What risks are associated with using veterinary ivermectin in humans (contaminants, dosing errors) in 2020-2023 reports?
Executive summary
Reports from 2020–2023 repeatedly warned that people taking veterinary ivermectin face two related risks: overdosing because animal formulations are far more concentrated than human tablets, and exposure to untested additives/contaminants in veterinary products; poison-centre and hospital reports document increased calls and some hospitalizations tied to animal-use ivermectin [1] [2] [3]. Regulatory and medical bodies — FDA, CDC, WHO and national health agencies — advise against using veterinary ivermectin for COVID-19 because safety and dosing for humans are not established and harms including nausea, hypotension, seizures, coma and death have been reported [4] [5] [6].
1. Veterinary vs. human formulations: concentrated doses and different vehicles
Veterinary ivermectin products are formulated for livestock and often contain higher concentrations and delivery vehicles [3] [7]. Clinicians and poison centres warned that amounts intended for horses or cattle can deliver “large amounts” to a person and that such dosing errors often underlie the majority of toxicity reports seen during 2020–2023 [3] [1].
2. Dosing errors and clinical toxicities recorded in 2020–2023
Surveillance and case-series during the pandemic showed an uptick in poison-control calls and clinical toxicity after self-administration of veterinary ivermectin; one poison-centre cluster led to 21 calls in a month and multiple hospitalisations for toxic effects, with reported manifestations including gastrointestinal symptoms, low blood pressure, neurologic effects (dizziness, ataxia, seizures), coma and death in extreme cases [1] [2] [4].
3. Contaminants and unlabeled ingredients: what reports say — and what they do not
Health agencies cautioned that veterinary products may contain additives or preservatives not evaluated for human ingestion, and that unauthorized animal products sold for human use might list ingredients inaccurately or omit hazards [8] [1]. Specific contaminant chemical-analyses in seized veterinary ivermectin meant for human use are not detailed in the cited reporting; available sources do not mention laboratory-confirmed lists of contaminants in veterinary supplies consumed by people [8] [1].
4. Pharmacology and why higher doses are dangerous
Ivermectin’s safety margin in humans depends on dose and the blood–brain barrier efflux transporter P‑glycoprotein; at high exposures more drug can penetrate the CNS and cause severe neurologic toxicity. Authors warned that antiviral effects seen in vitro would require concentrations above safe human dosing, so people attempting to reach those levels risk systemic toxicity [9] [10].
5. Drug interactions and vulnerable groups noted in reports
Regulatory guidance and clinical reviews stress that even approved human doses can interact with drugs (for example, warfarin) and that older patients or those with liver/kidney impairment may be at greater risk if dosing is inappropriate; reports showed many callers were older adults (median age 64 in one cluster) who had self-medicated for COVID-19 prevention [4] [2] [11].
6. Public-health consequences: spikes in calls, inappropriate prescriptions, and mixed messaging
Multiple sources documented a pandemic-era surge in ivermectin interest, a 72% increase in prescriptions in some analyses, and nations or jurisdictions that distributed ivermectin kits — all of which amplified exposure to off-label and veterinary formulations; poison-control volume and hospital admissions rose accordingly [12] [13] [1].
7. Competing perspectives and limitations in the record
Health agencies and toxicologists uniformly caution against animal-use ivermectin and document harms [4] [6]. Some clinical literature and advocacy note that ivermectin is safe at approved human doses for parasitic diseases and that severe adverse events are rare when prescribed correctly [14] [15]. The sources differ on causality for some pandemic-era observational claims of benefit; randomized large trials later found no clinical benefit for COVID-19, undercutting the rationale many used to justify self-medication [16] [5].
8. Practical takeaways and what reporting recommends
Regulators and major medical centres advised: do not use veterinary ivermectin for COVID-19; seek approved human formulations only under clinician guidance; contact poison control or emergency services for suspected overdose. The reports emphasize that contamination risk, undisclosed concentrations and the documented frequency of dosing errors together make veterinary products unsafe for human self-administration [4] [3] [1].
Limitations: the cited material gives strong surveillance, regulatory and case-report evidence of harms and dosing risks [1] [2] [4], but detailed analytical chemistry data on specific contaminants found in veterinary products consumed by humans are not provided in these sources — available sources do not mention laboratory-confirmed contaminant lists for such products [8] [1].