Drug-induced liver injury following co-ingestion of veterinary fenbendazole and ivermectin for prostate cancer: a case report
A 65-year-old man with prostate cancer took veterinary fenbendazole and ivermectin on alternate days for three months on the advice of online support groups and developed severe liver injury, which cleared six weeks after he stopped.
Overview
The patient presented with two weeks of fatigue, jaundice and abdominal pain after a three-month regimen of alternating veterinary-grade fenbendazole and ivermectin at 'one squirt' a day, estimated at 0.18 mg/kg of ivermectin and 0.98 mg/kg of fenbendazole (Powderly case report 2026). Alanine aminotransferase was 1764 U/L, aspartate aminotransferase 1132 U/L and bilirubin 12.9 mg/dL, viral, autoimmune and biliary causes were excluded, transaminases fell 58 percent within nine days of stopping and normalised within six weeks, and a RUCAM score of 9 rated the causal link 'highly probable' (Powderly case report 2026).
- Hepatocellular liver injury with bilirubin 12.9 mg/dL after three months of veterinary fenbendazole and ivermectin; RUCAM 9, highly probable.
- Resolved within six weeks of stopping both agents.
Veterinary paste is dosed for animals by weight, and 'one squirt' is not a human dose. Liver injury of this severity can be fatal and this patient was fortunate to present in time.
- Single case; the relative contribution of the two drugs cannot be separated.
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