  

    U.S. Food and Drug Administration

    Although the regulation of topical flea and tick products is the jurisdiction of the EPA, there is also some general oversight provided by the FDA for these types of medications. You can find the Seresto registrations with the FDA here and here.

    In addition, some helpful information on the use of external flea and tick products can be found here

    Included in this document are important helpline numbers for reporting incidents of negative reactions from the use of these products.

    Seresto Dog Collar Customer Reviews 

    Seresto dog collar customer reviews on Amazon show that this is the most popular flea and tick collar on the market.

    With nearly 10,000 customer reviews, the Seresto collar for large dogs gets a 3.9 star rating, with over 60% of customers giving it 5 stars.

    Among the near 20% of customers that gave it one star, about half reported that the collar was ineffective. Note that sometimes fleas and ticks develop regional resistance to pesticides, which may account for some of these complaints.

    The other half of the significant number of one-star reviews mentioned health problems and side effects from using this product.

    Although rashes, lethargy and loss of appetite were the most common symptoms noted by unhappy customers, a few of the reviews documented extreme adverse reactions, including seizures and neurological problems.

    At least 15 of the customer reviews sadly reported that their dog died shortly after use of this product.

    To contrast this data with the next most popular flea and tick dog collar, the Hartz Ultra Guard Plus, only 34% of customers gave this collar a 5 star rating.

    42% gave it a one-star rating. The reasons for negative reviews were overwhelmingly about ineffectiveness for flea and tick prevention.

    Among the 104 one-star reviews, six customers complained the product made their dog sick, and none reported death.

    Seresto Collar Side Effects

    Unfortunately, the product label for these flea and tick collars does not include potential side effects. Bayer has also failed to be transparent about potential side effects on their website.

    The instructional leaflet that comes with the product does mention “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 1 or 2 weeks without the need for collar removal.”

    The leaflet also warns to keep the collar out of the reach of children, and to not let them play with the collar.

    However, we can learn more by looking at the active ingredients, flumethrin and Imidacloprid.

    Symptoms of toxicity with Flumethrin:

    • Ataxia (loss of muscle coordination)
    • Hyperreactivity (behavioral changes)
    • Tremors
    • Skin tingling
    • Extreme lethargy
    • Drooling
    • Vomiting
    • Diarrhea
    • Incontinence

    Symptoms of toxicity with Imidacloprid:

    • Rash
    • Fatigue
    • Twitching
    • Cramps
    • Muscle weakness
    • Difficulty breathing

    Both of the active ingredients have raised environmental concerns about their impact on bees, birds and aquatic life.

    If your dog starts showing any of these symptoms after using a Seresto collar or any other product containing pesticides, immediately take it off and wash your dog with a mild detergent and plenty of water.

    Call your vet to talk and make an appointment so they can do a proper evaluation and diagnosis as well as recommend alternative treatments if necessary.


    My Dog Ate a Seresto Collar!

    If you suspect your dog has eaten all or part of a Seresto or any other medicated flea and tick collar, take them to the veterinarian right away.

    If your vet is unavailable due to a holiday, call the APSCA Poison Control Center Hotline at (888) 426-4435.

    All Flea and Tick Pesticides Can Trigger Potentially Severe Symptoms

    Some veterinarians have pointed out that there are potential adverse side effects with all pesticide-based medications used for flea and tick prevention including collars, drops, pills, shampoos and sprays.

    For example, Dr. Deva Khalsa points out that the active ingredients in several flea and tick treatments have been implicated in a variety of health problems, including thyroid cancer, kidney toxicity, nervous system issues, extreme lethargy and seizures.

    It is critical to work with your vet to find the right product for you and your dog.

    Since flea and tick-borne illness are also potentially deadly to your dog, you will need to weigh the risks and benefits with your veterinarian.


    Do Seresto Collars Work?

    With the exception of some regions where fleas and ticks may be resistant to the active ingredients, there is plenty of evidence to suggest Seresto collars provide an effective treatment for these external parasites.

    Your veterinarian can confirm if the product is working well in your area.

    • When compared to other flea and tick collars by average customer reviews, Seresto collars seem to be significantly more effective than other dog collars on the market that we reviewed.
    • As we indicated above in our summary of customer reviews, the vast majority of customers of this extremely popular flea and tick collar for dogs rated Seresto collars as effective to very effective.
    • Independent research studies have also confirmed that Seresto collars provide effective treatment for fleas and ticks. See(Stanneck et al., 2012) and (Brianti et al., 2013) for more information.

    Seresto Collar Reviews

    Benefits of Seresto Dog Collars

    Despite some concerns noted above about the safety of this product, the fact is that thousands of pet owners have used this collar with no ill effects. In fact, many pet parents have found it to be very effective in the treatment of fleas and ticks.

    Here are some other benefits of using this collar over other flea and tick products:

    • Single application will yield 5-8 months of protection
    • Customer reviews consistently mention it is very effective
    • Low odor after the first few days
    • Non-greasy
    • Kills fleas and ticks on contact, without the need to bite your dog to be effective
    • Water resistant, safe for bathing and swimming
    • Also kills lice and can be effective in the treatment of sarcoptic mange

    If you decide that the possible risks of Seresto collars are outweighed by it’s effectiveness in preventing the dangers presented by fleas and ticks in your region, you can buy this product in two sizes:

    • For dogs weighing up to 18 pounds
    • For dogs weighing over 18 pounds

    Flea and Tick Collar Alternatives to Seresto

    Hartz Ultraguard Plus Flea &Tick Dog Collar

    As we mentioned above, there are adverse side effects that are possible for all pesticide-based dog collars. Pesticides are, after all, poison.

    However, if you have decided that Seresto is not the product you feel comfortable using, but still want the protection of a medicated dog collar, this is an alternative.

    Active Ingredients:

    • Tetrachlorvinphos – 14.55%
    • (S) Methoprene – 1.02%
    • Up to 7 months of protection
    • Kills fleas and ticks
    • Prevents flea eggs from hatching, interrupting the life cycle
    • Water resistant
    • For use in dogs of any size, 12 weeks and older
    • Cuts for adjustable fit to any size dog up to 26”
    • Can take several weeks to stop an infestation
    • Several customers reported this product as ineffective
    • Only has a 3-star overall rating on Amazon

    All-Natural Flea and Tick Products





    Vet’s Best Natural Flea and Tick Spray

    • Eco-friendly
    • Nice smelling product
    • Safe for puppies, 12 weeks and older

    Wondercide Flea and Tick and Mosquito Control Spray for Cats, Dogs and Home

    • Kills and repels fleas, ticks and mosquitos
    • Delicious scent
    • Grease free formula

    Natural Chemistry Flea and Tick Shampoo

    • Pesticide free – safe for use around children
    • Also effective with black flies and mosquitos
    • Eco friendly formula

    After thoroughly reviewing as many products as we could find, Wiley Pup did not identify any all-natural flea and tick collars that seemed to work well enough to recommend to our readers.

    However, we did find several all-natural flea and tick preventatives for dogs that do have a good track record.

    Vet’s Best Natural Flea and Tick Spray

    Active Ingredients:

    • Peppermint Oil – 0.30%
    • Eugenol (Clove Oil Extract) – 0.70%
    • Sodium Lauryl Sulfate – 2.70%
    • Kills and repels fleas and ticks as well as flea eggs
    • Spray directly on your dog or on bedding, furniture or carpets
    • Safe for puppies, 12 weeks and older
    • Eco-friendly
    • Safe for use around children
    • Nice smelling product
    • Made in the USA
    • Pesticide free
    • Extremely popular – almost 5,000 reviews with 66% percent giving 4 stars or better
    • Can cause mild to moderate eye irritation if it gets into you or your dog’s eyes
    • About 15% of customers gave this a one-star rating, noting mostly ineffectiveness or problems with their cats being bothered by the smell
    • If you have a cat in your household, this may not be your best option since both peppermint and clove oil can prompt adverse respiratory and dermal reactions in cats

    Wondercide Flea and Tick and Mosquito Control Spray for Cats, Dogs and Home

    If you have cats in your home, this natural flea and tick repellent is a safe alternative to Seresto collars that will not bother your feline pets. In fact, this can be used on both cats and dogs safely.

    It both kills and repels so you can rely on this product to quickly reduce an infestation in your home. This responsibly sourced and eco-friendly product gets high reviews for effectiveness and one of the most popular products in it’s class

    A little expensive, and requiring frequent reapplication to stay effective, you may want to look at other options if finding a budget friendly option is your top priority.

    Active Ingredients:

    • Cedar Oil – 4.2%
    • Sodium Lauryl Sulfate – 2.2%
    • Lemongrass Oil – 1.5%
    • Sesame Oil – 0.1%

    In addition to the spray, Wondercide also makes insect control spray for the garden, ear wash, shampoo bars, as well as a special detox bentonite clay for the truly pampered pet.

    • Kills and repels fleas, ticks and mosquitos
    • Clove and Peppermint oil free, making it also safe for use around cats
    • Delicious scent
    • Grease free formula
    • Use directly on your pet as well as surfaces in your home
    • Safe around children
    • Eco-friendly
    • Family owned business
    • Human grade ingredients for the highest quality
    • Product is both made and sourced in the USA
    • 68% of customers give this product a 4 star or better rating, citing mostly effectiveness and pleasant smell
    • Pricier than some other’s in its class
    • You will have to reapply fairly often
    • About 15% of customers gave this a one star rating, mostly citing ineffectiveness or the strong smell of the product

    Natural Chemistry Flea and Tick Shampoo

    For some people, a flea and tick shampoo is a better fit than a spray. If you find yourself bathing your dog weekly, you may be better served with a shampoo product.

    This all-natural shampoo receives high marks for effectiveness among most of the customers that reviewed it, along with praises for the lovely smell of cinnamon. In addition, this is a budget friendly solution for flea and tick control.

    Natural Chemistry also makes other popular flea and tick control products, including Yard and Kennel Spraytopical drops, and an oatmeal shampoo formula for dogs with sensitive skin.

    Active Ingredients:

    • Sodium Lauryl Sulfate – 1.20%
    • Cinnamon oil – 0.50%
    • Cedar oil – 0.20%
    • Clove oil – 0.20%
    • Kills and repels fleas and ticks
    • Also effective with black flies and mosquitos
    • Pesticide free – safe for use around children
    • Eco friendly formula
    • Pleasant cinnamon smell
    • Inexpensive, particularly compared to other all-natural flea and tick products
    • 74% of customers rate this product 4 stars or above
    • Clove oil is known to irritate many cats, not a good choice for multiple pet households
    • Reapply after 7 days
    • May not be a great choice for white dogs, since
    • Does not lather as well as some other natural flea and tick dog shampoos
    • 8% of customers gave this product a one star rating, citing mostly unhappiness with the effectiveness against fleas
    • May not be a great choice for white dogs, since
    • May not be a great choice for white dogs, since


    At WileyPup, we want you to have the information that you need to make an informed decision about the products and gear that you choose for your dog.

    Given the importance of flea and tick prevention and treatment, it is critical that you have a conversation with your veterinarian before making a final decision on flea and tick medications.

    However, we wanted to make sure that you had the information you need to make the most of that conversation.

    This Seresto collar review has covered both the pros and cons of these popular flea and tick collars.

    While some consumers have had negative experiences with the product, the vast majority report a safe and effective experience with Seresto dog collars.

    Just in case you decide it is not the product for you and your dog, we wanted you to have some viable alternatives, including flea and tick collars that use other pesticide ingredients as well as some all natural flea and tick control alternatives that some of our readers may find most appropriate for their needs.


    How long does it take for Seresto to start working?

    The Seresto collar becomes fully effective after 24 hours. In 24 hours, it will kill existing fleas and become effective against new infestations. Seresto collars also prevent flea eggs from hatching.

    Is Seresto safe for humans to touch?

    There have not been many reports of Seresto collars causing adverse reactions in humans who touch them. At worst, it’s usually a light skin irritation. However, touching the collar too much is still not recommended, and you should wash your hands in cold water after doing so.

    Do you take the Seresto collar off for baths?

    It’s not necessary to take the Seresto collar off for baths. The collar is water-resistant, and it’s fine if you keep it on for a bath or when your dog goes for a swim. However, if you give your pooch baths very often (more often than once a month), you might want to consider taking the collar off. Frequent baths will not ruin the collar but will shorten the duration of effectiveness.

    Can a dog sleep in bed with a Seresto collar?

    It is safe to let your dog sleep in bed with a Seresto collar. However, direct contact between the collar and your skin and face should always be avoided.

    Sharon Elber (M.S. in Science & Technology) - Professional Dog Trainer

    Sharon is a professional dog trainer with over 10 years experience. She is also a professional writer that received her M.S. in Science & Technology Studies from Virginia Tech.

    For more info on Sharon click here

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