Frontline Plus Purple for Large Dogs 20–40kg is a 3-pack of monthly spot-on flea and tick treatment dosed for the large-breed weight tier. It kills fleas, prevents flea eggs and larvae from developing, and controls paralysis ticks, brown dog ticks, and biting lice.

Each pipette delivers fipronil and S-methoprene: fipronil provides the fast-acting kill on adult fleas and ticks, while S-methoprene stops eggs and larvae from maturing in the dog's surroundings. Applied to the back of the neck once a month — guaranteed to kill 100% of fleas and larvae within 24–48 hours. In paralysis tick areas, fortnightly reapplication is recommended. Safe for puppies from 8 weeks of age.

Large-breed dogs accumulate more environmental parasite exposure through walks, gardens, and outdoor play, which is why consistent monthly treatment matters. Frontline Plus's combination of contact kill and environmental life-cycle control is designed to prevent the kind of re-infestation that plagues interrupted treatment schedules.