Ivermectin to Treat Cancer - Quick Reference Sheet
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Ivermectin to Treat Cancer

Created on 09/27/2026 – Quick Reference based on Evidence Review created using AI4L / Opus 5.5 – Audit

Ivermectin, a long-established medication for parasitic worm infections, is used by many people with cancer. Laboratory and animal studies show it can slow or kill cancer cells, but human evidence is limited to one small trial, a self-reported group study and scattered cases, so its effect on tumor control or survival remains unknown. Higher doses risk brain and nerve side effects; replacing proven treatment carries the largest potential harm. (Full Review)

Protocol

Continuous integrative regimen (Paul Marik, Independent Medical Alliance)
0.2–0.4 mg/kg daily
Usually starting at 0.3 mg/kg; titrated to a 0.8–1.0 mg/kg ceiling on progression
Pulse dosing (integrative practitioners, summarized by Paul Marik)
0.4 mg/kg daily for 5 days every 2–4 weeks
Or 0.3–0.6 mg/kg three times weekly; mainly after remission to limit cumulative exposure
Half-life and food
Taken the same way daily
Plasma half-life about 18 hours; a fatty meal raises exposure 2.6-fold
Time to effect
Tumor control
Within 2–3 months
Any benefit would be expected in this window; trials judge response on imaging every 6–12 weeks
Symptom relief
After several doses
Self-reported by cancer patients using ivermectin; uncontrolled

Benefits

Contraindications
  • Loa loa infection above 8,000 microfilariae/mL (highest danger above 50,000/mL)
  • Pregnancy (especially first trimester) and breastfeeding
  • ABCB1 loss-of-function variants or prior ivermectin neurotoxicity
  • Severe liver impairment (Child-Pugh class C)
  • Children weighing less than 15 kg
  • Strong CYP3A4 or P-glycoprotein inhibitors that cannot be stopped
  • Active central nervous system disease that disrupts the blood-brain barrier (e.g., meningitis)
    •
Key Interactions
  • Strong CYP3A4 inhibitors (ketoconazole, itraconazole, clarithromycin, ritonavir)
  • P-glycoprotein inhibitors (verapamil, amiodarone, cyclosporine, quinidine)
  • Oral kinase inhibitors (regorafenib, sorafenib)
  • Warfarin (a blood thinner)
  • CYP3A4 inducers (rifampin, carbamazepine, phenytoin, St. John's wort)
  • Benzodiazepines (lorazepam), barbiturates (phenobarbital), over-the-counter sedating antihistamines (diphenhydramine, doxylamine), alcohol and sedating supplements (valerian, kava, high-dose melatonin)
  • Grapefruit juice (a CYP3A4 inhibitor) and supplements inhibiting CYP3A4 or P-glycoprotein (piperine, curcumin, quercetin, green tea extract)
  • Other antiparasitic drugs (mebendazole, fenbendazole)
  • Checkpoint inhibitors (pembrolizumab, balstilimab)
  • High-fat meals
    •

Risk & Side Effects

  • High:
  • Medium: Brain and nerve toxicity at high or accumulated doses; severe reactions in people with heavy Loa loa infection
    •
  • Low: Mild digestive, visual and skin side effects; forgoing or delaying effective cancer treatment; drug-induced liver injury; severe skin reactions
    •
  • Speculative: Weaker immunotherapy response through gut bacteria disruption; higher chemotherapy toxicity through pump inhibition
    •

Monitoring

Marker Target Why
ALT 10–26 U/L Detects liver injury
AST 10–26 U/L Confirms liver injury pattern
Total bilirubin 0.3–1.0 mg/dL Shows impaired liver clearance
CBC White cells 5.0–8.0 ×10⁹/L; platelets 150–350 ×10⁹/L Tracks marrow reserve
Creatinine and eGFR eGFR above 90 mL/min/1.73 m² Guides dosing of co-medications
INR (warfarin users only) Individual target, usually 2.0–3.0 Detects interaction-driven bleeding risk
Tumor markers (CEA, CA 15-3, CA-125, PSA) No established target; track change from own baseline Early signal of response or progression
Imaging (CT, MRI or PET) No functional target; stable or shrinking lesions versus baseline Defines tumor control
Strongyloides serology Negative Excludes hidden threadworm infection
Loa loa blood smear 0 microfilariae/mL (must be below 8,000) Excludes encephalopathy risk

Cadence: Baseline before starting; liver tests and blood counts at 2 and 4 weeks, then every 2–3 months; INR 3–7 days after any dose change for warfarin users; tumor markers and imaging every 8–12 weeks

Qualitative Assessment

  • Vision: Blurred vision or altered color perception
  • Balance and coordination: New unsteadiness, tremor or falls
  • Alertness and memory: Drowsiness, confusion or slowed thinking
  • Energy and appetite: Changes relative to the pre-treatment baseline
  • Digestive tolerance: Nausea, diarrhea or abdominal pain
  • Cancer symptoms and function: Pain, breathlessness and ability to carry out daily activities
Not medical advice. Educational distillation of a single evidence review. Confirm any decision with a qualified clinician, especially in the presence of prescription drugs or chronic conditions.