What are the acute symptoms of ivermectin poisoning in humans after taking veterinary formulations?
Executive summary
High-dose or veterinary ivermectin exposures in humans produce a consistent pattern of acute effects dominated by neurologic symptoms (confusion, decreased consciousness, seizures, coma) and gastrointestinal complaints (nausea, vomiting, diarrhea); neurotoxicity was the most frequently reported clinical effect in a case series (30 of 31 patients) and CDC/poison‑center alerts list seizures, hypotension and coma as documented overdose consequences [1] [2]. Poison‑control and public‑health reporting during the COVID era show a clear rise in cases tied to people ingesting veterinary products or excessive dosing of human tablets [3] [2].
1. Neurotoxicity is the signature acute harm — what clinicians saw
Case reports and poison‑center surveillance repeatedly identify central nervous system effects as the leading problem after veterinary or excessive ivermectin ingestion: patients developed decreased consciousness, confusion, hallucinations, seizures and coma; a PubMed case series summarized neurotoxicity in the majority of affected patients (neurotoxicity 30 of the reported clinical cases) [1]. The CDC health alert explicitly lists neurologic effects including decreased consciousness, confusion, hallucinations, seizures and coma as clinical effects of overdose [2].
2. Gastrointestinal and cardiovascular problems accompany neurologic signs
Acute overdoses produced a predictable package of symptoms: nausea, vomiting and diarrhea were repeatedly reported in surveillance and guidance documents, and hypotension has been recorded in severe poisonings [2]. American Hospital Association reporting of the CDC alert reiterated that clinical effects can range from gastrointestinal symptoms to hypotension along with neurological effects [4].
3. Veterinary formulations amplify risk — concentration and formulation matter
Public‑health agencies and clinical reviewers emphasize that veterinary ivermectin is designed for large animals and is more concentrated or in forms (pastes, pour‑on liquids, injectables) not intended for human dosing; that increases the risk of toxic ingestions when people attempt self‑treatment [5] [6]. Poison‑control calls frequently involved people who bought animal products or used topical/other non‑oral veterinary forms, and these exposures spike calls and hospital visits [3] [2].
4. Who got sick and how the exposures typically occurred
Surveillance during the pandemic found most callers were older adults and many took ivermectin to prevent or treat COVID‑19; case series and poison data show exposures came from intentional self‑medication (large single doses or repeated high daily doses) rather than accidental low‑level exposure [1] [3]. The PubMed review noted patients who ingested veterinary products often took large single doses or repeated large doses over days and developed rapid neurotoxic syndromes [1].
5. Outcomes and severity: hospitalizations, critical events, and rare deaths
Reports to poison centers and the CDC documented hospitalizations and severe outcomes including seizures, coma and in the most extreme cases death; the CDC health advisory explicitly links overdose to seizures, coma and death [2]. The New England Journal of Medicine and other analyses documented increased calls and clinically significant cases during COVID‑19 despite lack of evidence that ivermectin prevents or treats SARS‑CoV‑2 [3].
6. Scientific and public‑policy context: why people did this and what authorities said
Interest in ivermectin for COVID‑19 — despite randomized trials showing no clinical benefit and official non‑approval for COVID use — fuelled off‑label and self‑medication behaviors; the FDA and medical societies warned against using veterinary products and against unproven human use for COVID‑19 [5] [7]. Analyses and reporting link social‑media amplification and political shifts to surges in prescriptions and consumer demand, which in turn coincided with rising poison‑center contacts [3] [8].
7. Limitations and gaps in reporting
Available sources document acute clinical syndromes and poison‑center trends but do not provide a precise incidence rate of veterinary‑formulation poisonings nationwide or exhaustive dose–response thresholds for every formulation (available sources do not mention exact population‑level incidence or comprehensive dose cutoffs). Some literature aggregates mixed exposures (human and veterinary formulations), so comparing absolute risks across formulations is imperfect [1] [9].
8. Practical takeaway and where to seek help
Do not ingest veterinary ivermectin. If someone has taken veterinary or excessive ivermectin and develops nausea, vomiting, confusion, drowsiness, seizures or fainting, seek emergency care or call poison control immediately (US Poison Control 1‑800‑222‑1222); health authorities warn that such exposures cause neurotoxicity, hypotension and other life‑threatening effects [2] [4].
Sources cited above include FDA and CDC guidance, poison‑center analyses and peer‑reviewed case series documenting the acute symptom profile and public‑health impact of veterinary‑ivermectin exposures [5] [1] [3] [4] [2].