How does FRONTLINE® Spot On work?

FRONTLINE Spot On acts by direct contact with parasites and not via your pet’s bloodstream. It kills fleas within 24 hours without requiring them to bite your pet.

  1. FRONTLINE Spot On is applied externally to your pet’s skin on the back of the neck.
  2. The active ingredient, fipronil, quickly dissolves into the natural oils of your pet’s skin and coat, dispersing over the entire body surface within 24 hours and concentrating in the skin's oil glands to form a reservoir.
  3. Fipronil is then secreted with the natural oils of the skin and hair, continuously coating your pet’s skin and hair for several weeks after application – in fact it’s the longest-lasting spot on flea treatment available without prescription.


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