What are the risks and side effects of ivermectin overdose in people?
Executive summary
Ivermectin is safe when used at prescribed doses for approved parasitic diseases but overdoses can cause serious, sometimes fatal, effects including nausea, vomiting, low blood pressure, neurological problems (dizziness, ataxia, seizures), coma and death (FDA; Drugs.com) [1] [2]. Health agencies warn against using veterinary formulations or taking high/unsupervised doses for COVID-19 or other unproven uses because concentrated animal products and unsupported regimens have led to poisonings and emergency calls (Health Canada summary; AFP; FDA; Drugs.com) [3] [1] [2].
1. What an “overdose” looks like: the clinical picture
Overdose symptoms reported by regulators and drug references range from gastrointestinal upset (nausea, vomiting, diarrhea) and allergic reactions (itching, hives) to cardiovascular collapse (hypotension) and serious neurologic injury — dizziness, problems with balance (ataxia), seizures, coma and even death — all signs that large or inappropriate doses can affect multiple organ systems [1] [2] [4].
2. Why veterinary products are especially risky
Animal ivermectin products are far more concentrated and formulated for species with very different tolerances; using them orally or otherwise for people risks accidental overdose because a single veterinary dose can contain many times the approved human dose. Drug information pages and regulators explicitly warn not to take animal-intended ivermectin because of documented overdoses and poison center calls [2] [3].
3. The FDA and public-health warnings: context and emphasis
The FDA has not authorized ivermectin to prevent or treat COVID-19 and repeatedly warned that people can overdose, listing the full range of serious adverse events — from hypotension and seizures to coma and death — to discourage unsupervised use, especially the repurposing of non‑human formulations [1] [4].
4. Real‑world harms during the pandemic era
During COVID-19, prescriptions and nonprescription use of ivermectin surged; investigators and health systems documented increased calls to poison centers and higher outpatient prescribing, which in turn prompted repeated public advisories about self-medication and overdoses (UCLA analysis; AFP fact-check) [5] [3]. Independent reporting notes that alarm among clinicians rose when patients took unproven regimens, because there would be no benefit to offset the known risks [4].
5. What evidence says about routine or long‑term use
Doctors view approved, weight‑based doses for parasitic infections as generally safe, but long-term routine use outside those indications is not well studied; the FDA and clinicians say the risks of chronic or repeated unsupervised dosing are unknown and potentially serious [4] [2]. Available sources do not mention long-term safety data that would support repeated high‑dose use in humans (not found in current reporting).
6. Competing claims and why they matter
There remains a vocal minority promoting ivermectin for COVID-19 or cancer; some small or low‑quality studies and online anecdotes have been circulated suggesting benefit, while major clinical trials and systematic reviews have not established effectiveness for COVID‑19 and regulators continue to warn against off‑label mass use [6] [4]. Misinformation campaigns and politicization shaped public behavior and prescribing spikes, a factor public-health agencies explicitly cite when issuing safety warnings [5] [3].
7. Practical advice and the hidden agendas to watch
Experts and authorities uniformly advise: use ivermectin only for approved indications at prescribed doses, obtained from legitimate pharmacies, and never take veterinary formulations [1] [2]. Be alert that some advocates or commercial outlets pushing OTC access or high‑dose regimens may have ideological or financial motives; reporting shows legislation and online narratives influenced use patterns during the pandemic [7] [5].
Limitations: this briefing draws only on the provided sources; it does not attempt to summarize every clinical trial or toxicology report worldwide. For specific medical advice about an exposure or symptoms, sources recommend contacting emergency services or a poison control center [1] [2].