Updated September 25, 2026. Fact-checked against veterinary sources; review by a licensed veterinarian is in progress. See our editorial policy.
Quick answer: The Seresto collar for dogs contains imidacloprid and flumethrin and is designed to kill and repel fleas and ticks for up to 8 months. It doesn’t prevent heartworm. In 2021, reports of adverse incidents in pets drew public and regulatory scrutiny, and the EPA reviewed the product. Many dogs use it without problems, but it’s worth knowing the signs of a reaction and discussing options with your vet.
What it covers
- Fleas
- Ticks
- Not heartworm or intestinal worms. Your dog still needs a separate heartworm preventive
Safety tips
- Fit the collar so two fingers slide underneath, and trim excess length
- Check the skin under the collar regularly
- Remove the collar and call your vet if you see skin irritation, hair loss, vomiting, lethargy, or neurological signs
- Keep children from playing with the collar, and wash hands after handling
- Use only products labeled for your pet’s species
- Buy from reputable sources. Counterfeit collars have been reported
Alternatives
- Monthly or longer-acting oral flea and tick chews (some combined with heartworm prevention, such as Simparica Trio)
- Topical spot-on products
- Other veterinary-recommended collars
Choosing
Consider your dog’s health history, swimming habits, household (children, cats), and local tick risks. Your vet can help you balance effectiveness and safety.
Sources
- US Environmental Protection Agency (EPA): Seresto pet collar information and review
- Elanco: Seresto for dogs product label
- Companion Animal Parasite Council (CAPC): Fleas and ticks
This article is for general education and is not a substitute for care from your own veterinarian. Learn about The Pet Vet and our editorial policy.