Evidence Explorer · MS-N280 · Investigational drug repurposing · Appraised November 9, 2026
Mebendazole has anticancer activity in laboratory models, but human results are inconsistent and do not establish it as cancer treatment. A small gastrointestinal-cancer study stopped for rapid progression, a recurrent-glioblastoma trial missed its prespecified benchmark, and a widely circulated ivermectin–mebendazole cohort was retracted.
Evidence at a glance
- Populations: recurrent glioblastoma, refractory gastrointestinal cancers, newly diagnosed high-grade glioma and a small metastatic-colorectal trial.
- Studied regimens ranged from individualized dosing up to 4 g/day to 800–1,600 mg three times daily with chemotherapy—far beyond routine short-course antiparasitic use.
- Results: 10 treated gastrointestinal-cancer patients all progressed; randomized recurrent-glioblastoma arms failed the prespecified 55% nine-month survival benchmark. A 40-person colorectal report was positive but small, retrospectively registered and not independently replicated.
- Evidence label: mixed, low-certainty investigational evidence; no established cancer-control benefit.
What was studied
The RepoMeb phase 2a study enrolled 11 people with refractory gastrointestinal cancer; 10 started treatment and all stopped because of progression. Four met proposed hyperprogression criteria, though the uncontrolled design cannot prove causation.
In recurrent glioblastoma, 88 participants were randomized between mebendazole plus temozolomide or mebendazole plus lomustine. Nine-month survival was 36.6% and 45%, respectively—below the study’s 55% benchmark—and no arm omitted mebendazole, so its contribution cannot be isolated.
A 40-person metastatic-colorectal report described a large response and progression-free-survival difference when mebendazole was added to FOLFOX4/bevacizumab. Its registry remains outdated, carries no posted results and was last verified in 2019; the finding needs independent prospective replication.
What this evidence cannot establish
Cell and animal activity does not establish effective human tumor exposure. Phase I tolerability cannot prove efficacy, and a retracted self-reported ivermectin–mebendazole cohort must not be used to support treatment claims.
Safety and practical context
High oncology doses have produced liver-enzyme elevations and can suppress bone marrow. Trials also report gastrointestinal symptoms, electrolyte abnormalities and treatment discontinuations.
Over-the-counter antiparasitic dosing is not interchangeable with oncology research dosing. Self-treatment can confound liver injury, blood-count abnormalities and assessment of the cancer itself.
Questions for the care team
- Is the proposed use part of a registered, monitored clinical trial?
- What human comparison supports benefit for my cancer type?
- How will liver tests, blood counts and interactions with chemotherapy be monitored?
Sources and identifiers
- RepoMeb gastrointestinal-cancer phase 2a study — PMID 33903692
- Randomized recurrent-glioblastoma phase II trial — PMID 35747192
- Small metastatic-colorectal randomized report — PMID 35385794
- Colorectal study registry record — NCT03925662
- High-grade-glioma phase I study — PMID 33506200
- Retraction notice for the ivermectin–mebendazole cohort — PMID 42823188
Funding and conflicts: The cited studies include academic, public and charitable support. Funding and conflicts differ by trial; the retracted cohort involved authors affiliated with a commercial telemedicine/wellness organization.
Source access and dates: Original reports, registry records and official safety sources available through the links above were checked November 9, 2026. Last literature search November 9, 2026.
Educational evidence summary, not individualized medical advice. Investigational or repurposed products should not replace established cancer treatment. Symptom, biomarker, laboratory or animal findings do not establish tumor control, recurrence prevention or longer survival.
