What are the documented harms from people taking veterinary ivermectin formulations or overdosing on human ivermectin?

1. Documented spectrum of harms observed in humans

Case reports and poison-center summaries show a reproducible pattern: people who ingested veterinary products or took higher-than-recommended human doses developed gastrointestinal symptoms (nausea, vomiting, diarrhea), neurologic signs (dizziness, confusion, loss of coordination, seizures), cardiovascular problems (low blood pressure) and allergic or hepatic reactions; many of these cases required emergency care or hospitalization ^[4][5][3].

2. Neurologic toxicity is the clearest consistent danger

The dominant and most worrying cluster of effects is neurotoxicity — from transient dizziness and somnolence up to severe outcomes such as profound confusion, ataxia, seizures, depressed consciousness and coma — which occurs when ivermectin crosses into the central nervous system at high doses or when protective transporters are impaired ^[6][7][5].

3. Hospitalizations, poison-control trends and deaths during misuse waves

Multiple poison-control centers documented sharp spikes in calls in 2020–2021 linked to ivermectin misuse for COVID‑19; small observational series (e.g., Oregon Poison Center) reported dozens of calls and several hospitalizations, and some jurisdictions investigated fatal poisonings traced to ivermectin misuse ^[2][5][8].

4. Veterinary formulations pose added hazards beyond dose

Veterinary products are formulated for large animals and often contain much higher concentrations per unit and nonpharmaceutical excipients or solvents not tested for human safety; ingestion of such products has produced rapid overdose presentations and has been repeatedly singled out by regulators as especially dangerous ^[1][9][10].

5. Specific risk factors that amplify harm

Certain conditions amplify risk: genetic defects in the ABCB1 (MDR1/P‑glycoprotein) transporter can allow ivermectin into the brain causing encephalopathy after otherwise routine doses (documented in a pediatric case) and heavy Loa loa infection contexts are known to trigger severe neurologic reactions after ivermectin; advanced age, polypharmacy with CNS depressants, and repeated supratherapeutic dosing were common among reported toxic cases ^[11][12][13].

6. Clinical management and limits of evidence on antidotes

There is no specific antidote; treatment is supportive — airway and hemodynamic support, symptomatic care, and sometimes activated charcoal if ingestion is recent — and case literature suggests most patients improve with time and supportive therapy though severe cases require intensive care; experimental or veterinary-oriented interventions (e.g., intravenous lipid emulsion) have mixed or no consistent evidence in humans ^[14][10][4].

7. How common and how severe are these events in context?

While calls to poison centers rose markedly from a low baseline during the pandemic, many reports were mild and serious toxicity remained uncommon overall; nevertheless, repeated observational reports, WHO pharmacovigilance analyses and case series confirm a nontrivial number of hospitalizations, some severe neurologic events, and a small number of deaths associated with misuse or overdose ^[15][12][2].

8. Takeaway: documented harms and the evidence boundary

The documented harms from veterinary ivermectin ingestion or human overdose are well‑characterized and include gastrointestinal upset, pronounced neurotoxicity (seizures, coma), hypotension, allergic/hepatic reactions, hospitalization and rare deaths, with veterinary products adding concentration and excipient risks; the literature and public‑health advisories make clear that these outcomes are avoidable by using only approved human formulations at recommended doses and under medical supervision, and that long‑term effects are less well quantified in the available reports ^[1][3][5].