How common is drug-induced liver injury from ivermectin in humans?

1. Why the question matters: rare signal or growing problem?

Public concern about ivermectin‑related liver injury increased during the COVID‑19 pandemic as off‑label use rose; pharmacovigilance reports and case series subsequently recorded hepatic events. Pharmacovigilance data identify a signal but not incidence, meaning regulators and clinicians noted a pattern of reported hepatic disorders linked to ivermectin use for SARS‑CoV‑2, yet these systems cannot establish how frequently DILI truly occurs in exposed populations ^{[2] [4]}. The LiverTox summary characterizes ivermectin as causing minor, self‑limiting aminotransferase elevations and very rare clinically apparent liver injury, assigning a likelihood score that reflects possible but uncommon hepatotoxicity ^[1]. These differing framings—signal detection versus expert toxicology synthesis—explain why concern exists without clear population‑level rates.

2. What the pharmacovigilance data show and their limits

Global spontaneous reporting systems like VigiBase captured small numbers of serious hepatic disorders temporally associated with ivermectin, including hepatitis, hepatocellular injury, and cholestasis. One pharmacovigilance study reported six serious hepatic cases among reports tied to COVID‑19 use, and described 4.3% of 1,393 reports as serious overall, which highlights a detectable but numerically small cluster of events ^[2]. Spontaneous reports are subject to reporting bias, lack denominators, and often miss co‑medications or preexisting liver disease; therefore, pharmacovigilance signals identify suspicious patterns warranting investigation but do not yield reliable incidence or causality estimates on their own ^[4].

3. Case reports show severe outcomes but reflect atypical circumstances

Multiple case reports document severe liver injury and even acute liver failure after misuse of veterinary formulations or self‑administration of ivermectin for COVID‑19 prevention or treatment. Reported instances include self‑injection of horse ivermectin and short‑course high‑dose self‑medication leading to liver failure, demonstrating that inappropriate formulations, unregulated dosing, and delays in seeking care can culminate in severe hepatotoxicity ^{[5] [3]}. Case series of self‑medication episodes found recovery after drug cessation in several patients, reinforcing that observed severe outcomes are often linked to misuse or extreme exposures rather than routine, supervised dosing ^[3].

4. Vulnerable populations and misinformation amplify the risk picture

Reports emphasize that populations affected by misinformation, including people with psychiatric disorders or those seeking unapproved remedies, are particularly at risk for harm from self‑administered ivermectin. A November‑December 2022 case report specifically highlighted patients with schizophrenia‑spectrum disorders who developed ivermectin‑related liver failure, underscoring how misinformation and impaired decision‑making can convert a rare adverse effect into a clinically significant event at the individual level ^[6]. These accounts illustrate that risk is not evenly distributed: misuse, comorbidities, and lack of medical supervision increase the probability of serious hepatic outcomes compared with supervised therapeutic use.

5. Why we cannot produce a precise incidence rate from available data

Available sources consistently demonstrate rarity but provide no reliable denominator for calculating incidence: spontaneous reporting systems lack exposure data, case reports are anecdotal, and published series focus on self‑medication contexts. Authoritative toxicology reviews classify ivermectin as a possible rare cause of clinically apparent liver injury, which reflects limited case evidence rather than quantified frequency ^[1]. Confounders in reported cases—concurrent medications, preexisting liver disease, incorrect formulations, and high or repeated dosing—complicate causal attribution and prevent derivation of population‑level risk estimates from the current literature ^{[4] [3]}.

6. Bottom line for clinicians and the public: rare risk, watchful approach

Ivermectin‑associated DILI is uncommon but real, with the clearest risks arising from misuse, off‑label high‑dose regimens, and vulnerable patients influenced by misinformation; ordinary, guideline‑directed therapeutic use in approved indications carries low documented risk according to toxicology summaries ^{[1] [2] [3]}. Clinicians should counsel patients against veterinary or unapproved products, monitor liver enzymes when ivermectin is used off‑label—especially in those with underlying liver disease or polypharmacy—and report suspected hepatic adverse reactions to pharmacovigilance systems to improve the evidence base ^{[2] [4]}.