How long does it take for rat poison to start working? - briefly
Most rodent anticoagulants begin to affect the animal within 24 hours, with lethal effects usually appearing after 2–5 days as blood clotting diminishes. Faster-acting neurotoxic poisons can cause symptoms in a few hours, but death still may take several hours.
How long does it take for rat poison to start working? - in detail
The effectiveness of rodenticide depends on its active ingredient, the method of delivery, and the condition of the target animal. Most anticoagulant baits, such as bromadiolone, brodifacoum, and difenacoum, begin to interfere with blood clotting within a few hours after ingestion. Clinical signs of internal bleeding typically emerge between 24 and 72 hours, and mortality often occurs during the second or third day.
First‑generation compounds (e.g., warfarin, chlorophacinone) act more slowly. After a single dose, observable effects may not appear until 3–5 days, and multiple feedings are usually required to achieve a lethal dose. Second‑generation agents are more potent; a single feeding can be sufficient, and death may follow within 1–3 days.
Key variables influencing the timeline:
- Dose size – larger amounts accelerate the onset of toxicity.
- Species and health status – younger, smaller, or already weakened rodents succumb faster.
- Environmental temperature – higher temperatures increase metabolic rates, shortening the delay.
- Formulation – liquid baits are absorbed more quickly than solid pellets.
Typical progression after consumption of a potent anticoagulant:
- 0–12 hours: Absorption and distribution of the toxin; no external symptoms.
- 12–48 hours: Disruption of the vitamin K cycle; internal bleeding begins.
- 48–72 hours: Accumulation of blood loss leads to lethargy, bruising, and eventual collapse.
- 72 hours onward: Death usually occurs if the dose is lethal; survivors may recover if sublethal.
Non‑anticoagulant poisons (e.g., zinc phosphide, bromethalin) follow different patterns. Zinc phosphide releases phosphine gas in the stomach, causing rapid organ failure; death can occur within 6–12 hours. Bromethalin interferes with neuronal energy production; neurological signs appear after 24–48 hours, with mortality often within 3–5 days.
In practice, monitoring bait stations for 4–7 days ensures that most targeted rodents have been affected. Persistent activity beyond this window suggests either insufficient bait uptake or resistance, requiring a reassessment of dosage, bait type, or placement strategy.