Seresto collars contain two active ingredients—imidacloprid to target fleas and flumethrin to kill and repel ticks. Similar to topical treatments, these ingredients spread from a point of contact over your dog’s skin and coat, from head to tail, killing fleas within 24 hours and ticks within 48 hours of contact. But whereas topical treatments wear off or wash off over time, Seresto collars deliver a continuous concentration of the active ingredients for 8 months. That sustained, long-lasting protection is what makes Seresto different from prescription oral and topical treatments.
