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Why You Need To Stop Using Flea Collars Today

Cedarcide blog post image, why you need to stop using flea collars today

Flea collars are one of the the most popular options for treating and preventing fleas in both dogs and cats. Typically, flea collars work by either transferring pesticides to your pet’s skin or by giving off a harmful gas that’s toxic to fleas. Unfortunately, the same features that make flea collars effective also make them dangerous to both pets and humans—serious, even life threatening, side-effects have been linked with exposure to the chemicals found in flea collars. The following is a list of reasons why it’s important you stop using flea collars on your pets as soon as possible.


A study conducted by the National Resources Defense Council (NRDC) concluded that flea collars, even when used as directed, can have “serious health consequences to humans.” The NRDC found that unsafe levels of pesticides from flea collars can remain on a dog or cat’s fur for weeks after initial use. These pesticide levels exceed acceptable EPA exposure limits, posing a serious risk to both adults and children when playing with pets wearing flea collars.

“It was also discovered that flea collar toxins are readily transferrable, moving easily from a pet to furniture, children’s toys, even directly to humans.”

One of the most common (and dangerous) chemicals found in flea collars is Tetrachlorvinphos (TCVP), an organophosphate insecticide that works by interrupting a flea’s central nervous system. Unfortunately TCVP—which the EPA lists as a carcinogen—also wreaks havoc on the human central nervous system. Which shouldn’t come as a surprise, given that organophosphates are a central ingredient in several biological weapons, including nerve gas.

Worst of all, children and pregnant women are especially at risk—learning disabilities, motor development, hyperactivity and behavioural issues have all been tied with exposure to flea collar pesticides. Public Health Scientist Miriam Rotkin Ellman—a key scientist in NRDC’s studies—has said,

“with a pesticide it doesn’t take very much to cause effects that will stay with kid[s] for the rest of their lives”


While residual toxins from flea collars can be hazardous to humans, they can be outright lethal for your pets. Ranging from skin irritation and gastrointestinal distress, to organ failure and even death, flea collars have a long history of harmful effects in both cats and dogs. When used as directed, flea collars are still known to cause severe chemical burns and seizures in pets. A quick look at product review sites like Consumer Affairs or outlets like Amazon is enough to get a sense of the suffering flea collars commonly inflict on pet owners.

In cases of ingestion or misuse (placing a dog-specific flea collar on a cat, for instance), flea collars are regularly fatal, with smaller and older pets being especially vulnerable. Flea collars are also notorious for interfering with pet medications—sometimes counteracting them, sometimes rendering them deadly. Even under ideal conditions, flea collars can be fatal to dogs and cats, as sensitivities to chemicals or allergies usually remain unknown in pets until it’s too late.


In contrast to received opinion, flea collars are not exactly highly effective. In most cases, flea collars can be useful at preventing flea infestations (if toxic treatments can be considered useful) but not at treating them. In fact, many flea collars are not even strong enough to kill adult fleas. Even when used properly, flea collars only serve to protect the area on or around your pet’s neck. Considering fleas tend to feed and hide primarily in pets’ armpits, groins, bellies and backsides, it’s not hard to see why flea collars are only so effective at controlling flea infestation.


At Cedarcide, we only advocate for family-safe, non-toxic flea & tick solutions. Thankfully, there are many pet-safe, family-safe options when managing and preventing flea infestation. Here are some of our favorites:

To protect your dog or cat from fleas, ticks, mosquitoes, mites and other harmful biting bugs, apply Cedarcide Original directly to their coat daily or before activities that expose them to fleas and ticks, such as dog park visits, walks, or hikes.

Cedarcide Original is also awesome for killing and repelling fleas, ticks, mosquitoes, mites and other unwanted bugs indoors, in all life stages, including eggs.


For a flea and tick-free yard, treat your entire outdoor space monthly, including shrubbery and bases of trees, with our family-safe Lawn & Garden Kit


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  1. My dog has used the Saresta collar for 3 years. This year after putting a new one on her in the spring, she began to eat off and on, throw up a few times and then by mid-summer I discovered a soft large cyst on her neck. The doctor said it seemed like it was more in her skin and not attached. She has been lethargic and lacks an appetite. Then she developed another large cyst on her hip that she bites at constantly. I finally concluded that it must be the collar. I took it off yesterday and continue to monitor her. I don’t think I like the toxic chemicals that are going into her body, so am looking for a good way to detox her naturally.

  2. Adeline Delores Lyles

    Hi, I started using Seresto, and my puppy started scratching really bad. Neck area, as well as neck area I took the collar off just to see is any more scratching none, only had on her for about 2 weeks so glad I read all the issues with this flea collar, not sure what to use now. If any one can suggest a good medication for fleas please let me no. She has no fleas and I do not want her to get them.

    1. Jonathan At Cedarcide

      Hi Adeline!

      Many of our customers and our employees use Cedarcide Original daily or every other day instead of traditional, toxic approaches like collars. Food for thought 🙂

  3. Lisa Nicolosi

    I bought a Seresto collar for Dog and put it on. I had a male cat I loved who was extremely close to my Dog . They slept together played outside together. About a week after putting the collar on my dog . My Cat started to act funny. A few days later the cat could not walk. I took him to the Vet they drew labs and said they were normal. He stayed their a few days getting fluids but never recovered. A did not know medication of a dogs flea collar could be toxic to my cat. I’m devastated and have to live with the quilt I feel for using the collar.

  4. I am wondering has anyone had any issues with Seresto collars on thyroid issues. It is our first time using a flea collar and the most expensive as I heard they work the best and they did do the job, but wondering as health issues have become in my dog since using Seresto. We noticed at first both thyroids were enlarged just a little and now they have really got big over the last few months as we removed the flea collar early this year. At this time we are waiting for the biopsy to be schedule the doctor says he is sure it is cancer. I have had many lab dogs and in my family and never heard this is common as the doctor is saying as we usually end up dealing with hip issues with our lab dogs. If it is cancer then our dogs lifespan is less than 2 years. I am just hoping it is something of a reaction from wearing this collar and it can be cured. Any thoughts or recommendation would be helpful as what I am hearing possibility from the doctor is hard for me to accept.

    1. Not a dog but we had thyroid problems in our cat diagnosed when she was 7 which is highly unusual in a cat of her age. Caused seizures and kidney problems. She had radiation treatment and is now clear. She had prior to this always worn the seresto collar but never again as I am sure this was the cause

    2. Yes, not on our dog but our cat, enlarged thyroid heart issues and one kidney has failed. Have had to have radiation treatment. Will never put a seresto collar on any pets ever again

  5. Seresto collar has poisoned my dog & I am so regretful that I didn’t do better research. I was told it was a more natural alternative.. WRONG. Took my sweet pup to the vet after serious issues & just praying she pulls through.

  6. We just got a puppy who has severe skin irritation (burns) due to having worn a serresto flea collar. What can I apply to her skin to alleviate the itching? I have already given her an oatmeal bath.

    1. Jonathan At Cedarcide

      Hi, Laurie

      We’re so sorry to hear about your poor pup. We can’t make any recommendations for that at this time, but we do strongly suggest visiting a vet to have her checked out ASAP.

      Best of luck!

      1. I was about to put collars on both of my girls just now, but I stumbled onto this page, and thank GOD I did!!! After reading these stories…
        No way am I using flea collars! Both of my dogs have fleas, but I’m gna try these other options listed, thankyou all!!!

        1. Jonathan At Cedarcide

          We’re so glad to be of help, Bonnie! 🙂

    2. Shirley Luoma

      I put a seresto collar on my 16 month old white GSD. He was diagnosed with Lymes just prior to the collar. Was on antibiotics for a month. He began scratching something fierce and because of all issues was not sure what was going on. He would have red raised areas and he was miserable. Finally considered allergy to the collar. Removed it 2 days ago and the rashes and itching are subsiding, at least have lessened so am assuming that the collar did this..? Allergy to Seresto collars..??

      1. Jonathan At Cedarcide

        From what we understand, this is a fairly common reaction to these collars, they’re scary, scary things that can really harm our pups. A simple search of the reviews on Amazon alone shows tons of harmful, even fatal reactions to these collars.

    DEAR Bayer : Makers of Seresto flea & tick collar
    I am writing this letter telling you at Bayer my experience with your Seresto collars. I bought 4 collars for my 4 dogs on 5/6/19 at the Abington animal hospital in Abington Ma. I have a female 13 1/2 yr old Cocker spaniel, a male 2 yr old Golden doodle, & 2 male Cavachons 10 1/2 & yrs old. On Thursday 6/6/19 @ 3am my 5 yr old Cavachon Dominic had a seizure, we immediately took the collar off him along with the Danny our other Cavachon & had our son at home take the collars off our other 2 dogs. Dominic vomited pooped & had muscle weakness during the night. he seemed to bounce back some the next day. Later that same day 6/6/19 at 4:15 pm my 10 1/2 yr old Cavachon Danny had a seizure. We took him to the Country Veterinary clinic in carver ma near my seasonal camper in carver. There he was examined They did blood work & checked him out & couldn’t find & issue other than hi sugar & phospherous levels. They said try feeding both dogs boiled chicken & rice or boiled hamburgh & rice or pasta. later that night Dominic had another episode where he fell over & vomited & pooped all over our campers deck. He was lethargic all day on Friday 6/7/19, He would not eat anything. The 10 1/2 yr old Danny was lethargic early in the day he perked up in the mid afternoon & ate chicken & pasta while Dominic remained lethargic.
    On the morning of Saturday 6/8/19 my 10 1/2 yr old Danny had another seizure with coughing. He was laying down in our camper kitchen floor as we patted him to bring him out of it. Suddenly his legs started to stiffen & started wrenching back & forth towards each other as he died at my feet. We brought Danny’s body back to the vet at the Country Vet clinic that morning when they opened. The Dr took him in the back room to do an autopsy after they closed at noon. We came back at 11am with Dominic who remained lethargic & still was not eating. he did blood work & iv fluids to hydrate him. Dominic’s blood work showed hi phospherous levels like Danny’s but his blood sugar was normal compared to Danny.he thought Dannys hi sugar was caused by the seizure. Dr Simpson’s autopsy did not show any abnormalities of any of Danny’s organs kidneys liver, lungs, stomach. He had some thickening of the arteris around his heart which may have caused the cough he had along with the hi pollen this spring. Dr Simpson still could not find a reason for all that had happened to our cavachons & the seizures that they had 15 hours apart from each other.
    My dogs are always with us they got into nothing that might cause these problems what so ever. We looked up the ingredients of the Seresto collars especially the HIGHLY TOXIC pesticides used by the name IMIDACLOPRID & FLUMETHRIN. We found that every symptom both our little dogs had can be caused by this pesticide that you use in these collars. the only thing we did different with our dogs is to get them these Seresto collars. Now my Danny is dead & as i write this on 6/17/19. My Dominic has showed some improvement but is still far from the active & playful dog he was before his seizure on 6/6/19. We took Dominic back to the vet on Monday 6/10/19 where he received more iv fluids & shots of prednisone & an anti neahsea to help his appetite out. he also gave us pills of both meds to give him for 5 days. The vet gave Dominic as he went 5 days without eating but just drinking some special dog food. On Wednesday 6/13/19 Dominic finally ate some without us feeding him. His back legs were still weak where we had to carry him down to go the bathroom. On Thursday 6/13/19 he finally went down then back up the stairs on his own, the same on Friday 6/14/19. By the end of friday & after a few short walks his back legs were still weak trying to stand. He finally moved his bowels on Friday 6/14/19 2 times. On Saturday 6/15/19 his birthday at around 5:10 pm he kind of rolled over & couldn’t get up. My wife picked him up but he seems just dead tired. He has been eating a little better each day but has continued to vomit on occassion. Dominic is at best 1/2 of what he was before hi 1st seizure on 6/6/19 @ 3AM. i’m just hoping there’s no neurologogical damage IMIDACLOPRID can cause. The vet told us he could not rule out the collars from causing these symptoms in our beloved pets Danny & Dominic. My regular vet of the Abington animal hospital where we bought the collars. He basicly said it’s like hitting the lottery it’s possible the collars may have caused it. both vets said what are the odds of 2 dogs 1 month after putting these collars on them having seizures 15 hours apart from each other.
    My wife & i truly believe your collar killed my prescious dog Danny& has almost caused Dominic to die twice on 6/8/19 & 6/9/19. We have spent $285 for the 4 collars we bought our dogs that wore them for 1 month to the day 5/6/19 – 6/6/19. It killed 1 dog & another is still fighting the effects of them as i write this letter on 6/17/19. Then throw in my vet bills treating 2 dogs & getting another 1 checked out its over $1,500. I will tell you this now i will tell every pet owner i know in person & others on social media what i truly believe what your Seresto flea & tick collar did to our beloved family pets.I’m also sending with this letter my $15 rebate for each of the collars i purchased for my 4 dogs. Wow isn’t that nice, a big $60 back for my poor dead Danny & possibly another dog dying down the road or never being his playful energenic self again.
    Thank you for a horrible 2 weeks. This is the letter i sent to Bayer earlier last week along with my rebate mail in for the collars. I cant wait to hear from them if they even do.
    As of yesterday 6/29/19 Dominic passed away after not eating for the last 5 days on his own . My wife & i were actually force feeding him by spoon he was throwing it up meds & food then the water. He got an anti nausea shot on 6/27/19 by the vet along with pills for the same. He just got worse & worse till he passed. Now he’s back with Danny in doggie heaven as he’s also been grief stricken from Danny’s passing 3 weeks ago to the day. Dom Dom as we called him was the black & white dog. these were my best dogs ever Danny got me thru 10 surgeries over a 9 year period with Dom Dom also there for a few. these cavachons are the most loving & happy dogs i have ever had & now they’re gone over a chemical collar that can kill your dog by the pesticides in them. I truly believe it killed them both & feel the need to warn all you pet owners. Right now my beloved dom dom is in my fridge because the other hospital i brought him too after he passed didnt have a fridge only freezers. I am going to bring him to the treating vet tomorrow monday july 1st so he can autopsy Dominic if he has been in a freezer they can’t do it.
    The vet called me with what he found on Doms autopsy on 7/1/19. He said all Doms organs showed no problems whatsoever. Even his stomach throughout all his vomiting the last 3 weeks & his loss of appetite which was a complete loss the last 6 days. When we brought Dom to him on Thursday 6/27/19 he gave him an anti nausea shot & some pills for that & see if he would try eating. If that didn’t work he said you may have to go to a animal hospital & maybe have a scope to see what his stomach problem is. So when I asked would a scope have done or found anything he said no his stomach was fine. He said he took specimen samples from liver & other organs to be sent out to a lab. He also talked to Bayer the maker of the Seresto collars. They say the collars don’t do this but they will pick up the cost of the lab work. Isn’t that so nice of them their product killed my beloved dogs. God forbid this get out & slow down their profits on the collars that can kill pets across the country. It’s all about profit over pet health. The vet again told me he can’t rule out the collars he just doesn’t understand how a healthy 5 year old like Dominic died when he shouldn’t be dead now. I’ve looked online & found many hundreds of pets & their owners going thru the exact thing we went thru. Some dogs survived others didn’t. I makes me sick to think this is allowed by a company like Bayer but then I also found out they bought Monsnato . Monsanto has been killing people for over 100 years with their cancer causing products so what is the problem if they are killing pets now.

    1. Stacy A. Martin

      Did you hear back from them?! We had to put down our 6 year old boxer last summer and I swear it was because of the Seresto collar!

    2. elizabeth kamer

      i just read yur letter about the seresto flea collar.i had to put down my beloved dog july q0th. the et didnt even ask me or my husband if we wuld like fr to put it on our dg never wore a colar of any kind. the vet just came and said she needs this and that fast he had it on her.without our permission.and i told him he put it on to tight. and he said kno the tighter it is the better it works.i was ike what.? and then the technisian she had a pill in her hand and she stuck in my dogs but with asking us .the vet said it was on the house. said it was for fleas. anyway .but they the vet just came right in the room that fast .and gave my dog a shot of something.again not even teling us what it was.charged us 59;00 dollars for the collar.but my dog couldnt walk or eat. she drank a little water. she waoul just set looking at the wall with her head bobbing up and down.from left to right trying to catch her breath.she went from 17 pounds to12 pounds.i told my husband to take it off the next day. but it was to late for her.she was 15yrs old she didnt have a chance.being as old as she was.she was starting to really go down me and my husband had to make that descion to put her down .we took her to my moms vet.we adk him if there was anything we could do for her.he said know yu guys are doing the right thing fr her.well it sure dont feel like i was so hard. no she over in her chair in my room with her favorite blanketin her urn with her name on the front with it saying babygirl in gold plated.with her teddy bear.that she so sorry about your dogs.i cry for mine everyday.she was all ways with me every second every minute of the day .i miss her so
      was a lea pill.

    3. I don’t have time to really respond ,I have Togo to work now. Our dog also died I think from the collar. I would like more info . We spent 4,000 dollars on our dog to get her well and never really got a true reason why she got sick emediatly and in 3 weeks was dead.

  8. Put Seresto collar on dog last night n woke up with her coughing n throwing up phlegm. HELP.SERESTO CAME HIGHLY RECOMMEND.
    MY 9lb HAVANESE is obviously reacting Her eyes also got red last nite around whole eyes

    1. Jonathan At Cedarcide

      Hi, Greychen!

      Unfortunately, these types of reactions (and worse) are not uncommon with chemical-based flea & tick prevention products. We suggest consulting a vet ASAP, and considering more natural options for the future. Let us know if we can be of any more help.

    2. Michelle Linn

      Omg!! I was just about to order 5 of ther collars for my dogs but thought I’d look at reviews. Actually I was looking at ther discounted priced ones from the Sharkchili company. Says they are all natural and names the herbs like cloves etc… all safe. They look like the Seresto collar though. I think I’ll stick with the other method I haven’t had issues with although it’s still chemicals and putting in my dog’s through their skin which is what I was trying to get away from. My dogs don’t wear collars either anyway…. Thank you for this. I won’t spend the $100. I can’t take that chance. I so sorry this happened to you.

  9. yolanda brancato

    instead of using toxic insecticides . bathe your pets with Dawn dish soap and watch the the fleas fall off dead..I volunteer at the county shelter and that is what we use.

    1. Jonathan At Cedarcide

      Toxic chemicals are the worse! Thanks for sharing Yolanda! But did you know Dawn actually contains chemicals, too? Chemicals the Environmental Working Group considers both toxic and groundwater pollutants? Surprising, right!?

  10. Pat – try coconut oil for the itchy spots!

  11. shirley miller

    You have someone (Pat) ask you about Seresto but I hope you might have some info for me. I have used Seresto for three years recommended by my Vet. It did work very well in killing ticks and fleas within two days. The one problem I am concerned about is Robbie had three small black spots with very pink skin under them and he scratched constantly there. He did not scratch anywhere else after apply the collar. I asked the Vet if he was reacting to the collar around his neck but she said no. So I kept on using them until this year and the spots got more irritated so I took the collar off but he still scratches his neck where the collar had been and the spots look worse. It’s getting to be tick time and I have no protection for him at all. I don’t know how to treat the irritation. I have bought your spray and one other liquid but I have not bought the flea/tick brush yet. He is afraid of the spray. Would this be safe for him?

    1. Jonathan At Cedarcide

      Hi, Shirley.

      We’re very sorry to hear about your pup’s irritation, that can’t be comfortable. Unfortunately, Seresto has been linked with multiple health complications, including skin irritation, which is another reason we only feel comfortable suggesting non-toxic solutions to our customers. Because we’re not vets, we don’t feel confident making suggestions about the health issue your pup is currently facing, although finding a way to keep him from scratching (have you tried a cone?) is one idea. Cedarcide Original can certainly help with the flea & tick protection. However, we would recommend avoiding spraying any of the sores or any other open skin directly. The brush would be an option for applying if he’s afraid of the spray, but also simply spraying your hands and applying to him that way works also.

  12. Do u have any information on Soresto collars? Thank you, pat

    1. Jonathan At Cedarcide

      Hi, Pat!

      We do not have any info on those collars specifically, but we have heard some pet parents share negative experiences with their toxicity. As a rule, we only suggest natural alternatives to our customers because of the many horrible stories we’ve heard regarding toxic flea & tick products. Thanks for the comment!

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