Cholecalciferol — yes, it is literally Vitamin D3 — is used as a rodenticide at extremely high doses. It causes fatal hypercalcemia (calcium overload) in rodents within 3-4 days. It is gaining popularity as anticoagulant rodenticides face increasing restrictions due to secondary poisoning concerns.
Rats and mice. Less commonly used for other rodents. Requires multiple feedings over 2-3 days for lethal dose in most formulations — not a single-feed kill like zinc phosphide or bromethalin.
Terad3 Blox (Bell Labs — the dominant brand), d-Con (some formulations contain cholecalciferol), Selontra (BASF — professional, contains cholecalciferol). Growing number of products as anticoagulant alternatives.
The irony: Vitamin D3 is essential for human health at normal doses (400-4000 IU/day) but lethal to rodents at the doses in bait (40,000-60,000 IU/gram). However, concentrated rodenticide bait is absolutely toxic to pets and humans if ingested.
Why it's growing in popularity: Cholecalciferol has lower secondary poisoning risk than second-generation anticoagulants. A predator that eats a poisoned rodent receives a fraction of the lethal dose. This makes it preferred in areas with endangered raptors or other wildlife.
Speed: Death typically occurs 3-4 days after lethal dose ingestion. Rodents become lethargic and seek water before dying. This is slower than zinc phosphide or bromethalin but faster than first-generation anticoagulants.
Resistance: No known resistance in any rodent population — a significant advantage over anticoagulant rodenticides, which face widespread resistance in some rat populations.