Seresto Cat Collar Review: Read the Cat Stamp (2026)
A seresto cat collar review starts with the EPA cat stamp. The 8-month wear line, the 10-week age line, and the incident record stay on the pages that printed them.
In this review 8 sections
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Read the cat stamp, then the fit
A seresto cat collar review on this page is the EPA Seresto Cat stamp, Reg. No. 11556-191, dated 07/13/2023, plus Elanco’s current US cat page. The stamp lists imidacloprid 10.0% and flumethrin 4.5%. Directions are one collar, cats and kittens 10 weeks and older, continuous wear, and replacement after 8 months. Existing fleas are killed 24 hours after the collar goes on. After that, new fleas are killed within 2 hours. Ticks already on the cat come off at fitting. Prevention of new tick infestations starts at 48 hours, and new ticks are addressed as quickly as 6 hours after that window. The score 3.5 is an editorial label fit: the duration and the pest lines are specific, and the post-approval list plus EPA’s mechanical-trauma finding are part of the same decision to leave the collar on the market.
Collars already on this page
- EPA Reg. No. 11556-191
- 10.0% and 4.5% on this stamp
- Replace after 8 months
- Same Seresto Cat family
- Still one collar per cat
- A spare for the 8-month swap
- A different shopping collar
- Not this registration
- Read that carton on its own
- A different aisle collar
- Do not paste Seresto percentages
- No Hartz month count printed here
How we evaluated
This evaluation uses published product labels, guaranteed analyses, and recall records.
The score is an editorial label fit for a seresto cat collar review. This page uses the EPA Seresto Cat file dated 07/13/2023, EPA’s July 13, 2023 mitigation notice, EPA’s Seresto pet collar review, and Elanco’s current US cat page. A number stays on the document that printed it. The other two collars stay on their own cards.
Editorial evaluation from published labels / literature — not a lab test or boarding trial.
Editorial picks are not sold to brands. How we make money.
What the cat stamp actually says
Seresto for cats is a pesticide collar, regulated by EPA, not an FDA drug. The file reviewed here is the cat registration, 11556-191, not a dog collar and not a non-US leaflet. Gram weights and 7-to-8-month lines from other countries stay off this page. The US directions are 8 months, continuous wear, and replacement at the end of that period.
| Item | What that file prints |
|---|---|
| Actives | Imidacloprid 10.0% and flumethrin 4.5% |
| Registration | 11556-191, dated 07/13/2023, expires 07/13/2028 unless extended |
| Age and dose | Cats and kittens 10 weeks and older, one collar |
| Wear | Continuous. Replace after 8 months. |
| Fleas | Existing fleas at 24 hours. Then new fleas within 2 hours. |
| Ticks | Remove ticks already attached. New-tick prevention starts at 48 hours. New ticks as quickly as 6 hours after that. |
| Fit | About two fingers. No leash. Cats only. |
Which number stays on which collar
| Card | Use this | Leave this off |
|---|---|---|
| Seresto 1 count | 11556-191, 10.0% and 4.5%, 10 weeks, 8 months | A non-US gram weight or a 7-to-8-month leaflet line |
| Seresto 2 count | Same family, still one collar per cat | A second strength, or two collars on one neck |
| PetArmor Extend | Its own carton, unread as an EPA stamp here | Seresto’s registration and percentages |
| Hartz UltraGuard | A different collar already linked | Seresto’s age line and month count |
Seresto Cat collar, 1 count
Best for: One cat, 10 weeks or older, that will keep the collar on and have the fit checked
- Registration
- EPA Reg. No. 11556-191. Stamp dated 07/13/2023. Time-limited; expires 07/13/2028 unless extended.
- Actives
- Imidacloprid 10.0% and flumethrin 4.5%, in a polymer matrix.
- Who
- Cats and kittens 10 weeks and older. One collar. External use on cats only.
- Wear
- Continuous for the 8-month protection period. Replace after 8 months.
- Fleas
- Existing fleas killed 24 hours after application. Then new fleas within 2 hours, for 8 months.
Seresto Cat is an Elanco US Inc. pesticide collar. The accepted stamp reviewed here is EPA Reg. No. 11556-191, dated 07/13/2023. Active ingredients are flumethrin 4.5% and imidacloprid 10.0%. The decision notice in that same file makes the registration time-limited. It expires 07/13/2028 unless Elanco requests an extension and EPA agrees. That date is a review leash. It is not a cancellation.
Directions say one collar per cat, fastened around the neck, for cats and kittens 10 weeks of age and older. Do not use it on other animals. Do not get it in the eyes or mouth. The collar is worn continuously for the 8-month protection period. Check the fit as kittens grow. Replace it after 8 months. If the collar is lost, a new one may go on immediately. Do not attach a leash. The stamp says a leash may cause breakage.
Product information: the collar kills existing fleas on cats 24 hours after initial application. After 24 hours, any new fleas are killed within 2 hours, with protection against further flea infestation lasting 8 months. It also says the collar kills fleas which may cause flea allergy dermatitis or flea bite hypersensitivity. That is a flea-kill line. It is not a promise that the skin disease is gone. Pre-existing pupae in the home may keep emerging for 6 weeks or longer. The stamp says to treat the cat’s living area with a product approved for home use.
Ticks already on the cat before treatment may not be killed immediately and may stay attached and visible. At application, remove ticks already on the cat. Prevention of infestations with new ticks starts at 48 hours. Any new ticks are repelled and/or killed as quickly as 6 hours after that initial 48 hours. The accepted file also contains optional marketing lines, including one that says treatment kills existing ticks at 48 hours of initial application. That optional line does not erase the instruction to remove ticks at fitting. Optional claims on the same file name flea larvae and four ticks: deer (black-legged), American dog, brown dog, and lone star. Elanco’s current US cat page lists that same spectrum and the same 10% and 4.5% pair.
Fit about two fingers between the collar and the neck. Pull the excess through the loops and cut it to no greater than 1 inch beyond the loops, unless the cat is a growing kitten and needs extra length. A release mechanism is designed so a trapped cat can usually widen the collar. Reflector clips, if used, close permanently and are a choking hazard for children. Wash hands with soap and cold water after fitting. People sensitive to the ingredients should avoid contact. Keep the collar in the bag until use.
Pros
- The age, wear, and flea timing are printed on the directions, not on a shopping title
- A release mechanism is part of the how-to-apply text
Cons
- The post-approval list is long, and the collar comes off if those signs show up
- This is flea and tick control, not a heartworm or intestinal-parasite product
Seresto Cat collar, 2 count
Best for: A second eligible cat, or a replacement dated 8 months out
- What it is
- The same Seresto Cat family as the single collar.
- Dose
- Still one collar on one cat. Still 10 weeks and older.
- Wear
- Each collar is still a continuous 8-month wear, then replacement.
- Leave off
- A second set of active percentages. This carton does not get its own invented strength.
- Leave off
- Permission to stack two collars on one neck.
The 2-count carton is the same Seresto Cat family as the single collar. It is useful for a second cat that is 10 weeks or older, or for holding the replacement you will fit after 8 months. It is still one collar per cat. It does not change the registration, the 10.0% and 4.5% line, the fit, or the instruction to wear the collar continuously. Elanco’s US page says the EPA does not require an expiration date on Seresto Cat packaging, and that the collar should stay in the original packaging until use. Do not open the spare pouch early.
Pros
- A dated spare matches the replace-after-8-months line
- A two-cat house can keep each cat on one collar
Cons
- Two collars do not halve the age rule or the adverse-event list
- An unused collar stays in the closed pouch until the day it goes on
PetArmor Extend collar for cats
Best for: A shopper who will compare registration numbers instead of treating two collars as clones
- On this page
- A separate product already linked from the old article. No new product was added.
- Not transferred
- Reg. No. 11556-191, imidacloprid 10.0%, and flumethrin 4.5% stay on Seresto Cat.
- Not transferred
- The 10-week line and the 8-month replacement sentence stay on the Seresto stamp.
- What to compare
- Registration number, active percentages, age line, and adverse-event text on that carton.
- What this page did not open
- A PetArmor EPA stamp. No PetArmor percentage is printed here.
PetArmor Extend for cats is the other long-wear collar already linked on this page. A shopping title that says the actives match Seresto is a shopping clue. It is not EPA Reg. No. 11556-191. Imidacloprid 10.0% and flumethrin 4.5% stay on the Seresto Cat stamp until the PetArmor carton in your hand prints its own registration, percentages, age line, and adverse-event text. This page did not open that stamp, so it does not borrow Seresto’s 10-week line or Seresto’s 8-month replacement sentence either.
Pros
- It stays visible so the Seresto card is not the only collar in the search
- Refusing to clone the stamp is the useful comparison
Cons
- A shopping title that says the actives match is not an EPA stamp
- This page will not invent a PetArmor age gate or month count
Hartz UltraGuard collar for cats
Best for: A shopper comparing a different collar without moving Seresto's numbers onto it
- On this page
- A separate collar already linked. No new product was added.
- Not transferred
- Seresto's 10.0% imidacloprid and 4.5% flumethrin.
- Not transferred
- Seresto's 10-week age line and 8-month replacement sentence.
- Not printed here
- A Hartz month count or a Hartz age gate. Those were not opened on an EPA stamp for this rebuild.
- Fit rule that still applies
- Whatever collar you choose, follow that carton and ask a veterinarian if the cat is fragile or on other medication.
Hartz UltraGuard is the other cat collar already linked here. It is a different product. Do not move Seresto’s imidacloprid 10.0%, flumethrin 4.5%, 10-week age line, or 8-month replacement sentence onto it. This rebuild did not open a Hartz EPA stamp, so it does not print a Hartz month count or a Hartz age gate. A lower shelf price is not a shared registration. Read the carton you buy, and ask a veterinarian before using any pesticide collar on a debilitated, aged, breeding, pregnant, or nursing cat, or a cat on other medication.
Pros
- Naming it keeps a cheaper collar from being mistaken for the Seresto stamp
- The comparison is the registration, not the shelf position
Cons
- This page does not pretend the two collars share one EPA file
- No Hartz timing number is available from the sources opened here
What EPA published about incidents
EPA’s July 13, 2023 notice says the collars continue to meet the FIFRA standard. The same notice says approval is for five years so incident reports can be evaluated again, and that further action is possible. The public review says EPA looked at 1,400 death reports from 2016 through 2020, about 2 percent of Seresto incidents in those years. Many lacked details. The only deaths found probably or definitely related to use were mechanical strangulation or trauma, often when the release mechanism failed. EPA did not publish a chemical fatality percentage, and this page does not create one.
More common reports on the review page are itching in dogs and hair-coat changes near the collar in cats. Less common, more serious reports include neurological signs such as convulsions or ataxia. The cat stamp’s own list, in decreasing reporting frequency, starts with application-site reactions: hair change, lesions, pruritus, erythema, inflammation, hemorrhage, burns, self-trauma, and ulcers. Then behavioral disorders, lethargy, anorexia, vomiting, alopecia, hyperactivity, skin disorders, vocalization, skin lesions, and hypersalivation. Remove the collar if those occur. Report them to Elanco at 1-800-255-6826 or through EPA’s pet incident page.
Early scratching can happen in a cat that is new to collars. The stamp says mild hair loss and mild skin reactions at the site usually recover within 1 or 2 weeks without removal, and that the collar must not be fitted too tightly. Elanco’s US page says the same window, and says collar removal is the step when dermatitis, inflammation, eczema, or lesions show up. A white powder on a collar fresh from the pouch is described by Elanco as stearic acid from the mold, and it can be wiped off. Elanco also says a collar that ends up in the mouth is usually too loose. The two-finger fit is the correction. Elanco discourages taking the collar off for a couple of months and putting the same collar back later, because that pause was not studied and protection may change.
When a monthly topical is the other format
Choose the Seresto Cat collar when the cat is 10 weeks or older, a veterinarian is comfortable with this pesticide on this cat, the cat will keep neckwear on, and you will check the fit and the neck. Skip it when the cat is under 10 weeks, medically fragile, already reacted at a collar site, or will not stop escaping or chewing the band. Heartworm and intestinal parasites are a different conversation than this collar.
A monthly spot-on is a different EPA product. Read that tube’s species and weight lines. The related review is Frontline vs Advantage for cats. Never use a dog-only permethrin product, including K9 Advantix II or Frontline Shield, on a cat. A dog Seresto collar is a separate registration from 11556-191. Tell anyone who grooms or cares for the cat which preventative is already on, so a second pesticide is not stacked on a live collar by accident.
Choose Seresto Cat when
- Eight months of continuous labeled flea and tick control is printed on the cat directions
- Flea timing and the 48-hour new-tick window are specific
- The release mechanism and the two-finger fit are on the how-to-apply text
- EPA left the collar registered, with a public incident record you can read
Skip Seresto Cat when
- The adverse-event list includes skin injury and neurologic signs, and the collar comes off if they occur
- Death reports EPA could tie to use were mechanical, which makes fit and the release mechanism part of safety
- The registration is time-limited through 07/13/2028 unless extended
- A shopping collar next to it is not this stamp
Seresto cat collar FAQ
Did the EPA ban Seresto collars?
No. On July 13, 2023, EPA said these collars still meet the FIFRA standard and required extra mitigation: clearer adverse-event warnings, better incident follow-up, and outreach. EPA limited the approval to five years so incident data can be reviewed again. The cat registration notice expires 07/13/2028 unless extended. That is not a ban.
What is on the Seresto Cat stamp?
EPA Reg. No. 11556-191, dated 07/13/2023, lists flumethrin 4.5% and imidacloprid 10.0%. Directions cover cats and kittens 10 weeks and older, one collar, continuous wear, and replacement after 8 months. Elanco’s US cat page prints the same two percentages.
How soon does the collar address fleas and ticks?
On the product-information block: existing fleas are killed 24 hours after the collar goes on. After that, new fleas are killed within 2 hours for 8 months. Remove ticks already on the cat. Prevention of new tick infestations starts at 48 hours. New ticks are addressed as quickly as 6 hours after that 48-hour mark. An optional line on the same accepted file says existing ticks are killed at 48 hours. Keep the remove-at-fitting instruction.
When should the collar come off?
The stamp lists cat adverse events in decreasing order of reporting frequency: application-site reactions (hair change, lesions, pruritus, erythema, inflammation, hemorrhage, burns, self-trauma, ulcers), then behavioral disorders, lethargy, anorexia, vomiting, alopecia, hyperactivity, skin disorders, vocalization, skin lesions, and hypersalivation. Remove the collar if those occur and consult a veterinarian. The hotline on the stamp is 1-800-255-6826. Slight hair loss or mild skin irritation can clear in 1 or 2 weeks without removal. Neurological signs are not a wait-and-see list. EPA’s review page names convulsions and ataxia among less common, more serious reports.
Were the reported deaths a chemical finding?
EPA analyzed death reports for 2016 through 2020: 1,400 reports, about 2 percent of Seresto incidents in those years. Many reports lacked the detail needed to assign a cause. The only deaths EPA found probably or definitely related to product use were mechanical strangulation or trauma, often from release-mechanism failure. The 2 percent figure is the share of incident reports that mentioned death. It is not a chemical fatality rate, and this page does not invent one.
Does a bath shorten the 8 months?
The cat stamp reviewed here does not print a shorter month count after a bath, and it does not paste a dog-collar swim schedule onto the cat directions. Elanco’s US cat page says the collar does not have to come off when the cat gets wet, and that prolonged, intense water exposure or extensive shampooing may reduce how long protection lasts. Elanco does not name a replacement month count. Do not invent one.
Is a monthly topical the same decision?
No. Seresto Cat is an 8-month collar. A monthly spot-on is a different EPA product with its own carton, species line, and weight line. If the cat shreds collars or already had a collar-site reaction, that format belongs in the conversation. The comparison on this site is Frontline vs Advantage for cats. Do not put a dog-only permethrin product, including K9 Advantix II or Frontline Shield, on a cat. Dog Seresto is a separate registration from 11556-191.
Sources
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