What are the recognized symptoms of ivermectin overdose in adults and children?
Executive summary
Ivermectin overdose produces a spectrum of mainly neurological and gastrointestinal symptoms, ranging from dizziness, nausea and vomiting to confusion, ataxia, seizures and, rarely, coma or death [1] [2] [3]. Children and adults can both experience neurotoxicity at supratherapeutic doses, with case reports documenting pronounced visual disturbance and ataxia in pediatric overdoses and systematic reviews noting dose‑dependent exposure differences between children and adults [4] [5] [6].
1. Common early signs: gastrointestinal upset, headache and dizziness
The earliest and most frequently reported manifestations of excess ivermectin mirror many drug overdoses — nausea, vomiting, diarrhea, headache and dizziness — symptoms listed in drug information and clinical guidance as features of ivermectin overdose that require urgent evaluation [1] [7].
2. The dominant and dangerous theme: central nervous system effects
Beyond gastrointestinal complaints, the striking and dangerous cluster involves central nervous system effects — confusion, disorientation, somnolence, ataxia (loss of coordination), visual disturbances and in severe instances seizures or coma — all cited in clinical summaries and case literature as key signals of toxicity [2] [3] [4].
3. Pediatric presentations: case reports and what they reveal
Pediatric reports underscore how dramatic neurotoxic signs can be when children ingest veterinary formulations or many times the therapeutic dose; for example, a nine‑year‑old developed acute visual disturbances and ataxia after an estimated tenfold overdose, illustrating that children may present with prominent neurologic findings after supratherapeutic exposure [4]. However, controlled pharmacokinetic work shows children often achieve lower drug exposures than adults at the same weight‑based dose, complicating generalizations about susceptibility [5] [6].
4. Why the brain becomes vulnerable: mechanism and risk factors
Toxicity is plausibly linked to saturation of blood‑brain barrier transporters (MDR1/P‑glycoprotein), which normally limit ivermectin entry into the central nervous system; at very high doses these protective mechanisms may be overwhelmed, permitting concentrations that perturb neuronal receptors and trigger neurotoxicity [4]. Additional risk factors referenced in product information and safety reviews include use of formulations intended for animals, dosing errors, and underlying conditions that affect drug clearance or blood‑brain barrier function — though explicit epidemiologic quantification of these risks is limited in the cited sources [1] [2] [3].
5. Severity spectrum and rare outcomes: seizures, coma and fatalities
Authoritative drug resources and clinical reviews warn that while many cases are self‑limited with appropriate care, ivermectin overdose can progress to life‑threatening outcomes including seizures, coma and—in rare reports—death; product guidance therefore treats signs of neurotoxicity as medical emergencies requiring hospital management [2] [1] [3].
6. Practical clinical takeaways and gaps in the record
Clinicians and poison‑control guidance emphasize prompt medical assessment for any suspected overdose, with monitoring for neurologic decline and supportive care as mainstays; detailed treatment protocols are case‑by‑case and not fully detailed in the sources provided [1] [2]. Important gaps remain: pharmacokinetic data in small children are incomplete and ongoing studies aim to refine pediatric dosing and exposure risk, so absolute age‑based susceptibility statements should be made cautiously [6] [5]. The literature also repeatedly flags misuse of veterinary ivermectin as a driver of more severe poisonings, a pattern illustrated by several case reports [4] [3].