What clinical effects and symptoms have poison centers documented from ingesting veterinary ivermectin products?

1. Clinical picture reported by poison centers: neurotoxicity up front

The dominant clinical finding across poison‑center case series and health advisories is neurologic toxicity—confusion, altered mental status, loss of coordination or balance, drowsiness and central nervous system depression—which accounted for the majority of documented clinical effects in published analyses (neurotoxicity in 30 of the cases described) and in agency reports ^{[1] [2] [4]}.

2. Gastrointestinal, visual and cardiopulmonary symptoms that accompany neurologic signs

Alongside neuro signs, poison centers and public‑health advisories repeatedly list nausea, vomiting, abdominal pain and diarrhea; visual complaints such as blurred vision and visual hallucinations; dizziness, headache, tachycardia and hypotension; and in severe cases seizures or depressed consciousness—symptoms that appear in multiple CDC/IHS advisories and case compilations ^{[2] [7] [1]}.

3. Veterinary formulations amplify dose and severity

Investigators and regulatory notices single out veterinary products—pour‑ons, pastes and injectables—because they are far more concentrated or formulated for large animals, so typical human misuse results in large single doses or prolonged overdosing and therefore higher rates of altered mental status and more severe toxicity compared with prescription human tablets ^{[5] [6] [1]}.

4. Who became sick and how badly: demographics, hospitalizations, and worst outcomes

Published case series and NEJM reporting showed most affected individuals were older (median age in some reports ~64), predominately male, and many took ivermectin for COVID‑19 prevention or treatment rather than parasitic disease; of small cohorts reported, several required hospitalization for toxic effects though deaths were not the predominant signal in the poison‑center case series cited ^{[3] [4] [1]}. Federal advisories warn that seizures, coma and death have been reported in toxic‑dose exposures, and that severe outcomes increase when ivermectin is combined with other sedatives ^{[2] [8]}.

5. Mechanism and interactions explain the clinical syndrome

Ivermectin’s pharmacology—potentiation of inhibitory channels in nerve and muscle cells—produces the physiologic basis for paralysis‑like neurologic effects and sedation described in human toxicities; clinicians also warned about additive depressant effects when ivermectin is taken with benzodiazepines or barbiturates, which can worsen central nervous system depression ^{[8] [2]}.

6. Evidence limits, alternative readings and implicit drivers

The available evidence is descriptive and drawn largely from poison‑center reports, clinical toxicology series, and public‑health advisories—sources that capture symptomatic cases but not systematic denominators, so incidence and fatality rates cannot be precisely estimated from them ^{[1] [2]}. Alternative viewpoints emphasize that properly dosed, prescription ivermectin has established human uses and that not all adverse events stem from veterinary products, but the data consistently link misuse of concentrated animal formulations to larger doses and more severe presentations ^{[4] [3]}. Public‑health messaging and regulatory statements also reflect an implicit agenda to curb off‑label use during the pandemic, which influenced surveillance and reporting intensity ^{[7] [5]}.

7. Bottom line and practical implications from poison‑center experience

Poison‑center documentation paints a clear clinical syndrome from ingesting veterinary ivermectin: primarily neurologic dysfunction (confusion, ataxia, coma, seizures), with frequent GI, visual and cardiopulmonary symptoms; severity correlates with dose and with use of concentrated animal formulations, and cases rose during the COVID‑19 period prompting multiple health advisories and hospital admissions ^{[1] [2] [5]}. These sources recommend contacting poison control for management and caution that veterinary products often contain concentrations and inactive ingredients not evaluated for human use ^{[2] [6]}.