Fenbendazole Side Effects and Safety in Humans: Dosage, Risks and Precautions (2025)
Joe Tippens founded the protocol after he was told a story about a scientist at Merck Animal Health that had been performing cancer research on mice. The research included injecting different types of cancers into different mice body parts. The scientists discovered, through trial and error, a product in their canine product line, fenbendazole, that was batting 1.000 in killing these different cancers in the mice. The scientist was later diagnosed with stage 4 brain cancer and was given a grim prognosis of only three months to live. She decided to try the fenbendazole, and after six weeks, showed a clean scan.
Joe Tippens had been initially diagnosed with small cell lung cancer. The cancer later spread to his neck, right lung, stomach, liver, bladder, pancreas and tail bone. Like the scientist from Merck Animal Hospital, Joe was told he only had three months to live. In 2017, after hearing the story of the scientist who treated her cancer with a canine drug, Joe decided he was going to do the same. However, in addition to taking the fenbendazole, Joe added his own ingredients to the regimen (curcumin, CBD oil, and vitamin E), thus creating the Joe Tippens Cancer Protocol.
Disclaimer: We in no way endorse the Joe Tippens Cancer Protocol as a cure for cancer, and as always, you should consult your physician before starting any new medications or treatment plans.
Why Cancer patients use Fenbendazole
This article discusses dosage considerations and key factors regarding the use of fenbendazole in cancer treatment.
Commonly available information about fenbendazole dosages is often inaccurate when applied to potential cancer-related uses. Many sources cite standard dosages recommended for treating parasitic infections, rather than dosages studied specifically in the context of cancer research.
The anti-parasitic dosage is not as effective for people looking for a dosage against cancer. Dosage will need to be adjusted according to cancer type and stage.
Fenbendazole dosage should be based on fenbendazole cancer studies. Multiple factors are considered including studies including fenbendazole for cancer, anecdotal studies and case series, the aggressiveness of the cancer type and the cancer stage.
Cancer dosage estimation can be adjusted based on the time that a person has to beat cancer or its risk to the patient - this includes both the cancer type and whether the cancer has spread or metastasised.
Some cancers provide the patient with less time to beat the cancer e.g. fast growing cancer, and of course; metastasis also means that the time to beat the cancer is shorter than before metastasis.
Fenbendazole Side Effects in Humans
Although safety data exists for various animals, the safety and tolerability of Fenbendazole in humans for sustained periods of time have not been thoroughly studied yet. Nevertheless, many patients have decided not to wait for the lengthy bureaucratic process of scientific data to be published; they are following the protocol at their own risk. Most of these people report taking Fenbendazole without any side effects.According to a study available from the European Medicine Agency, doses up to 500 mg per person did not result in serious adverse effects. Moreover, single doses of up to 2,000 mg per person were reported to cause no serious adverse effects over the course of ten days.
According to the product description on Amazon, fenbendazole is "Safe for all Dogs 6 weeks and older, including pregnant Dogs".
Based on toxicology studies, benzimidazoles such as Fenbendazole, Mebendazole or Albendazole seem to be safe drugs.
However, a drug without any side-effects does not exist. Scientific data reports do not reveal significant adverse reactions from taking fenbendazole. Despite the fact, there are anecdotal reports of potential toxicity: Up to 5 % of people can experience stomach discomfort or diarrhea when taking large quantities of fenbendazole with no breaks.
People with severe liver or kidney failure have lower medication excretion rates, therefore, fenbendazole can accumulate and cause unexpected side-effects. Doses should be divided accordingly in this situation.
When used in large quantities for a long period of time without breaks, fenbendazole can cause an asymptomatic liver enzyme increase due to the fact of the substance being mainly metabolized in the liver. This is reversible with the help of a couple week pause from the medication.
The protocol was designed to keep the liver in optimal health, therefore
the schedule of weekly 3 days on, 4 days off was previously suggested.
However, more and more people are using fenbendazole on a daily basis
without problems.
We would still recommend taking at least 1
day off per week to avoid over-stressing the liver if the medication is
to be used for prolonged periods of time (like months or years).
To
keep the liver health optimal, we advise you to take 250 mg capsules of
Milk Thistle or 150 mg of Silymarin daily as a supportive supplement for
keeping it in great shape.
References:
- Lacey, E. (1979). Mode of action of benzimidazoles
- Blanchard, P., & Villard, J. (2008). Toxicological profile of benzimidazole derivatives: Fenbendazole and mebendazole
- Morris, G. M., & Keppler, D. (2019). The role of anthelmintic drugs in the treatment of cancer
- Lacey, E., & Morrell, A. (2013). Benzimidazoles in cancer therapy: repurposing anthelmintics for oncology
Side Effects of Fenbendazole Reported:
Most people have NO side effects. The main complaints of the small group of people who did experience side effects were:* Mild diarrhea
* Mild stomach discomfort
* Elevated liver enzymes
Who May Be At Greater Risk of Side Effects?:
- People who use Fenbendazole in high doses.
- Use of medications and supplements that use the same pathways for metabolism as Fenbendazole.
- Those taking treatments/medications that increase liver enzymes.
- One research suggests that those who are weak from chemotherapy may experience more side effects than those not receiving conventional cancer treatment, particularly in elevated liver enzymes.
Has there ever been a documented case of permanent liver injury from fenbendazole?
How Safe is Fenbendazole?
Is fenbendazole harmful to humans? Due to the long and successful use of fenbendazole as a veterinary antiparasitic medicine since the late 1950s, a wealth of safety data has been acquired that has stood the test of time. According to Drugs.com, there are no commonly used drugs that interact with fenbendazole.Fenbendazole is so safe for veterinary consumption that it is sold by the 50-lb bag! The image below is from the 2011 film Bernie. The image is striking because seeing the many bags of Safe-Guard is reassuring regarding what must be, and is the extreme safety profile of fenbendazole.
In other words, since fenbendazole is dumped into the feed of the animals with very little fretting over the exact dosage received, the standard dose of 222 mg fenbendazole (the amount used to deworm a 10-lb dog) used for cancer treatment is certainly at the lower end of any practical scale of toxicity! Also recall that the nation of India routinely deworms its population twice a year using a fenbendazole analog (albendazole).
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The image is from the 2011 film Bernie with the many bags of
Safe-Guard |
Fenbendazole Dosage for Humans
Protocol (the initial version) – complimentary treatment of cancer
- Fenbendazole 222 mg. Consume one capsule 3 days weekly, once time daily after eating a fatty dinner. * Then do not take any for 4 days. Replicate this cycle each week.
- Vitamin E 800 U/I. Consume one capsule or another form once daily after eating without any waiting.
- Bio-Available Curcumin 600 mg. Consume one capsule twice daily after eating breakfast and lunch without waiting.
- CBD oil 25 milligrams. Consume one to two drops (total ~25 milligram) under your tongue daily before bedtime.
Protocol (the altered, stronger version) – complimentary cancer treatment
- Fenbendazole 222 milligrams. Consume one capsule daily after eating a fatty dinner without waiting. **
- Vitamin E 800 U/I. Consume one capsule or some other version daily without waiting.
- Bio-Available Curcumin 600 mg. Consume one capsule twice daily after eating breakfast and lunch without waiting.
- CBD oil 25 milligrams. Consume one to two drops (total ~25 milligrams) under your tongue daily before bedtime.
Avoiding cancer relapse – prophylactic procedure
- Fenbendazole 222 milligrams. Consume one capsule 3x weekly, once daily after eating a fatty dinner. Then don’t take it for 4 days. Replicate this cycle each week.
- Vitamin E 800 U/I. Consume one capsule or some other version daily after eating without stopping.
- Bio-Available Curcumin 600 milligrams. Consume one capsule twice daily after you eat breakfast and lunch without stopping.
- CBD oil 25 milligrams. Consume one to two drops (a total of~25 milligrams) under your tongue daily prior to bedtime.
- Tumour marker steady checks every few months, routine annual cancer imaging tests. If there’s not any cancer relapse after five years, reduce the test frequency.
Avoiding cancer for somebody who was always free of cancer – prophylactic procedure
- Fenbendazole 222 milligrams. Consume one capsule 3x weekly, once daily after eating a fatty dinner. Then don’t take it for 4 days. Duplicate this for ten weeks. Halt for ten weeks. Then replicate the cycle once more.
- Vitamin E 800 U/I. Consume one capsule or some other kind daily after eating without stopping.
- Bio-Available Curcumin 600 milligrams. Consume one capsule twice daily after eating breakfast and lunch without stopping.
- CBD oil 25 milligrams. Consume one to two drops (a total of ~25 milligrams) under your tongue daily prior to bedtime.
Does Fenbendazole cause Liver Damage?
Although fenbendazole is generally well tolerated, there have been reports of elevated liver enzymes from the use of Fenbendazole, as well as the similar human medications mebendazole and albendazole.Therefore, patients should get a blood panel that includes the liver enzymes of AST, ALT, Alkaline Phosphatase, before taking Fenbendazole.
Liver enzymes may be elevated from cancer treatments, alcohol use, certain medications, and cancer itself.
Elevated liver enzymes indicate a liver that is stressed and inflamed, and adding to its burden with Fenbendazole would not be recommended.
Elevated liver enzymes may actually be a good sign for a cancer patient taking fenbendazole. Those liver enzyme (AST, ALT) values may spike for one or two months as the liver is stressed by the influx of dead cancer cells as it filters and processes the cellular debris from those dead cancer cells. AST and ALT increasing is a sign of hepatic stress (work), not necessarily disease, in the context of fenbendazole use. These liver enzymes usually normalize after the cancer is eradicated by fenbendazole.
FYI, liver enzymes will also fluctuate with other non-cancerous sicknesses/recoveries as dead cellular debris enters the bloodstream and is processed by the liver for removal. This is part of a normal physiological process. Temporary liver enzyme fluctuation should be expected to occur as a matter of course when using fenbendazole as fenbendazole kills the cancer cells.
If a patient has elevated liver enzymes, liver damage, liver metastasis, or liver diseases, it is important to work with a health professional who is familiar with the use of Fenbendazole and can advise whether it can be used and/or monitor lab values. A typical dose of 250mg of Fenbendazole usually does not cause side effects, but vigilance is key due to the lack of extensive studies on its effects in humans.
Generally, for those with normal lab values, after one month of Fenbendazole treatment, patients should get a comprehensive metabolic panel (CMP). This standard blood test will check the liver and kidney function to assure that the patient is tolerating Fenbendazole without any concerning impacts on the vital organs.
If you decide to continue using this combination, closely monitor for potential side effects, such as gastrointestinal issues from metoclopramide or liver problems from acetaminophen.
In conclusion, while there is no specific evidence of harmful interactions between metoclopramide, acetaminophen, and fenbendazole, the experimental nature of fenbendazole’s use in humans necessitates caution and vigilant monitoring of the patient’s health. Be sure to regularly check liver enzyme levels to manage any emerging issues effectively.
We would still recommend taking at least 1 day off per week to avoid overstressing the liver if the medication is to be used for prolonged periods of time (like months or years).
To keep the liver health optimal, we advise you to take 250 mg capsules of Milk Thistle or 150 mg of Silymarin daily as a supportive supplement for keeping it in great shape.
How is Fenbendazole Best Administered?
Enhancing the Bioavailability of Fenbendazole with Oleic Acid. Oleic acid is a fatty acid that occurs naturally in various animal and vegetable fats and oils. The most readily available, oleic acid-rich, practical substance is olive oil. Most likely due to its role as an emulsifying agent, Liu et al (2018) found that pairing mebendazole with oleic acid (olive oil) greatly enhances the bioavailability of mebendazole. The magnitude of the effect was substantial, 1.6 to 2.8 times greater serum levels of mebendazole were obtained when co-administering mebendazole with various oils compared to controls. Olive oil was the most effective mebendazole booster. As should be expected, the increased serum levels of mebendazole translated into more effective parasite killing effects in the animals models used as well.Administration of Fenbendazole
The practical application of interactions of fenbendazole with the substances mentioned above are straight forward. To maximize the likelihood of ingested fenbendazole getting into the blood stream to kill distant cancer cells, helping absorption is wise. Whether you choose to take fenben with a fatty meal, mixed in a tablespoon of olive oil or both, these actions should deliver more bang for your buck with respect to more of the fenbendazole surviving digestive degradation to deliver more cancer killing punch.UPDATE: A chemist recently wrote in suggesting that fenbendazole taken with a teaspoon or so of butter would have optimal absorption characteristics…”take it with a small amount of saturated or monounsaturated fat — something with a carbon chain above 14, to optimize absorption. Butter is an ideal choice.” She estimated that approximately 85% of the ingested fenbendazole would survive first-pass metabolism* en route to the target cells.
Taking fenbendazole is one thing, making sure it is actually absorbed can be a matter of life or death.
Absorption Issues with Fenbendazole
There was recently an instance of a person with small cell lung cancer (SCLC) who had eradicated 90%+ of his tumors with fenbendazole but then he started to feel pain and diagnostic testing showed the tumors returning. We probed and found that, rather than his wife administering the fenben in yogurt as she did initially, when he started to feel better he self-administered his fenben by mixing it into his morning coffee. His wife was asked to run her finger along the inside of his coffee mug. Fenbendazole residue was coating the mug. He immediately switched to liquid fenben and within a week the pain subsided, and in 6 weeks all the lung tumors were gone. This just happened over the past few months (detailed Case Report to come).Manufacturers of Fenbendazole: Does the Brand Matter?

We get asked constantly whether there is a difference in effectiveness between the brands. We have not done any analyses on any of the products. However, we can report that all of the products listed above have been identified as instrumental in eradicating various cancers in the various Case Reports presented here. As such that evidence would seem to argue that all the brands are equivalent in function.However, we specifically don’t recommend, endorse or ding any brand because all that matters is that it works. And so far, they all appear to work. Use whatever you’re comfortable with, we have no evidence that the brand used matters.
Where to buy Fenbendazole for Humans
In our experience and the experiences of those that write in, it appears that the three readily available brands of fenbendazole (Panacur-C, FenBen Labs, Happy Healing Labs) are equally effective. Panacur-C can be obtained locally in pet stores, while they all can be obtained from Amazon.Fenbendazole in Humans FAQs
Can fenbendazole be taken in tablet, liquid or powder?
Fenbendazole is available in powder (Panacur). There may be other formulations available, but those are the
primary products that patients are using.
Since fenbendazole is a veterinary medicine, and is not licensed for human use and there is no specific human safety data available. The similar human forms of this class of medications, mebendazole and albendazole, have been used for parasitic infections for many years and have a good safety record. Fenbendazole has been reported to have a very low degree of toxicity and a high degree of safety in animal experiments. Do not follow the weight-dependent dosing (for dogs) that is given on the back of the packaging! According to the product description on Amazon, fenbendazole is "Safe for all Dogs 6 weeks and older, including pregnant Dogs".
Although fenbendazole is generally well tolerated, there have been reports of elevated liver enzymes from the use of fenbendazole, as well as the human medications mebendazole and albendazole.
I’ve found a Fenbendazole brand which is not made by Merck, is it ok?
There are a variety of opinions on which product is best, but no research exists that compares the effectiveness of various formulations in humans. Merck and Safeguard are well established companies whose products have been safety tested in animals and used by veterinarians for many years.
Would the fenbendazole protocol work with conventional treatment? - chemotherapy?
Yes, fenbendazole has the potential to synergize with conventional treatments, and possibly enhance treatment response. Some aspects of the protocol, such as vitamin E and curcumin, may interfere with chemotherapy and radiation due to their anti-oxidant properties.
Some people take it 3 day on 4 off, some 1 gram a day, some 2 or even 4 grams a day. What is the correct dosage?
Joe Tippens, who popularized the use of Fenbendazole for cancer, recommends 222 mg for three consecutive days, then four days off. There are many people who take larger doses, more frequently. Since Fenbendazole is not licensed for the treatment of cancer in humans, there is no correct dose that is supported by research, pharmacists or physicians. The dose you choose to take should be assessed based on your other medications and treatments, your type of cancer, prognosis, organ function and lab values in consultation with a trusted healthcare provider.
How long do I need to be on fenbendazole?
This will be up to you based on your treatment response to the protocol. It is reported that Joe Tippens continues to use the maintenance protocol for prevention of relapse. Monitor cancer markers and liver enzymes. If cancer markers are normal or liver enzymes are high, take a break.
How do I know when it is time to dose up?
This is an individual decision based on treatment response, tolerance, absorption, other treatments/medications and lab values.
Following anecdotal fenbendazole cancer success stories to treat their cancer, researchers have been experimenting with the “repurposed” use of Fenbendazole for cancer in humans. Though the Fenbendazole studies are limited, what researchers have found so far is promising for patients with cancer.
Fenbendazole has not received approval from the Food and Drug Administration (FDA) for treating cancer in humans. However, many cancer patients report positive effects from taking the medication.
For those exploring the fenbendazole protocol, it’s important to carefully consider dosage based on reported practices, while also consulting a healthcare provider to monitor safety.
Conclusion
Fenbendazole shows promise in preclinical anticancer research and user testimonials, with a generally favorable safety profile marked by mild, infrequent side effects. However, risks like liver toxicity and interactions demand caution, particularly for self-users. Always consult a doctor. Clinical trials are needed to validate its efficacy and long-term safety in humans. For more on the Joe Tippens Protocol, refer to our Joe Tippens Protocol main guide. Remember, this is not medical advice; individual results vary.- https://healnavigator.com/blog/fenbendazloe-side-effect-humans/
- https://alternativemedicine.com/cancer/facts-you-might-not-have-known-about-fenbendazole/
- https://www.fenbendazole.org/fenbendazole-information/fenbendazole-safety-and-side-effects/
- Fenbendazole and Cancer - at least 12 Anti-Cancer Mechanisms of Action - Dr William Makis
- Targeting the Mitochondrial-Stem Cell Connection in Cancer Treatment: A Hybrid Orthomolecular Protocol.
- Fenbendazole Cancer Success Stories: more than 150 Case Reports Compilation
- Fenbendazole vs Mebendazole for Cancer
- Fenbendazole vs Ivermectin for cancer
- Top 10 cancer fighting supplements
- Joe Tippens Protocol Fenbendazole
- Fenbendazole: Questions Answered, Things to Know, Useful Tips
- Best Ivermectin Dosage for Humans with Cancer or Different Cancer Types
- Mel Gibson had 3 Friends cure their Stage Four Cancer with Fenbendazole and Ivermectin
- Turbo Cancer Debunked
New & Improved Joe Tippens Protocol
- Fenbendazole is commonly taken at 300 mg for six days a week, with doses increasing to up to 1 gram in cases of aggressive "turbo cancers."
- Ivermectin (24 mg, 7 days a week) or in the case of severe turbo cancers up to 1mg/kg/day.
- Bio-Available Curcumin (600mg per day, 7 days a week).
- Vitamin D (62.5 mcg [2500 IU] seven days a week).
- Enhanced absorption Berberine (500mg per day) if you are trying to starve your cancer of sugars.
- Diet and Lifestyle: Removing sugar from one’s diet is crucial during this protocol (BMJ 2023), eating a nutritious fresh whole-food diet with fruits and vegetables, avoid ultra processed foods (BMJ 2024) and a healthy lifestyle with less stress.
- Statements on this website have not been evaluated by the Food and Drug Administration. The contents of this website is for educational and informational purposes only and is not intended to be a substitute for professional medical advice, diagnosis or treatment.
- Please do not consider this guide as personal medical advice, but as a recommendation for use by professional providers. Consult with your doctor and discuss with her/him. Our aim here isn't to replace your doctors' advice. It is intended as a sharing of knowledge and information. Do take note that cancer is a continuous struggle between the immune system and the cancer cells. Cancer treatments are meant to assist the immune system in this battle.
- The case reports presented reflect the real-life experiences and opinions of other readers or users of the website. The experiences of those readers or users are personal to those particular readers/users and may not necessarily be representative of all readers/users. We do not claim, and you should not assume, that all other readers/users will have the same experiences. Do you own research, consult with relevant medical professionals before attempting to self-treat for any condition.
- Cancer treatment should be part of a multi-modal approach in order to provide the best possible outcome. Diet and lifestyle changes are meant to run alongside conventional treatment. They are complementary, not alternative.
- Cancer care is a team effort with the patient at the centre. Care should be supervised and coordinated by a primary healthcare provider. Patients with cancer should consult with their regular oncologist as well as an integrative provider/oncologist, in addition to their primary care provider and the supporting nurses, dieticians and other allied healthcare professionals.
- While the term 'alternative' might imply opposition to conventional oncology, we prefer 'complementary,' 'integrated,' or 'holistic.' These terms better reflect the role of these strategies as part of a personalized value-added menu of strategies, ensuring the most effective and safe solutions for patients.
- Integrating a repurposed drug doesn't mean rejecting modern medicine — It enhances it and offers a more comprehensive approach to wellness and healing. By combining conventional cancer management with root-cause resolution, this model creates a path to sustained recovery and resilience.
The Wellness Company's Ivermectin and Mebendazole
Ivermectin and mebendazole, both approved for human use, are now available in the U.S.
Researched and approved by Dr. Peter McCullough.
- Prescribed by licensed medical professionals
- Compounded and dispensed by a licensed US-based pharmacy
- Approved for human use
I have polycystic kidney disease and polycystic liver disease with minor elevated values, when I take Fenbendazole I feel like I just had 3 beers. I don't think that is normal so I have decided to stop. I get monoclonal antibodies for my cancer every 28 days and have been in NCR for 4 years now. If my cancer gets worse, I will reconsider taking but for now the side effects are too strong to continue.
ReplyDeleteAnonymous, I wish you well.
DeleteThe original Tippens protocol used alpha tocopherol succinate, which some studies had shown worked against cancer. Normal vitamin E in stores is usually alpha tocopheral acetate, which studies indicate does not work, including the SELECT trial. Updated Tippens protocol uses vitamin E with all forms - tocotrienals and tocopherals, gamma as well as alpha, etc
ReplyDeleteI was diagnosed yesterday with a Duodenal Ulcer and just started treatment with Omeprazole and Carafate. I was taking IVM & Fenben for prostate cancer and it has reduced the size of the lesions, Question: Can I take IVM & Mebendazole with a Duodenal Ulcer or do I need to wait until the ulcer is healed?
ReplyDelete