Exploring the Anticancer Potential of Fenbendazole: A Review of 137 Anecdotal Case Reports and Emerging Evidence (2025)

Abstract

Fenbendazole (FBZ), a benzimidazole-class anthelmintic primarily used in veterinary medicine, has garnered attention for its potential anticancer properties. This review examines anecdotal reports and case studies regarding the use of fenbendazole, an anthelmintic agent traditionally used in veterinary medicine, as a potential anticancer treatment in humans. A compilation of 137 case reports across various cancer types, including breast, lung, colorectal, prostate, and pancreatic cancers, is analyzed to assess the validity of these claims. While these anecdotal accounts suggest potential anticancer effects of fenbendazole, the lack of controlled clinical trials necessitates caution. Healthcare professionals should be consulted before considering fenbendazole as a treatment option.

Keywords: Fenbendazole; Anthelmintic; Drug repurposing; Cancer treatment; Case reports; Ivermectin; Mebendazole

Introduction

Managing aggressive cancers requires a highly individualized, multidisciplinary, or multimodal approach. Standard treatment options—including surgery, chemotherapy, radiation therapy, targeted therapy, and immunotherapy—are carefully selected and combined based on the specific characteristics of the tumor and patient-related factors. Since there is no universal treatment protocol that applies to all cases, adherence to evidence-based guidelines and continuous reassessment of therapeutic strategies remain essential for effective cancer management.

Despite significant advances in medical oncology, including targeted therapies and immunotherapies, the development and approval of new cancer drugs remain slow and costly, with the U.S. Food and Drug Administration (FDA) authorizing only 10–20 oncology drugs annually (source). Global spending on oncology drugs exceeded $150 billion in 2022 and rose to $223 billion in 2023, with projections reaching $409 billion by 2028, underscoring the escalating economic impact of cancer treatment (source, source).

 

However, access to effective, cancer-specific therapies remains limited, particularly in low- and middle-income countries where cancer survival rates lag behind those in high-income settings due to inadequate funding and infrastructure (source, source). This has led to increased interest in repurposing existing drugs as more affordable alternatives. Exploring such options may provide valuable insights and potential solutions for expanding treatment accessibility, warranting further scientific investigation.

Given the complexity of cancer treatment, it is crucial for patients to consult a specialized oncology team to determine the most appropriate course of action for their specific diagnosis.

One emerging area of interest in recent years is the potential use of fenbendazole (FBZ) as either a standalone treatment or a complementary therapy alongside conventional treatment for various forms of cancer. FBZ is a widely available and cost-effective deworming medication primarily used in veterinary medicine, commonly sold in pet stores and through commercial websites. Its accessibility and affordability have contributed to growing public interest in its possible anti-cancer properties.

Despite numerous anecdotal reports and media coverage suggesting that FBZ may be effective in treating metastatic cancer, there is currently not enough clinical literature supporting its use as an anti-cancer agent. Scientific studies on FBZ have largely focused on investigating its mechanism of action in animal models rather than evaluating its efficacy in human patients [2].

This paper aims to critically assess these anecdotal success stories and examine whether they provide a strong scientific basis for further investigation into FBZ as a potential cancer treatment.

Methods

Data was sourced from a compilation of 137 case reports published on OneDayMD.com (1), detailing individual experiences with fenbendazole as a cancer treatment, sourced from social media, patient testimonials, and clinical communications between 2023-2025 (One Day MD).

These reports were categorized by cancer type, and outcomes were assessed based on self-reported measures such as tumor regression, remission status, and overall survival. It is important to note that these reports are anecdotal and lack the methodological rigor of controlled clinical studies.

Results

The anecdotal reports included in this compilation cover a variety of cancer types and describe self-reported outcomes following the use of fenbendazole. These findings, while compelling, must be interpreted cautiously due to the inherent limitations of the data sources. Key observations include:

1. Breast Cancer

   • Sixteen cases of breast cancer including metastatic breast cancer reported outcomes such as tumor shrinkage or remission.
   • A majority of these cases involved early to moderate-stage disease, with some patients combining fenbendazole with standard treatments like chemotherapy and hormonal therapy.
   • One notable case involved a patient with metastatic triple-negative breast cancer achieving remission after six months of fenbendazole use, alongside a ketogenic diet and immune-supportive supplements.

2. Lung Cancer

   • Eleven cases, primarily non-small cell lung cancer (NSCLC), highlighted improved survival rates and tumor regression.
   • One patient with advanced NSCLC demonstrated significant tumor shrinkage within three months of incorporating fenbendazole alongside checkpoint inhibitors.
   • Joe Tippens, diagnosed with Stage 4 small-cell lung cancer that had metastasized to multiple organs, reported complete remission after incorporating fenbendazole into his treatment protocol. His case has been widely discussed and has sparked significant interest in FBZ as a potential anticancer agent. (4)

3. Colorectal Cancer

   • Sixteen cases, patients reported tumor reduction, remission, or disease stabilization.
   • The most striking outcome was from a patient with stage IV colorectal cancer (metastatic colon cancer) achieving no evidence of disease (NED) status after integrating fenbendazole with conventional therapies and dietary modifications.

4. Pancreatic Cancer

   • Eleven cases involved pancreatic cancer, an aggressive malignancy with limited treatment options.
   • While outcomes were generally less pronounced than in other cancers, one patient with advanced pancreatic cancer experienced prolonged survival (beyond two years) after initiating fenbendazole, a rare occurrence for this disease.

5. Other Cancer Types

• Reports included melanoma, metastatic prostate cancer, glioblastoma, and ovarian cancer, with mixed outcomes. Some patients indicated significant clinical improvement, including reduced tumor markers and alleviated symptoms. Below is a selection of these cases:

• Case 1: A man with glioblastoma multiforme, a highly aggressive brain tumor, began taking fenbendazole and experienced an unexpected halt in tumor progression over a six-month period.

• Case 2: A patient with advanced ovarian cancer incorporated fenbendazole and reported a substantial decrease in CA-125 levels, suggesting tumor response.

• Case 3: A 45-year-old man with prostate cancer noted a decline in PSA levels and tumor size after adding fenbendazole to his integrative treatment strategy.

• Case 4: A 72-year-old patient with late-stage liver cancer introduced fenbendazole into his treatment regimen and demonstrated an improvement in liver function tests and general well-being.

• Case 5: A patient diagnosed with metastatic melanoma observed a reduction in lesion size and a prolonged progression-free survival period after adding fenbendazole to their therapy.

• Case 6: A 58-year-old woman with endometrial cancer reported a positive clinical response, including decreased tumor markers and improved overall health, following fenbendazole use.

Emerging Patterns

A qualitative analysis of the reports revealed the following commonalities:

• Combination Therapies: Many patients combined fenbendazole with conventional cancer treatments (e.g., chemotherapy, radiotherapy, immunotherapy) and other repurposed drugs (e.g., ivermectin, mebendazole), making it challenging to isolate fenbendazole’s specific effects.
• Supplement Use: A high proportion of patients also reported using supportive supplements, such as vitamins (e.g., D3, C), curcumin, zinc, berberine, and melatonin, which may have contributed synergistically to the observed effects.
• Consistency and Dosage: Regular and sustained use of fenbendazole appeared to correlate with better-reported outcomes. Dosages ranged from 222 mg (a standard veterinary dose) to 1 gram per day, depending on individual protocols.

Limitations

While the results are promising, several limitations are evident:

• Sample size: Sample size for this treatment is N of 137.
• Self-Reported Data: The reliance on anecdotal reports introduces potential biases, including placebo effects and selective reporting.
• Concurrent Therapies: The concurrent use of conventional treatments makes it difficult to attribute observed benefits exclusively to fenbendazole.
• Lack of Clinical Context: Details such as exact tumor size, staging, and clinical follow-up were often missing, reducing the rigor of the analysis.
• Small Sample Size: Although 137 reports were reviewed, the sample size is insufficient to draw statistically significant conclusions across different cancer types.

Potential Mechanisms of Action

Emerging preclinical studies provide plausible mechanisms for fenbendazole’s effects on cancer:

• Microtubule Disruption: Fenbendazole disrupts microtubule dynamics, interfering with cancer cell division and inducing apoptosis. (3)
• Metabolic Effects: It inhibits glucose uptake in cancer cells, potentially starving them of energy.
• Immune Modulation: Anecdotal evidence suggests that fenbendazole may enhance immune responses, although this requires further investigation.

Discussion

The anecdotal nature of these reports precludes definitive conclusions about the efficacy of fenbendazole as a cancer treatment. However, the consistency of positive outcomes across diverse cancer types suggests a potential biological effect that merits further investigation. 

The pattern of case reports also suggests that fenbendazole may exhibit broad-spectrum anticancer properties.

Comparatively, other repurposed anthelmintic drugs, such as mebendazole, have progressed further along the clinical research pipeline, with some reaching early-phase human trials. 

Given the current lack of clinical evidence, it is imperative that patients consult healthcare professionals before considering fenbendazole as a treatment option. Unsupervised use may lead to unforeseen drug interactions or adverse effects.

Future Directions

To address these challenges and advance the understanding of fenbendazole’s role in oncology, the following steps are recommended:

• Controlled Clinical Trials: Randomized, double-blind studies are essential to establish fenbendazole’s efficacy and safety in humans.
• Mechanistic Studies: Further research into fenbendazole’s molecular targets and pathways will clarify its anticancer properties and identify potential biomarkers of response.
• Combination Therapy Research: Studies exploring fenbendazole in combination with standard treatments, such as chemotherapy and immunotherapy, may uncover synergistic effects.

Conclusion

The consistency of anecdotal outcomes, supported by plausible preclinical mechanisms, positions fenbendazole as a promising candidate for further investigation in oncology. 

Given the potential benefits of FBZ with what seems to be a limited toxicity profile, further research is warranted to evaluate the clinical settings in which this medication may be beneficial and repurposed for patients with progressive malignancy and possibly other malignant settings as well.

However, until robust clinical evidence is available, healthcare providers must guide its use with caution, and patients should not substitute it for evidence-based treatments. Collaborative efforts between researchers, clinicians, and regulatory bodies are essential to unlock fenbendazole’s full therapeutic potential while safeguarding patient safety.

References

1. OneDayMD (2025). Fenbendazole Cancer Success Stories: 137 Case Reports Compilation (April 2025 Edition). https://www.onedaymd.com/2024/02/fenbendazole-cancer-success-stories.html
2. Dogra N, Kumar A, Mukhopadhyay T (2018). Fenbendazole acts as a moderate microtubule destabilizing agent and causes cancer cell death by modulating multiple cellular pathways.Sci Rep 8: 11926.
3. Anticancer Research (2024). Oral Fenbendazole for Cancer Therapy in Humans and Animals. https://ar.iiarjournals.org/content/44/9/3725
4. Tippens, J. (2019). Personal Account of Fenbendazole Use in Stage 4 Cancer. OneDayMD.
5. Dr John Campbell (2025). https://www.facebook.com/watch/?v=1288010582424486. Facebook.

Research opportunities - Dr John Campbell

New & Improved Joe Tippens Protocol

According to Dr William Makis, Canadian oncologist, the holy grail turbo cancer cure may just be the synergistic combination therapy of Fenbendazole AND Ivermectin:

• Fenbendazole (300mg, 6 days a week) or in the case of severe turbo cancers up to 1 gram.

• Ivermectin (24mg, 7 days a week) or in the case of severe turbo cancers up to 1mg/kg/day (Find a Doctor)

• Bio-Available Curcumin (600mg per day, 7 days a week).

• Vitamin D (62.5 mcg [2500 IU] seven days a week).

• 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 quality sleep and proper stress management.

• Enhanced absorption Berberine (500mg per day) if you are trying to starve your cancer of sugars.

Note on Vitamin E:  

According to a July 22, 2020 update by Joe Tippens:

"I have eliminated Vitamin E as a required part of the protocol as there are simply too many instances (eg, blood thinners) where it needs to be eliminated, and it is the least important of the items."

Adapted from: https://www.onedaymd.com/2024/11/fenbendazole-and-cancer-15-minutes-with.html

Related: 

• Mebendazole vs fenbendazole for cancer

• Ivermectin vs Fenbendazole for Cancer

• Best Ivermectin Dosage for Humans with Cancer or Different Cancer Types

• Top 18 Repurposed Drugs and Metabolic Interventions to Control Cancer

• Joe Tippens Protocol Fenbendazole

• Ivermectin and Fenbendazole: Treating Turbo Cancer

• Fenbendazole: Questions Answered, Things to Know, Useful Tips

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