Mebendazole is an inexpensive medicine for intestinal worms that has been used in people since the 1970s. Of all the antiparasitic drugs now discussed for cancer, it has gone furthest in human research: it has been tested in early-phase trials, in one randomized trial that reported a benefit, and in one small trial that did not. This article explains how mebendazole acts on cancer cells, what each of those trials found, what the newest 2026 research adds, and what is known about its safety.
What Mebendazole Is
Mebendazole belongs to the benzimidazole family, the same family as the veterinary drug fenbendazole and the human drug albendazole. Unlike fenbendazole, mebendazole is an approved human medicine, manufactured to pharmaceutical standards, with decades of safety data. It is poorly absorbed from the gut, which is ideal for treating worms but is a challenge for treating cancer, because only a small fraction of each dose reaches the bloodstream.
How Mebendazole Acts on Cancer Cells
A 2014 review by the Repurposing Drugs in Oncology project, a European collaboration, gathered the laboratory and animal evidence and concluded that mebendazole acts on cancer through several independent routes.1
1. It disrupts cell division
Like the rest of its family, mebendazole binds tubulin, the protein that builds the microtubules a cell needs to divide. Dividing cancer cells stall and die.1
2. It reaches the brain
Most cancer drugs cannot cross the blood–brain barrier. Researchers at Johns Hopkins found that mebendazole does, and that it extended survival in two mouse models of glioblastoma, the most aggressive brain cancer.2 This is why so much of the human research on mebendazole has been in brain tumors.
3. It blocks the Hedgehog pathway
The Hedgehog pathway is a developmental growth signal that some cancers switch back on, including medulloblastoma and basal cell carcinoma. Mebendazole suppressed Hedgehog signaling and slowed medulloblastoma growth in laboratory models.3
4. It activates immune cells (research from Sweden)
Researchers at Uppsala University found that mebendazole pushed monocytes and macrophages toward the M1 state, the form of these immune cells that attacks tumors, rather than the M2 state that helps tumors grow.4
5. It cuts both of the cancer’s main fuels (2026)
Many cancers run on two fuels: glucose and the amino acid glutamine. A June 2026 study from Boston College tested mebendazole in young mice with high-grade glioma. Mebendazole reduced markers of both glucose and glutamine metabolism, and it worked best when the mice were also on a ketogenic diet, which lowers the glucose supply. The combination reduced tumor invasion and improved survival.5 This is animal research, but it fits a larger body of work suggesting that metabolic drugs and metabolic diet work better together than either alone.
How Far Mebendazole Has Been Studied in People
The randomized trial in colorectal cancer (Egypt)
The most important human study is a randomized trial from Tanta University in Egypt. Forty patients with metastatic colorectal cancer received standard FOLFOX chemotherapy with bevacizumab, and half were randomly assigned to receive mebendazole as well. The mebendazole group had better tumor response and longer progression-free survival than the group on standard treatment alone.6 This is genuinely positive randomized evidence. It is also a single small trial that has not yet been repeated, so it is a strong signal rather than proof.
The brain tumor trial (Johns Hopkins)
In a phase 1 trial at Johns Hopkins, adults with newly diagnosed high-grade glioma received mebendazole together with standard temozolomide chemotherapy. The trial was designed to find a safe dose. High doses were tolerated, and the main limit was a rise in liver enzymes that reversed when the dose was lowered.7 Because every patient received mebendazole, the trial could not show whether it improved survival. Further brain tumor trials in children and adults have followed.
The gastrointestinal trial (Sweden)
The same Uppsala group ran a small phase 2a trial of mebendazole on its own in patients with advanced gastrointestinal cancers who had exhausted other treatments, adjusting each patient’s dose to their blood levels. Mebendazole was well tolerated, but the tumors did not shrink, and the trial was stopped early.8 Together with the Egyptian results, this suggests mebendazole is more likely to help as a partner to other treatment than as a treatment by itself.
Individual case reports
Two published case reports describe striking responses to mebendazole alone: a patient in Sweden with metastatic colon cancer whose lung and lymph node metastases almost completely disappeared,9 and a patient in the United States with metastatic adrenocortical carcinoma whose disease was controlled for an extended period.10 Case reports show what is possible in an individual, not what to expect.
A retracted 2026 study
A June 2026 study in Anticancer Research reporting high benefit rates in 197 patients taking ivermectin with mebendazole was retracted in October 2026 for methodological and analytical problems. It should not be used as evidence. Our ivermectin and cancer article explains what happened.
Known Side Effects and Drug Interactions
Liver enzymes. At the high doses studied in cancer, the main side effect is a rise in liver enzymes, which in the Johns Hopkins trial reversed when the dose was reduced.7
Blood counts. Prolonged high-dose use has been associated with low white blood cell counts, so blood counts are monitored during long courses.
A dangerous combination with metronidazole. Taking mebendazole together with the antibiotic metronidazole has been linked to rare but severe skin reactions (Stevens–Johnson syndrome and toxic epidermal necrolysis). The two should not be combined.
Other interactions. Cimetidine can raise mebendazole levels. Seizure medicines such as carbamazepine and phenytoin speed its breakdown and lower its levels, which matters for brain tumor patients who often take them.
Pregnancy. Mebendazole is avoided in pregnancy.
Where Mebendazole Fits in an Integrative Approach
The pattern across the human studies is consistent: mebendazole looks most promising alongside other treatment rather than alone. Its actions on microtubules, blood vessel growth, the Hedgehog pathway, immune cells and cancer metabolism give it several distinct ways to add to a plan, and its ability to reach the brain makes it unusual among repurposed drugs. The 2026 Boston College work adds a metabolic reason to pair it with a ketogenic diet.
Chemosensitivity testing can include mebendazole and show directly whether a patient’s own cancer cells respond to it. For how mebendazole compares with its veterinary relative, see our article on fenbendazole and cancer. Our book, The New Reality of Cancer, organizes repurposed drugs by the cancer pathways they act on.
Frequently Asked Questions
Has mebendazole been tested in cancer patients?
Yes. It has been tested in early-phase brain tumor trials, a small randomized trial in metastatic colorectal cancer that reported benefit, and a small gastrointestinal cancer trial that did not.
Is mebendazole better than fenbendazole?
Mebendazole has a far stronger human record: it is an approved human medicine and has been tested in clinical trials. Fenbendazole is an animal medicine with no completed human cancer trials.
Does mebendazole cross into the brain?
Yes. Animal studies show it reaches brain tissue, which is why it has been studied in glioma and medulloblastoma.
What should mebendazole never be combined with?
Metronidazole. The combination has been linked to severe skin reactions.
About the author. Dr. Silver, MD, graduated from Temple University School of Medicine, trained as an interventional cardiologist, and has practiced medicine for nearly fifty years. A lymphoma survivor of about twenty-five years, he is co-author, with Dr. Lindmeier, DHSc, of The New Reality of Cancer: The Science of Recovery. Read more about Dr. Silver, MD.
Research by Dr. Lindmeier, DHSc, cancer educator and co-author of The New Reality of Cancer.
More articles on repurposed drugs for cancer and all articles.
References
- Pantziarka P, Bouche G, Meheus L, Sukhatme V, Sukhatme VP. Repurposing Drugs in Oncology (ReDO)—mebendazole as an anti-cancer agent. ecancermedicalscience. 2014;8:443.
- Bai RY, Staedtke V, Aprhys CM, Gallia GL, Riggins GJ. Antiparasitic mebendazole shows survival benefit in 2 preclinical models of glioblastoma multiforme. Neuro-Oncology. 2011;13(9):974–982.
- Larsen AR, Bai RY, Chung JH, et al. Repurposing the antihelmintic mebendazole as a hedgehog inhibitor. Molecular Cancer Therapeutics. 2015;14(1):3–13.
- Blom K, Senkowski W, Jarvius M, et al. The anticancer effect of mebendazole may be due to M1 monocyte/macrophage activation via ERK1/2 and TLR8-dependent inflammasome activation. Immunopharmacology and Immunotoxicology. 2017;39(4):199–210.
- Ketogenic diet as a metabolic vehicle enhancing the therapeutic efficacy of mebendazole and devimistat in juvenile syngeneic high-grade glioma. Boston College. Published 16 June 2026.
- Hegazy SK, El-Azab GA, Zakaria F, Mostafa MF, El-Ghoneimy RA. Mebendazole; from an anti-parasitic drug to a promising candidate for drug repurposing in colorectal cancer. Life Sciences. 2022;299:120536. doi:10.1016/j.lfs.2022.120536. ClinicalTrials.gov NCT03925662.
- Gallia GL, Holdhoff M, Brem H, et al. Mebendazole and temozolomide in patients with newly diagnosed high-grade gliomas: results of a phase 1 clinical trial. Neuro-Oncology Advances. 2021;3(1):vdaa154.
- Mansoori S, Fryknäs M, Alvfors C, Loskog A, Larsson R, Nygren P. A phase 2a clinical study on the safety and efficacy of individualized dosed mebendazole in patients with advanced gastrointestinal cancer. Scientific Reports. 2021;11:8981.
- Nygren P, Larsson R. Drug repositioning from bench to bedside: tumour remission by the antihelmintic drug mebendazole in refractory metastatic colon cancer. Acta Oncologica. 2014;53(3):427–428.
- Dobrosotskaya IY, Hammer GD, Schteingart DE, Maturen KE, Worden FP. Mebendazole monotherapy and long-term disease control in metastatic adrenocortical carcinoma. Endocrine Practice. 2011;17(3):e59–e62.
This article is for education only. It is not medical advice and does not diagnose or treat any condition. Cancer Expert MD has no financial relationship with any laboratory, drug maker, supplement company, clinic or hospital.
Responses
[…] Many cancers also run on glutamine, an amino acid the body makes in its own muscles, so diet alone cannot restrict it. Some cancers run largely on fat. A plan built on the Warburg effect therefore has to consider all three fuels. Blocking glutamine is being studied with drugs, and a June 2026 study from Boston College found that the repurposed drug mebendazole reduced both glucose and glutamine use in brain tumors in mice. Read more in our article on mebendazole and cancer. […]
[…] a Boston College study found that a ketogenic diet strengthened the effect of the repurposed drug mebendazole against brain tumors in […]
[…] An approved antiparasitic medicine that disrupts cell division and reaches the brain. A small randomized trial in Egypt found better response and longer progression-free survival when mebendazole was added to chemotherapy for metastatic colorectal cancer, while a Swedish trial of mebendazole alone did not shrink tumors. Read our full article on mebendazole and cancer. […]