How long after applying drops do fleas die on a cat? - briefly
Most adult fleas are killed within 4–6 hours of a topical application, and the full infestation is generally eliminated within 12 hours. The medication remains effective for the product’s advertised period, typically up to one month.
How long after applying drops do fleas die on a cat? - in detail
Topical flea treatments begin killing parasites within minutes of contact with the cat’s skin. Most products containing fipronil, imidacloprid, or selamectin start affecting fleas in 5–10 minutes, causing paralysis and death shortly thereafter. Visible dead insects typically appear on the animal or in the environment within 1–2 hours.
Key factors that influence the speed of action:
- Active ingredient: Faster‑acting compounds (e.g., imidacloprid) produce mortality sooner than slower‑acting ones (e.g., selamectin).
- Dosage relative to body weight: Correct dosing ensures sufficient concentration on the skin; under‑dosing delays efficacy.
- Cat’s coat condition: Dense or matted fur can impede distribution, extending the onset period.
- Environmental temperature: Warm conditions accelerate the chemical’s spread; cold environments may slow it.
Typical timeline after a single spot‑on application:
- 0–10 minutes: Chemical spreads across the skin surface; fleas begin to experience nervous‑system disruption.
- 10–30 minutes: Most adult fleas lose mobility; many drop off the animal.
- 30 minutes–2 hours: Majority of visible fleas are dead; some may remain attached but are incapacitated.
- 2–24 hours: Residual activity eliminates newly emerged fleas from the cat’s environment; re‑infestation risk diminishes sharply.
If live fleas are still observed after 24 hours, verify that the correct product and dosage were used, and consider environmental control measures such as washing bedding and treating the home. Re‑application should follow the label’s recommended interval, usually every 30 days, to maintain continuous protection.