Are there published case reports of ivermectin poisoning from horse dewormer between 2020 and 2024?

1. Spike in poison‑control reports put the problem on the map in 2021

Poison‑control centers and the CDC recorded a rapid increase in human exposures to ivermectin in mid‑2021, coincident with public interest in using the drug for COVID‑19. The CDC Health Advisory dated August 26, 2021, documents specific severe cases after ingestion of veterinary formulations intended for large animals and warns that veterinary products are highly concentrated and associated with overdoses ^[4]. Contemporary reporting and poison‑center data described hospitalizations for confusion, ataxia, seizures, and hypotension tied to veterinary products, and noted that many callers had obtained livestock formulations or injectable products meant for cattle or horses ^{[5] [6]}. Public health agencies framed these exposures as preventable harms stemming from off‑label self‑medication.

2. Peer‑reviewed case series quantified the burden and identified veterinary products as higher‑risk

A retrospective case series published in Clinical Toxicology (data collection Aug 14, 2021–Jan 31, 2022) documented 37 cases of ivermectin toxicity reported to a regional poison center, 17 of which involved veterinary formulations (horse dewormer paste or liquid), and these cases showed higher doses and more frequent altered mental status ^[1]. That peer‑reviewed analysis provides clinical details—symptom profiles, hospitalization rates, and formulation types—and confirms that veterinary products were disproportionately represented among serious exposures during the pandemic period. Subsequent summaries and database analyses repeated this pattern, reinforcing that veterinary ivermectin was a common vector for overdose in this timeframe ^[2].

3. Individual case reports show rare but severe outcomes from veterinary formulations

Beyond aggregated surveillance, there are published individual case reports documenting severe neurotoxicity after administration of veterinary ivermectin. One report describes a 50‑year‑old woman who received intravenous veterinary ivermectin for COVID‑19 and developed profound neurotoxicity requiring intensive care; the clinical narrative illustrates how non‑human formulations and non‑approved routes of administration can cause severe harm ^{[3] [7]}. These case reports provide mechanistic and clinical confirmation that veterinary formulations are not interchangeable with human formulations and can lead to ICU‑level toxicity.

4. Older literature and non‑relevant records do not contradict recent findings but clarify scope

Historical reports of human exposures to veterinary ivermectin exist (for example a pre‑2020 case series), but they fall outside the 2020–2024 window and therefore do not alter the recent evidence base ^[8]. The distinction matters because the surge documented in 2021 was temporally linked to pandemic‑era behavior; older case reports show that veterinary exposures can occur, but the 2020–2024 literature specifically captures the pandemic‑related spike and its clinical consequences ^[6].

5. Multiple perspectives, public‑health framing, and potential agendas in reporting

Medical journals and public‑health agencies presented the data as warnings against self‑medication and misuse of veterinary products, emphasizing clinical risk and the concentrated dosing of livestock formulations ^{[1] [4]}. Some media and advocacy outlets highlighted individual stories to argue for stricter regulation or better public messaging; others framed incidents as consequences of misinformation about COVID‑19 treatments. These differing emphases reflect distinct agendas—patient safety and regulatory caution versus critiques of health communication—but they converge on the factual conclusion that veterinary ivermectin exposures increased during 2021 and resulted in documented poisonings through 2024 ^{[1] [4] [3]}.

Conclusion: multiple peer‑reviewed studies, federal advisories, poison‑center case series, and individual case reports published between 2020 and 2024 document ivermectin poisoning from veterinary (horse/livestock) formulations; the strongest evidence is a November 2022 peer‑reviewed case series and contemporaneous CDC advisories and case reports from 2021 that together establish the phenomenon and its clinical seriousness ^{[1] [4] [3]}.