What are the documented harms and poisonings associated with off‑label ivermectin use during the COVID‑19 pandemic?
Executive summary
Off‑label use of ivermectin during the COVID‑19 pandemic produced a measurable rise in poison‑control reports, emergency visits, hospitalizations, and some deaths tied to misuse, overdose, and ingestion of veterinary formulations, even as high‑quality trials showed no clinical benefit for COVID‑19 [1] [2] [3]. Case reports and pharmacovigilance reviews document gastrointestinal, neurologic and cardiopulmonary toxicity—including seizures, confusion, coma, hypotension and rare fatalities—while public misinformation and policy debates amplified misuse and constrained evidence‑based responses [4] [3] [5].
1. Surge in exposures and health‑system burden documented by poison centers
Multiple public‑health agencies and toxicology groups recorded sharp upticks in calls and cases: the CDC and state poison centers reported a marked increase in ivermectin exposures compared with pre‑pandemic baselines—one poison center's monthly calls rose from near zero to dozens in August 2021—and national dispensing of ivermectin prescriptions increased many‑fold during peaks of public interest [1] [6] [7]. The American College of Medical Toxicology noted a corresponding stream of clinical toxicity reports and cautioned against off‑label prescribing because these exposures produced real morbidity and diverted clinical resources [8].
2. Clinical picture: gastrointestinal to life‑threatening neurologic effects
The clinical spectrum of documented adverse events ranges from nausea, vomiting and diarrhea to severe neurologic effects such as confusion, hallucinations, ataxia, seizures, decreased consciousness, encephalopathy and coma; hypotension and interactions with other central‑nervous‑system depressants or anticoagulants were also reported, and several case series and VigiBase analyses identified hospitalizations and life‑threatening events [4] [3] [9]. Pharmacovigilance data in the WHO database included serious cases and a small number of deaths where ivermectin was the single suspect, and peer‑reviewed summaries emphasize both typical overdose syndromes and occasional idiosyncratic or interaction‑mediated neuropsychiatric events [3] [9].
3. Veterinary products and dosing errors amplified harms
A consistent theme in official alerts and case reports is the use of veterinary formulations—meant for large animals and frequently far more concentrated than human products—which led to overdoses and exposure to inactive ingredients not tested for human safety, a factor explicitly cited by state health departments and reflected in increased severe‑illness reports [10] [2]. Public guidance from the FDA and state health agencies warned that animal ivermectin preparations are unsafe for human use and documented cases where such misuse correlated with severe toxicity [2] [10].
4. Indirect harms: false reassurance, diversion of care and supply shortages
Beyond direct toxicity, authorities and commentators documented indirect harms: taking ivermectin instead of proven prevention or treatment (including vaccination) could delay care and worsen outcomes, clinicians warned that off‑label prescribing reduced availability for approved antiparasitic uses, and misinformation campaigns inflated demand and exposure risk—outcomes highlighted by the WHO, CDC and multiple medical societies [4] [5] [8]. The American Medical Association and allied pharmacy organizations explicitly opposed dispensing ivermectin for COVID‑19 outside trials because of these systemic and public‑health consequences [6].
5. Scientific consensus, contested narratives and agendas behind the harm signal
High‑quality randomized trials and major regulators (WHO, FDA, EMA, IDSA) found no reliable clinical benefit of ivermectin for COVID‑19, and pharmaceutical companies and public‑health bodies warned against use; nevertheless, advocacy groups, misinterpreted studies, and online campaigns promoted the drug, creating a feedback loop that increased off‑label prescribing and self‑medication—a dynamic noted in epidemiologic analyses and investigative reporting [11] [5] [12]. While some proponents argued for compassionate or trial use, clinical toxicologists and public‑health agencies emphasized documented harms and the lack of robust efficacy data [8] [3].
6. Limits of reporting and open questions for investigators
Available sources document increased calls, a range of toxic effects, hospitalizations, and some deaths associated with ivermectin misuse, but surveillance datasets and case reports cannot always determine causality, quantify the proportion of severe outcomes attributable to veterinary versus human formulations, or fully capture long‑term sequelae—issues flagged in pharmacovigilance reviews and editorials that call for rigorous, transparent case investigation and continued monitoring [3] [4]. Until comprehensive, linked clinical and toxicologic investigations are completed, public agencies will rely on the existing signal—rising exposures and concordant toxicity reports—to justify warnings and further research [1] [8].