Research shows that Fenbendazole, the active ingredient in a canine deworming drug Panacur, can block cancer cell metabolism, sugar uptake and cause apoptosis in cancer cells; it can reduce tumour size, lower stemness and help reduce chemo-resistance, making it another 'repurposed drug' that might be used to treat cancer.
Fenbendazole as an anti-cancer drug
The World Health Organisation has not approved this drug as a treatment for cancer. Nor is the drug approved by the FDA for human use.
This review on Fenbendazole (FBZ) highlights research studies on several cancers, the dose one might take, what other supplements might help performance, bioavailability, the frequency of usage, the side-effects and how to take it; in fact everything you need to know about Fenbendazole as a human anti-cancer drug. (Updated four times from an article by Chris Woollams, originally in 2016).
When you search Fenbendazole and cancer you will see articles almost 'shouting' that there's no evidence that Fenbendazole can treat cancer, and others 'shouting' that Fenbendazole beat yet another cancer yesterday!
Why the confusion and controversy? First, FBZ is not approved for human use. Secondly, there are no phase III Clinical Trials. Thirdly, Big Pharma does not like off-label drugs taking revenue from their cancer drugs, so it will always be called a dog or horse dewormer!
But there is another reason. Many of the people talking about this positively are not cancer scientists and are often little more than quacks. Be careful.
Fenbendazole is a benzimidazole; many cancer drugs actually have benzimidazoles at their core e.g. Abemaciclib for breast cancer, Bendamustine for lymphoma, CLL and myeloma, and PARP inhibitor Veliparib.
Other anthelmintic, or anthelminthic, benzimidazoles include Mebendazole, Oxfendazole (a metabolite of Fenbendazole), Albendazole, and Parbendazole. Indeed all have research against cancer; for example, you can read more about Mebendazole as an anti-cancer drug here.
Anthelmintics are used effectively to kill worms such as roundworms, hookworms, whipworms and some tapeworms as well as parasites. Parasitic worms are known as helminths and these drugs are also known as anthelmintic drugs. Fenbendazole is included in brands with names like Panacur and Safe-Guard.
Furthermore, the benzimidazole 'core' is found in a much wider variety of drugs beyond anti-cancer drugs. The list includes antimicrobials, antivirals, anti-parasites, anticancer, anti-inflammatory, antioxidants, proton pump inhibitors, antihypertensives, anticoagulants, immuno-modulators, hormone modulators and CNS stimulants.
The 'Accidental' discovery of anti-cancer Fenbendazole
Back in 2014, a team of researchers at top American Hospital Johns Hopkins was trying to grow tumours by injection in laboratory mice. Except with one group of mice, they failed. The reason they discovered, was that these mice had been de-wormed with an anti-parasitic drug. They read more about the drug (1), only to find that anti-cancer activity had previously been reported for Fenbendazole (writes Gilly Bertram).
The anti-cancer action of Fenbendazole
Two things are worth saying up front.
Firstly, if you cannot find research on this page for your particular cancer with Fenbendazole, it is worth checking our Mebendazole page as the two drugs both work in very similar ways. Mebendazole (MBZ) has research with brain cancer, pancreatic cancer, breast and Triple Negative Breast cancer, sarcoma and colon cancer, for example.
What's the difference between MBZ and FBZ? The first has an extra suphur molecule.
Secondly, FBZ research suggests that this drug, when used off-label, has probably at least twelve different anti-cancer actions
In particular, it inhibits tumour growth by inducing apoptosis (cell death) of tumour cells. Researchers are also finding that Fenbendazole could be useful for overcoming drug resistance which is a common setback in conventional cancer therapies.
In a 2018 paper published in Nature (2), the authors report that Fenbendazole acts as a destabilising agent on tubulin which is found in microtubules, important structural proteins making up the cytoskeleton of cells. These proteins allow the microscopic organs inside our cells (called organelles) to move throughout the cell. They also control cellular metabolism. Damaging the tubulin, damages the microtubules and this damages the cell metabolism.
These microtubules are present in worms, and also in cancer cells. The researchers conclude that there is evidence of cancer cell death by the modulation of multiple cellular pathways, which may lead to the effective elimination of cancer cells. In particularly Fenbendazole seems to work best in cancers that are p53 wild type (not mutated), as it has significant mitochondrial action.
Theoretically, Fenbendazole should be able to attack any and every cancer cell using tubulin in microtubules. And that's pretty much every cancer.
Also in the 2018 Nature research, Fenbendazole showed an affinity for mammalian tubulin and exerted cytotoxicity to human cancer cells at micromolar concentrations.
A further anti-cancer mechanism the researchers found with Fenbendazole was that after the consumption of food, it blocked the uptake of glucose in cancer cells by affecting p53, GLUT transporters and hexokinase, thus depriving cancer cells of their primary fuel. This discovery would support the use of Fenbendazole as an complementary therapy to chemotherapy and radiotherapy, as well as metabolic therapies, and potentially as a stand alone therapy.
In the various studies below, Fenbendazole also triggers apoptosis through mitochondrial injury and the caspase 3-PARP pathway. In wild-type CRC, Fenbendazole activates p53-mediated apoptosis by increasing p53 expression. Additionally, it induces necrosis, autophagy, and ferroptosis. In 5-FU-resistant CRC, Fenbendazole triggers apoptosis without affecting p53 expression, likely enhancing p53-independent ferroptosis-augmented apoptosis. Fenbendazole also causes oxidative stress and activates the MEK3/6-p38MAPK pathway, inhibiting cancer cell proliferation and enhancing apoptosis.
Put simply, Fenbendazole is attacking and killing the mitochondria in cancer cells. I'm often asked about its conflict with Niclosamide. The latter off-label drug is trying to restore the health of mitochondria, where damage has caused cancer. In other words, the two drugs operate in opposite ways.
Finally, Fenbendazole acts as a significant cancer proteasome inhibitor (3). Proteasomes are involved in a degradation pathway which is essential for many cellular processes, including the cell cycle, the regulation of gene expression, and responses to oxidative stress.
The use of anthelminthic drugs with cancer and some research behind it
It's not just the 2018 Nature paper that has demonstrated the effective use of Fenbendazole and others for various types of cancer cells -
* Non-small Cell Lung Cancer (3),
* Lymphoma - In this study using mice (4), an even better result was obtained when using supplements B, D, K, E, and A. as well as the FenBen. In a new 2024 study with NHL, the addition of Fenbendazole to CHOP chemotherapy had a significant cancer reduction effect in patients (12).
* Prostate cancer - An early study showed Fenbendazole effective with metastatic prostate cancer; A further study showed prostate cancer cells were killed where Fenbendazole was used together with vitamin E succinate (5). And a 2024 study showed Mebendazole could be a 'game changer' when used with Docetaxel by a team at Glasgow University (6).
* Glioblastoma, or GBM, has several studies with Mebendazole, MBZ (7).
* Bladder cancer, kidney cancer - In 2021 a group at Stanford University Medical Center, Department of Medicine, published a Case Series (Clin. Oncol. Case Rep 2021) with patients having either cancer at Stage 4 level using repurposed drug Fenbendazole and eradicating their cancer after 3 months (8).
* Colorectal cancer - In the early 90s, another antihelmintic drug called Levamizole was shown as a effective complementary treatment for colon cancer (CRC) and was shown to restore a depressed immune system (9). In 2022, Fenbendazole was shown to be effective in 5-FU resistant colorectal cancer (10). And we have recorded 2023 in vivo research on the Mebendazole page where the anti-helminthic strongly and selectively inhibited colorectal cancer proliferation, reduced tumour size and induced apoptosis.
* Triple Negative Breast Cancer - on the Mebendazole page we reported an in vivo study with mice showing that two benzimidazoles along with butyrate and proprionate (two short chain fatty acids made by gut bacteria), extended survival times with superior cytotoxic effects.
FBZ exhibits multiple action on cancer pathways -
The multiple actions are primarily through microtubule destabilisation, glycolysis inhibition, and p53.
Microtubule Destabilisation: Fenbendazole acts as a moderate microtubule-destabilising agent, disrupting mitotic spindle formation and causing G2/M phase cell cycle arrest, leading to mitotic catastrophe and apoptosis. This mechanism is similar to that of vinca alkaloids and is observed in colorectal, ovarian, and lung cancer cells.
Glycolysis Inhibition: It downregulates GLUT1 transporters and hexokinase II (HKII), key enzymes in cancer cell glucose metabolism. This reduces glucose uptake and lactate production, starving cancer cells of energy and disrupting the tumor microenvironment. This effect is linked to p53-mediated inhibition of glycolytic pathways.
p53 trabslocation: Fenbendazole induces p53 translocation into mitochondria, enhancing p53 expression and activating the p53-p21 pathway, which triggers apoptosis and cell cycle arrest in cancer cells.
Apoptosis and Cell Death: It promotes cancer cell apoptosis via caspase-3-PARP activation, mitochondrial injury, and caspase-8-dependent pathways. In p53-mutant or resistant cells, FBZ induces p53-independent apoptosis augmented by ferroptosis (via GPX4 and SLC7A11 suppression).
Other Pathways: It activates the MEK3/6-p38MAPK pathway, increases ROS production, and inhibits proteasomal function, contributing to cytotoxicity. Transcriptome analysis in ovarian cancer shows significant enrichment in mitosis, cell cycle, and DNA replication pathways.
Fenbendazole anti-cancer protocol - amounts and support compounds
Perhaps the most famous anecdotal evidence comes from cancer patient, Joe Tippens, an avid researcher who was given three months to live, who decided to try Panacur with the agreement of his consultant . There's a review in Anti-cancer research 2024 (11). Joe took a combination of nutrients to support FBZ, while deciding not to change his diet with his NSCLC. It worked!
Joe Tippens' original protocol for Fenbendazole with lung cancer consits of:
- 1 gram granules of canine drug ‘Panacur C’, these contain 222mg of Fenbendazole; taken 3 days on, 4 days off
- Vitamin E Succinate (800IU daily)
- Bioavailable Curcumin (600mg daily)
- CBD oil (25mg per day)
From our anti-cancer experience, we would suggest patients use ''total' complete vitamin E with all 4 tocopherols and all 4 tocotrienols, instead of the succinate version.
We suggest patients add both Berberine (3 x 500 mg) and Quercetin (2 x 500 mg) to enhance the anti-cancer, sugar reducing and antiinflammatory effects. And take magnesium glycinate - women 350 mg; men 450 mg .
As you will see below, we have links to an article reviewing the off label drug, Ivermectin (an insecticide) alongside anthelmintic drugs. Ivermectin is gaining a lot of attention in combination with Fenbendazole against cancer and Chris Woollams first wrote about this combination in 2020..
In a protocol from 5 doctors at the Stanford School of Medicine (8), all patients had chemo for their cancers; the additional FBZ protocol was typically 1000 mg Fenbendazole 3 days per week; vitamin E daily 800 mg; Curcumin, 600 mg; CBD oil. All patients became NED (No evidence of disease).
Fenbendazole toxicity, bioavailability, side-effects and safety in humans
Although the original clinical approval for Fenbendazole was for intestinal parasites and not for cancer, and it is approved for animal use, the drug had already gone through human clinical trials and so all of the clinical trial work related to toxicity has already been done and Fenbendazole has been deemed safe for human consumption for many years.
Side effects? It can cause diarrhoea, stomach pain, rashes, and a swollen stomach. And at high doses it may cause liver toxicity, so you should monitor your liver enzymes.
The label for the product approval talks of animals not humans. With animals, it is known that there is a likely interaction with salicylanilides like Niclosamide and Dibromsalan, and we suggest you avoid mixing it with either.
Dose: If you want the Truth, no body knows. There's absolutely no research that tells you exactly how much to take. And there's no research on doses when combining it with Mebendazole and/or Ivermectin. As a result, we start at the low level of 222 mg, and increase it rapidly while monitoring liver enzymes.
Many people take FBZ 3 days on 4 off like Joe Tippens did; Care Oncology used MBZ one month on, one off. Others want to take it every day, others want higher doses. We have a lady in Australia with Endometrial cancer AND thyroid cancer taking 2 gm a day, every day since she was told she had just 3 months to live. That was over three years ago.
FBZ has poor water solubility and low oral bioavailability, meaning it may not reach effective systemic levels in the body if you take it on its own with water. We suggest it is always taken with meals containing fat.
We have a defined protocol, putting safety first.
Warning: If you are thinking of taking Fenbendazole, we suggest you talk to Chris Woollams first on chrismeanshealth@gmail.com.
***** The 3-in-1 anti-cancer Protocol - Ivermectin, Mebendazole and Fenbendazole
Chris Woollams writes, "I am increasingly asked about combining Ivermectin with either or both anthelmintic drugs Fenbendazole and Mebendazole. This question is quite popular in younger people with Turbo cancer, and especially in older patients with recurrent Prostate cancer, Colorectal cancer and Lung cancer where the existing drugs offer little hope.
I have written a Blog specifically on this subject. You can read it HERE. I call it the '3-in-one protocol' using Fenbendazole, Mebendazole and Ivermectin. I provide details links and doses and there is even recent research to support this protocol which deals with the mitochondrial stem cell connection".
You can contact Chris on chrismeanshealth@gmail.com to ask about building you an off-label drug protocol as a part of his normal Personal Prescription plan.
Readers also read these pages
Go to: Repurposed drugs as cancer treatments
Go to: Personal Prescriptions with Chris Woollams
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References
- Surprise Finding Yields a Possible Tumor-Fighting Drug; Johns Hopkins Medicine
- Fenbendazole acts as a moderate microtubule destabilizing agent and causes cancer cell death by modulating multiple cellular pathways; https://www.nature.com/articles/s41598-018-30158-6
- Impairment of the Ubiquitin-Proteasome Pathway by Methyl N-(6-Phenylsulfanyl-1H-benzimidazol-2-yl)carbamate Leads to a Potent Cytotoxic Effect in Tumor Cells ; https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3436308/
- Unexpected Antitumorigenic Effect of Fenbendazole when Combined with Supplementary Vitamins; https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2687140/
- Effects of fenbendazole and vitamin E succinate on the growth and survival of prostate cancer cells' - December 2011Journal of Cancer Research and Experimental Oncology 3(9)
- Repurposing screen identifies mebendazole as a clinical candidate to synergise with docetaxel for prostate cancer treatment; Linda K Rushworth et al; 2024, University of Glasgow; http://eprints.gla.ac.uk/207115/
- Antiparasitic mebendazole shows survival benefit in 2 preclinical models of glioblastoma multiforme; https://www.ncbi.nlm.nih.gov/pubmed/21764822
- The Medical Adviser - FENBENDAZOLE in Stage 4 Cancers - the 2021 Stanford University Case Series
- Levamisole in the adjuvant treatment of colon cancer;https://www.ncbi.nlm.nih.gov/pubmed/2009737
- Anti-cancer effects of fenbendazole on 5-fluorouracil-resistant colorectal cancer cells; Deokbae Park, Jung-Hee Lee, Sang-Pil Yoon, Korean J Physiol Pharmacol. 2022 Sep 1;26(5):377–387.
- Oral Fenbendazole for Cancer Therapy in Humans and Animals; JOLIE NGUYEN, THAI Q. NGUYEN, BO HAN and BA X. Anticancer Research September 2024, 44 (9) 3725-3735;
- Fenbendazole Exhibits Differential Anticancer Effects In Vitro and In Vivo in Models of Mouse Lymphoma; Haebeen Jung, Si-Yeon Kim, Hong Gu-Joo; Current Issue Mol Biol 2023 45 (11), 8925
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