The Ivermectin and Fenbendazole Cancer Doses One Oncologist Uses

Source note: the dosing described here comes from a recorded interview with an oncologist who has advised more than a thousand patients on ivermectin and benzimidazole use through a private cancer coaching practice. He states plainly that this is not established pharmacology — there has never been a dose-finding trial for either drug in cancer. Nothing in this article is a recommendation; it is a record of what one clinician reports using, offered for the reader who wants to understand what the "protocol" everyone references actually consists of.

Why there is no chart to copy

Asked directly whether this dosing reflects established pharmacology, the physician's answer was no — this is not established pharmacology. What exists instead is a set of doses he has arrived at through his own clinical experience with cancer coaching clients, informed by the preclinical research and by how individual patients respond, adjusted patient by patient. He says plainly that this is exactly where human trials are needed, and that the lack of them is a genuine gap in the field of repurposed-drug oncology.

Ivermectin dosing

The starting dose he describes for most intermediate- to high-grade cancers is 1 mg/kg/day — roughly five times the dose used for treating a parasitic infection or the COVID-19 protocols that first popularized the drug. For a 60 kg adult, that works out to about 60 mg of ivermectin a day, taken seven days a week.

For lower-grade, slower-moving cancers — chronic lymphocytic leukemia that has been stable for years, or smoldering multiple myeloma — he starts lower, at 0.5 mg/kg/day (around 30 mg for a 60 kg person), closer to a standard antiparasitic dose.

In more aggressive cases, under close supervision, the dose can go as high as 2 mg/kg/day. He reports success at this higher tier — including a pancreatic cancer patient he says cleared his cancer over a few months at this dose — but flags a real cost: at 2 mg/kg, especially in elderly patients, confusion and unsteadiness on the feet become more likely. Ivermectin has a half-life of about 18 hours, so side effects generally clear within two days of stopping.

He also describes a curious feature of the dose-response relationship: it does not scale predictably. He has seen two prostate cancer patients respond very differently — one to as little as 12 mg/day, another needing 60 mg/day to see the same effect — a variability he attributes to differences between individual cancer cell populations rather than patient body weight alone. He is candid that this makes dosing "tricky," and that it is exactly the kind of variable a real dose-finding trial exists to characterize, which this field has not had.

Reassessment window

He designs his protocols around a 3-month trial period specifically so there is time for imaging to catch up to the biology — a marker can move in a month, but a scan showing a smaller lymph node takes longer to materialize.

Fenbendazole and mebendazole dosing

The standard dose he uses for either drug is 1,000 mg/day, split into two 500 mg doses. Here the published record and his own practice diverge slightly on schedule: the Stanford University Medical Center case series that documented three patients clearing stage IV cancer used a 3 days on, 4 days off cycle. He personally uses a more aggressive 6 days on, 1 day off schedule, with the day off intended to give the liver a rest.

For lower-grade or early-stage disease — he mentions early-stage prostate cancer patients who want to avoid surgery and radiation — he'll use a lower dose of 500 mg/day of either drug. The reassessment cadence mirrors ivermectin's: a 3-month trial, markers checked early, imaging follow-up at the 2–3 month mark alongside whatever surveillance imaging the patient's oncologist has already scheduled.

Choosing between mebendazole and fenbendazole

The two drugs are close to interchangeable in the preclinical literature at higher doses, but he leans toward mebendazole in specific situations: brain tumors and brain metastases, because of its better blood-brain-barrier penetration; and ovarian cancer, squamous cell carcinomas, breast cancer, and sarcomas, where the supporting research is stronger and where fenbendazole's solubility problems have limited how well it performs once it leaves the test tube.

Reported side effects

• Ivermectin, transient visual symptoms. New users at the higher doses sometimes report seeing colors more vividly, or brief visual disturbances like seeing stars — described as similar to the lightheadedness of standing up too fast. These typically resolve within one to two weeks as the body adjusts, even at an unchanged dose.
• Ivermectin, drug interactions. He flags warfarin and certain antipsychotic medications as known interactions. He reports no documented interaction with hormone therapies used in breast or prostate cancer.
• Fenbendazole/mebendazole, liver enzymes. He sees transient elevation of liver function tests in under 3% of patients. In his account, stopping the drug for a few weeks reliably brings the levels back to normal, consistent with what he describes as published reports of a reversible, transient liver irritation rather than lasting damage.

An adjunct, not a mechanism: vitamin D

Separate from the drugs themselves, he emphasizes vitamin D status — citing the same association he saw during COVID-19, where patients with poor outcomes tended to be vitamin D deficient, and pointing to evidence that adequate vitamin D levels are associated with better outcomes in cancer generally. He recommends patients get their levels checked and, if deficient, supplement with at least 10,000 IU/day. He also notes, with some frustration, that oncologists rarely order the test in the first place.

The honesty problem this creates

One dynamic he describes complicates all of the above: most of his patients do not tell their oncologist they are taking these drugs, for fear of being dropped as a patient — something he says happens more often outside the United States. The practical effect is that the oncologists best positioned to observe and document these outcomes systematically are often the ones least aware they are happening. That silence is also why none of the dosing above should be read as validated — it is one clinician's accumulated case-by-case experience, not data collected under conditions designed to separate a real drug effect from everything else going on in a patient's treatment at the same time.