How do flea drops kill fleas? - briefly
Flea spot‑on products deliver insecticidal compounds (e.g., imidacloprid, fipronil) that are absorbed through the animal’s skin and spread across the coat, where they interfere with the parasite’s nervous system, causing swift paralysis and death. The agents persist on the skin and in the surrounding environment, eliminating fleas that contact the treated host for several weeks.
How do flea drops kill fleas? - in detail
Flea spot‑on treatments work by delivering an insecticidal compound that is absorbed through the animal’s skin and distributed via the bloodstream. Once in circulation, the chemical reaches the flea’s nervous system during a blood meal, causing rapid paralysis and death.
The process unfolds in several stages:
- Application and absorption – A few drops are applied to the dorsal neck area. The solvent evaporates, leaving the active ingredient in contact with the skin. Lipophilic properties enable the compound to penetrate the epidermis within minutes.
- Systemic distribution – The substance enters the capillary network and spreads throughout the host’s plasma. Because the animal’s body temperature and circulatory rate are constant, the medication reaches a steady concentration within an hour.
- Ingestion by the parasite – When a flea attaches to feed, it ingests blood containing the toxin. The dose is proportional to the flea’s size and feeding duration, ensuring lethal exposure even for immature stages.
- Neurotoxic action – Most modern formulations contain either neonicotinoids (e.g., imidacloprid), spinosyns (e.g., spinosad), or insect growth regulators (e.g., pyriproxyfen). These agents bind to nicotinic acetylcholine receptors or disrupt neurotransmitter release, producing uncontrolled nerve firing, loss of coordination, and eventual cessation of respiration.
- Secondary effects – Some products also incorporate insect growth regulators that prevent egg hatching and larval development, breaking the life cycle and reducing environmental flea pressure.
The combination of rapid systemic uptake, targeted neurotoxicity, and, when present, disruption of development ensures that the administered drops eliminate existing fleas and suppress future infestations.