How does the Seresto collar work?

How does the Seresto collar work?

Vectors of serious diseases, fleas and ticks present themselves as enemies for our pets, but also for us, their owners. Not content with invading the coat of our cats and dogs, they attack us, while fleas form nests that proliferate and are difficult to get rid of. The Seresto collar is designed to counter this problem by repelling these invaders, without presenting undesirable side effects in the animal. Here's how it works. 

Seresto, German brand developed by Bayer

Seresto is a brand owned by the German pharmaceutical giant Bayer, founded in 1863. Its antiparasitic collar was phenomenally successful, in particular due to its wide range of action: it kills fleas in the larval stage, such as adults, as well as ticks, at all stages of their life cycle. (larva, pupa and adult).

seresto small dog collar
seresto large dog collar
seresto cat collar

Seresto has designed various ranges to meet the expectations of its customers. The collar is suitable for both cats and dogs. It is offered under different sizes to adapt to everyone's neck circumference and body mass. Cats and small dogs share the same range (with however differences in dosage), then you find a larger size for larger dogs (from 8 kilos). 

The field of use of the Seresto collar

The Seresto collar exerts its action for 7 to 8 months. It is designed for 

  • apply its action on parasites at all their stages of life, from larvae to adulthood;
  • the prevention of infestations by fleas in cats (Ctenocephalides felis) and dogs (Ctenocephalides canis); 
  • protection of the animal's immediate environment against the development of flea larvae (basket, floors, armchairs, woodwork, etc.);
  • an acaricidal action - therefore lethal - on ticks of the species Ixodes ricinus, Rhipicephalus sanguineus and Dermacentor reticulatus;
  • a repellent action on parasites already present, preventing them from feeding (ticks and fleas installed before treatment are killed within 48 hours);
  • indirect protection against the transmission of tick diseases;
  • the treatment of biting lice infestations (Trichodectes canis).

Composition and active ingredients of the Seresto collar for dogs 

The Seresto collar has the particularity of not releasing any odor, thanks to the selection of its active ingredients. 

The active ingredients of the Seresto collar

The Seresto collar contains two active substances: imidacloprid and flumethrin.


Imidacloprid is an external antiparasitic active against fleas in the larval and adult stages, as well as against lice. This neurotoxin operates as soon as the collar is applied to the Seresto for cats, whereas it only begins a few days later for the Seresto for dogs.

Imidacloprid acts on the central nervous system of fleas. It paralyzes them, then kills them. 


Flumethrin is an external parasiticide that acts on the nerve cells of parasites killing them after paralyzing them. It prevents the production of eggs by its lethal action on female ticks and operates a repellent action against ticks already present on the animal.


How does the Seresto collar work? 

The active ingredients of the Seresto collar are released slowly over eight months, which ensures the protection of the animal throughout this period. 

gradual release of active substances
Photo: Courtesy Bayer

The active substances spread from the site of direct contact over the entire skin surface. Thus, the whole body is treated. 

The water resistance of the Seresto collar

The Seresto collar is water resistant, allowing your pets to walk in the rain and bathe, without affecting its action. However, if you bathe your dog and shampoo him, you must remove the collar first. Otherwise, you reduce its longevity, because you subtract part of its active ingredients with the soap. 

Outside the bath, the collar must be worn constantly, 24 hours a day to be effective.

seresto water resistant necklace
Photo: Courtesy Bayer

Adverse reactions 

The Seresto collar does not produce any direct adverse effects on the animal. However, it should not be worn by a puppy under 7 months or a kitten under 10 months.

The only reservation to the use of the collar concerns pregnant and lactating females. In the absence of convincing results following laboratory tests, it seems preferable to avoid having the collar worn during this period.

Pet owners should be careful not to touch the collar and then bring their hand to their mouth or eyes. This can be problematic in the presence of children in particular. 

The solution is to slip the Seresto collar into a collar cover designed for this purpose. It prevents you from any contamination, but preserves the action of the pest control collar. As a bonus, it allows you to take advantage of a ring to attach your dog's leash and possibly a bell to prevent cats from chasing birds. For both, the collar cover allows you to attach the animal's medal, with its identification.

Our tips for using the pest control collar properly 

How to use the Seresto collar couldn't be simpler: take the collar out of its packaging and tie it around the animal's neck! He has to wear it 24 hours a day, unless you give him a soapy bath.

Adjust the collar: it should not be too loose so as not to be lost on walks, nor too tight for your pet's comfort. Position it by making a movement against the hair so that it is in direct contact with the skin of the animal.

If there is a long part sticking out, cut it off. On the other hand, if you use a collar cover, this superfluous part is not a problem, quite the contrary. Stuck it in the loops of the collar cover to take advantage of the active ingredients it contains.  

To take full advantage of the duration of action of the anti-flea and anti-tick collar, never take it out of its packaging in advance, but just before giving it to your dog or cat. After eight months of use, the collar must be discarded and cannot be reused. 

Beware of counterfeits!

Check the reliability of the site on which you are going to buy a Seresto collar. Like any pharmaceutical product, it is the subject of counterfeits which question the effectiveness of the collar, but also the safety for your animal, as for yourself if the fake flea product is aggressive. 

Our opinion on Seresto collars 

The Seresto collar is one of the effective, inexpensive (due in particular to its action over 8 months) and practical antiparasitic solutions. 

The efficiency is real. These antiparasitic collars have the advantage of preventing the onslaught of parasites by deterring them, but also by killing those who have nevertheless settled in the coat. They attack ticks and fleas at the larval stage, as well as adults, which guarantees total safety for the animal wearing the collar.

The only reservation concerning this solution is the danger for those around the animal in case of contact. However, it is quite normal for you to stroke your cat or dog, and even to indulge in hugs during which you rub your face against its soft coat. If you don't, your children certainly don't hesitate! This is why it is highly recommended to use a collar cover. It is all the more interesting that you keep it over the years, you just have to change the Seresto collar which is slipped inside. 

Put an end to tick-related illnesses, your pet's itching and the massively infested house with fleas, you can trust Seresto!

what does the seresto collar protect against
Photo: Courtesy Bayer

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