When do flea drops start working on cats? - briefly
A spot‑on flea product usually begins killing adult fleas on a cat within 4–6 hours, with most of the infestation cleared by 24 hours. Ongoing protection against new fleas lasts for the product’s labeled duration, typically one month.
When do flea drops start working on cats? - in detail
Flea spot‑on products applied to a cat’s skin begin to affect adult fleas within minutes. Most formulations containing imidacloprid, fipronil or selamectin start killing adult insects in 30 minutes to 4 hours after a single dose. The rapid absorption through the skin distributes the active ingredient via the bloodstream to the fur, where it contacts parasites feeding on the host.
The life‑stage timeline is as follows:
- Adult fleas: kill begins within 30 minutes, full efficacy reached by 4 hours.
- Eggs and larvae: interruption of the reproductive cycle occurs as adults die and stop laying. New eggs fail to hatch, and larvae die within 24–72 hours.
- Re‑infestation protection: the chemical remains at therapeutic levels for the product’s labelled duration, typically 30 days, preventing new adult fleas from establishing.
Factors influencing the onset include:
- Active ingredient: some compounds act faster (e.g., imidacloprid) than others.
- Cat’s weight and health: under‑ or overweight animals may receive sub‑optimal dosing, altering speed of action.
- Application site: proper placement on the back of the neck ensures optimal absorption; spreading the product over a larger area can delay distribution.
- Environmental temperature: higher ambient temperatures increase skin circulation, slightly accelerating the process.
A single application therefore provides immediate relief from existing adult fleas, eliminates eggs and larvae within three days, and maintains protection for a month, assuming correct dosing and adherence to the product’s usage instructions.