Life-threatening neurotoxicity following off-label ivermectin use in metastatic breast cancer: a case report

BACKGROUND: The United States Food and Drug Administration (FDA) has explicitly discouraged the use of ivermectin for the treatment of cancer outside of clinical trials. Nevertheless, patient self-administration persists, frequently influenced by information encountered online. Cases of ivermectin neurotoxicity in the oncology setting remain underreported despite growing off-label use driven by online misinformation. We present a case of severe neurotoxicity following unintentional high-dose self-administration of ivermectin as an off-label attempt to treat breast cancer. CASE PRESENTATION: A 73-year-old female with metastatic breast cancer self-administered high doses of ivermectin based on information obtained online. She subsequently developed acute altered mental status, generalized seizures, and respiratory failure. Her clinical course was consistent with severe ivermectin-induced neurotoxicity, necessitating supportive management including intubation, mechanical ventilation, intravenous fluids, and anticonvulsant therapy. The patient demonstrated full neurological recovery to baseline within 48 hours. CONCLUSION: This case highlights the potential for life-threatening neurotoxicity associated with high-dose ivermectin use. Increasing online health misinformation has led to the self-administration of unproven therapies; therefore, clinicians should counsel patients on the risks of non-evidence-based treatments. A thorough exposure history is essential to identify uncommon causes and maintain vigilance for severe adverse reactions.