How long does a Seresto collar last?

One Seresto collar lasts 8 continuous months. That single number shapes how you plan a whole flea and tick season.

8 months from one collar

The active ingredients, imidacloprid and flumethrin, are stored in the collar's polymer matrix and released over 8 months. During that time the collar kills and repels fleas and ticks by contact, so they do not have to bite your pet.

When does it start working?

Within 24 hours of putting it on. Put the collar on before the season starts in your area, not on the day you see the first flea.

Planning replacements

• Write the start date on the calendar or in your phone.
• Replace the collar 8 months later.
• Two pets of the same size: the 2-collar pack keeps both on the same schedule.
• Check the label in the box for how swimming and bathing affect duration.