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Fenbendazole was originally designed to cure parasites by selectively blocking the synthesis of microtubules by binding to β-tubulin. This stops the polymerization of tubulin dimers in cells of parasites and causes parasite death.

Surprisingly, it seems that fenbendazole as well as other benzimidazoles exhibit a similar effect against tumor cells. Today it is thought that there are 3 main mechanisms in which fenbendazole kills cancer:

1) Apoptosis induction. The anti-tumor effect is believed to be through the interaction of the drug with the β-tubulin leading to cell cycle arrest and cytotoxic.

Inhibition of polymerization of tubulin into microtubules by benzimidazole carbamates in both helminths and human tumor cells is well documented. (Source1, Source2)

2) Inhibition of glucose uptake in cancer cells. Malignant cells are known to have an enormous glucose uptake. Cancer cells normally consume glucose 200 times faster than ordinary cells due to aerobic glycolysis (Warburg effect). This can be seen in PET scans – the metabolically active sites, which use more radioactive glucose can be clearly seen and are generally thought to be cancerous tumors or sites of inflammation.

Fenbendazole limits cancer cell fueling with sugar by limiting the glucose uptake, decreasing the amount of GLUT transporters (canals that take glucose into the cancer cells from the blood) and the enzyme hexokinase 2. The latter is important for cancer cell survival, it helps the tumors thrive by generating more sugar and accelerating lactic acidosis in the extracellular matrix. (Source1, Source2

3) Reactivation of the p53 gene. This work mechanism is still relatively controversial, and more studies need to be done to confirm that fenben causes this action. (Source)

However, there is an increasing number of studies that confirm the fact that fenbendazole might truly increase the strongest tumor suppressor in our bodies – p53. (Source)

It is known that elephants have 20 copies of the p53 gene in their genome and humans have only 1 copy. Interestingly, that is why elephants get cancer less frequently than us, humans. Despite these creatures having a huge body size, a larger number of cells and a bigger number of potential genetic mutations.

Additional characteristics that make fenbendazole a remarkable anti-cancer strategy.

Cancer cells don’t develop resistance to fenbendazole.
What’s interesting, cancer cells cannot evade this de-wormer drug and adapt to its presence. This means that it can be taken constantly and remain effective. Unfortunately, advanced cancer can develop chemo-resistance to many chemotherapy and biological therapy medications, making them ineffective in time.

One of the main mechanisms of chemo-resistance in cancer cells is the adaptation of excreting the anti-cancer drugs to the outside via special drug efflux pumps called P-glycoproteins. Fenbendazole is not a target for p-glycoproteins, so it cannot be excreted out of cancer cells once it gets inside.

Therefore, the tumors don’t develop resistance against fenbendazole. It will still remain effective and kill cancer cells, which does not seem to be the case with a lot of chemotherapy drugs once chemo-resistance is developed. (Source)

Fenbendazole could sensitize tumors to radiotherapy.
The dog-dewormer could be a considerable option before and during radiation treatment. It sensitizes the cancer cells to the treatment in a similar way like chemotherapy agents from the taxane group. (Source)

This Post Has 17 Comments

  1. Susie

    Some of the referenced papers on albendazole testing in mice with peritoneal implants concluded that intra-peritoneal treatment was very effective, whereas oral administration was not. This is interesting to me as I have peritoneal tumors. Are you aware of any clinics, alternative or otherwise, that can administer antithelmics intraperitoneally?

    1. fenbendazole

      Dear Susie,
      The effectiveness of intraperitoneal albendazole in treating peritoneal tumors, as demonstrated in mouse studies, is indeed significant. However, finding clinics that offer this specific treatment can be challenging since intraperitoneal administration of anthelmintics like albendazole is not a common practice and is often considered experimental.
      Currently, there are no widely accepted clinical guidelines or practices for the intraperitoneal administration of fenbendazole in humans. Nevertheless, ongoing research and emerging scientific evidence indicate that fenbendazole might be a promising candidate for cancer treatment, including peritoneal tumors.
      While we recommend taking fenbendazole orally in the standard manner, the choice of how you administer the medication ultimately rests with you.

  2. Bardo Wesselius


    I recently had a whipple surgery to remove a pancreas carcinoma. Before that I had 8 chemo cycles, and from the start I also used fenbendazol as addition to the chemo therapy. It seems to have worked, the tumor had shrunk so the surgery was succesfull. Since fenbendazol interacts with cell cycles, how long after the surgery can I take fenbendazol again? In about 3 weeks I will have chemo therapy again, the last four sessions. Greetings from the Netherlands.

    1. fenbendazole

      Hello, Bardo, thank you for your comment and the great question!
      You may wait at least a week – week and a half. Then if you feel okay, you may continue protocol. Also please keep in mind, that fenbendazole therapy and chemotherapy work best together if you make pauses with fenben at least 2 days prior and 2 days after a chemo round. This is because chemotherapy is particularly effective against quickly multiplying cells, although fenbendazole  also inhibits cancer growth. So, if you want to achieve the optimum benefit from both therapies, we recommend taking brakes from fenbendazole before and a little after chemotherapy rounds.

  3. Thomas Neil

    I have aggressive prostate cancer.
    I am on abiraterone currently.
    Can I take Fenbendazole

    1. fenbendazole

      Hello, Thomas.
      Abiraterone is working by blocking the production of these hormones, abiraterone helps to slow down the progression of prostate cancer and may shrink tumors. It usually does not affect liver function. Still sometimes side effects of abiraterone may include fatigue, joint pain, high blood pressure, fluid retention, and LIVER FUNCTION abnormalities. So keep that in mind and make sure your liver enzymes are not too high. A blood test can show your liver enzyme results. We recommend tracking your enzymes at least every 1-2 months. It is important for individuals taking abiraterone to undergo regular monitoring of their liver function and other blood parameters to ensure the medication is well-tolerated.

  4. DC Hale

    d in the USA? Does it require a prescription? Where can fenbendazole be purchased in the USA? Does it require a prescription, or can it be purchased as a pet product?

    1. fenbendazole

      Hello, Hale thank you for a question.
      Typically, veterinary stores carry it for sale, though in limited quantities. Additionally, it is available for purchase on online shopping sites such as Amazon and at tractor supply. You may check most reputable sources in our “SUPPLIERS” section. https://www.fenbendazole.org/suppliers/

  5. danny

    i am on diaylsis and have cirrohsis of liver I have just been diagnosed with adenocarcinoma cancer is fenbendazole safe for me to take

    1. fenbendazole

      Hello, Danny. Thank you for contacting us!
      Supplements and medications used during hemodialysis are critical. In dialysis patients, the drug dosage is usually lowered by 5-6 times. So we would propose you start with 40mg a day and then watch your liver enzymes. If everything is fine, only then consider gently increasing the amount.

  6. Betty

    See under Instructions

    The treatment can be combined with the majority of chemotherapeutic drugs, radiation, or surgery.

  7. zoritoler imol

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  8. zoritoler imol

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  9. Dina

    4 months post kidney transplant and my husband has newly diagnosed stage 4 pancreatic cancer with spread to liver. How does this effect liver as oncologist stating his liver not strong enough to receive chemo?

    1. fenbendazole

      Dear Dina,
      Fenbendazole is processed in the liver, which could heighten the risk of liver-related side effects. Given your husband’s condition and the presence of cancer in his liver, it is crucial to approach Fenbendazole use with caution. Begin with doses lower than those recommended by standard protocols and gradually increase them. Simultaneously, closely monitor your husband’s health and regularly check his liver enzyme levels to ensure there are no adverse effects.

  10. George Barker


  11. Gregory Roessner

    My wife has Stage 4 pancreatic adenocarcinoma. She was scheduled for Whipple surgery, but surgeon noted metastasis to peritoneum , so removed gall bladder and closed up . Now trying to decide best course . I favor Fenbendazole therapy ; she wants more chemo. Trying to convince her to try this unconventional approach , which is no doubt .held in disdain by the Medical Establishment. Question : She must suspend all chemo , allow a time to recover and then start Fenben therapy protocol . Is this correct ? Can’t have both going at once , I assume . So , what timeframe for recovery before starting Fenben therapy ?

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