Viral copypasta posts mislead about cancer causes and testing, promote unproven cancer remedies such as ivermectin, fenbendazole, alkaline water, and vitamin B17

In late January 2025, “copypasta” posts containing multiple claims about cancer went viral on Facebook. The term copypasta is Internet slang for a block of text that is directly copied and pasted many times across social media platforms. These messages often call on users to share this information to others in their circle, and have been used to spread misinformation that goes viral online.

Such is the case of these Facebook posts, which include previously debunked claims about cancer causes and testing and a long list of unproven and disproven cancer remedies. The posts paired these claims with a picture of the U.S. Secretary of Health and Human Services nominee Robert F. Kennedy Jr. (see below).

The posts also claimed, “Before the advancements of the pharmaceutical industry, natural methods were successfully used to treat certain cancers”. Some posts appeared to attribute this quote to Kennedy. While Kennedy has a long history of spreading health misinformation and conspiracy theories, we found no evidence that these words are his nor that he endorsed the claims made in these posts.

The posts gathered hundreds of thousands of engagements on Facebook. Posts also circulated on other social media platforms, including Instagram, X (formerly Twitter), and TikTok.

Misinformation about cancer prevention and treatment is dangerous. First, it can expose people to potentially harmful products, like some of those listed in the copypasta posts. Second, the false sense of hope associated with alleged miracle cures may lead some patients to delay diagnosis and effective medical treatment, reducing their chances of survival.

Below, we will analyze the multiple false claims made in the post.

Claim 1 (Incorrect):

“Avoid testing for the tumor. Tumors serve to protect the body by preventing cancer cells from spreading. Drilling them for a test can aggravate the situation by allowing the cells to migrate.”

Tumors are abnormal masses of tissue that are made up primarily of cells that multiply uncontrollably. However, not all tumors lead to cancer. Some may progress into cancer, while others won’t.

Cancer is a genetic disease, that is, it is caused by changes to genes (mutations), particularly those controlling cell growth and division. This doesn’t mean that all cancers are caused by inherited mutations—only 10% of them are—because mutations can occur in single cells as an adult due to aging or exposure to agents that have direct or indirect effects on our genes. Some factors that can increase our risk of developing cancer are tobacco and alcohol consumption, an unhealthy diet, physical inactivity, and exposure to pollutants or certain chronic infections.

Cancer screening tests like biopsies don’t change our genes and therefore, they don’t cause cancer.

This claim arises from the incorrect belief that tumors act as a trap for toxins or cancer cells that, if disturbed, can be released and lead to cancer.

The claim contains a grain of truth, though, in that biopsies carry a potential risk of spreading the cancer if not done correctly. However, clinicians are well aware of this risk and take precautions to minimize it.

For example, the Roswell Park Comprehensive Cancer Center stated that an “improperly performed biopsy can cause some cancer types, such as a sarcoma, to spread”. Sarcomas are cancers that develop in the bones and soft tissues including fat, muscles, blood vessels, and nerves. The U.S. National Cancer Institute and the Canadian Cancer Society explain that this risk is extremely low and depends on the type and stage of cancer. In cases that can’t be safely biopsied, doctors remove the tumor completely without taking a biopsy.

Claims questioning the usefulness and safety of cancer testing tend to be overly simplistic. When applied properly, screening is a useful tool for detecting cancer early, which makes treatment easier and increases the chances of survival^[1]. However, cancer screening is complex and might not be recommended for everyone.

For some types of cancer, including cervical cancer and breast cancer, screening has been demonstrated to save lives. In other types of cancer, like prostate cancer, the benefits of widespread screening aren’t so clear.

Also, certain screening tests may be recommended only for people who have a high risk for that type of cancer, for example, because they have certain gene mutations, a family history, or are exposed to cancer-causing agents like tobacco smoke or chemicals.

In summary, cancer screening tests don’t cause cancer but can instead save lives. That doesn’t mean that they are recommended for everyone. Some tests carry risks that need to be weighed against the benefits for each individual. Understanding this risk-benefit balance can help patients to make informed decisions.

Claim 2 (Incorrect):

“Cancer starts with a parasite”

As we explained above, cancer results from mutations that cause the cells to proliferate without control. Infections with certain harmful microorganisms, including specific parasites, are one of the multiple factors that can increase the risk of some types of cancer. But cancer isn’t solely caused by parasites.

As we reported in an earlier review, the U.S. National Cancer Institute told Science Feedback that while certain parasites can cause cancer, “there are many other risk factors that have been identified, and that the presence of a risk factor is not a guarantee that cancer will develop”.

The International Agency for Research on Cancer (IARC), part of the World Health Organization (WHO), recognizes chronic infection with three types of worms as cancer-causing (Group 1 carcinogens). One is Schistosoma haematobium, which is associated with bladder cancer^[2]. The other two are Opistorchis viverrini (liver flukes) and Clonorchis sinensis, both associated with cholangiocarcinoma, a cancer affecting the bladder and the bile ducts of the liver.

Current evidence points to three main mechanisms by which the interaction between parasite and host may cause cells to become cancerous. These mechanisms include “chronic inflammation, oxidative stress caused by parasite-derived products, and host tissue damage by the parasite during infection”^[3].

However, parasitic infections are only a major cause of cancer in regions where these worms are endemic. For example, in regions where infection with O. viverrini and C. sinensis are very common, such as sub-Saharan Africa and Southeast Asia, these parasites are responsible for the majority of all cases of bladder and liver cancer. But this isn’t the case in other regions, where most cancers result from a combination of genetic and environmental factors.

Claim 3 (Unsupported):

“Consider using Ivermectin and Fenbendazole to combat [cancer]”

Many who claim that cancer is caused by parasites also promote the use of antiparasitic drugs as a cure. For the past few years, drugs such as hydroxychloroquine, ivermectin, and fenbendazole have been touted online as effective treatments or even cures for cancer.

Such claims went viral again in January 2025 after actor Mel Gibson suggested in an interview for the podcast The Joe Rogan Experience that ivermectin and fenbendazole cured three of his friends of late-stage cancer.

Contrary to these claims, there is no scientific evidence that supports the use of antiparasitic drugs in people with cancer, as Science Feedback explained in multiple reviews.

Hydroxychloroquine is approved in humans to prevent and treat malaria and some autoimmune conditions such as rheumatoid arthritis and lupus. Ivermectin is included in the WHO’s List of Essential Medicines for its effectiveness against several parasitic diseases in humans.

Fenbendazole, on the other hand, is a broad-spectrum dewormer used in animals that isn’t approved for human use either in Europe or in the U.S.

All three drugs have shown anticancer effects in laboratory cells and mice, sometimes with mixed results. For example, while some studies showed that hydroxychloroquine^[4] and chloroquine—another antiparasitic drug highly similar to hydroxychloroquine—slowed tumor growth^[5,6], others found that hydroxychloroquine accelerated tumor growth^[7] or interfered with cancer treatment^[8]. Early-phase clinical trials with hydroxychloroquine are ongoing to evaluate its efficacy as a cancer treatment.

So far, neither hydroxychloroquine, ivermectin, nor fenbendazole has been demonstrated to be a safe and effective treatment for people with cancer. And while they are well-tolerated at the doses and uses for which they are approved, they can cause serious side effects and even fatal overdoses.

Claim 4 (Incorrect):

“Cut back on the sugar. Sugar feeds cancer cells, so it is important to avoid all forms of sugar.”

There is no scientific evidence supporting the common myth that sugar causes or aggravates cancer. There is also no scientific basis for the belief that eliminating sugar from the diet cures cancer or slows its growth, as Science Feedback showed in earlier reviews.

This claim stems from a misconception of cancer cell metabolism. In the 1920s, scientist Otto Warburg found that cancer cells tend to consume much more glucose than normal cells because of their uncontrolled proliferation^[9].

This gave rise to the belief that removing sugar from the diet would starve cancer cells and keep them from growing. But this is an oversimplification that doesn’t hold true.

There are many types of sugar, and some are naturally present in various healthy foods, such as fruit, vegetables, and grains. Glucose, the simplest form of sugar, is an important source of energy for healthy cells. When cells can’t access this source of energy, things go wrong. For example, when cells can’t obtain enough glucose—something that can happen in people with diabetes—it can lead to a serious illness called diabetic ketoacidosis.

Moreover, when the body doesn’t get enough glucose, cells will seek to obtain it from other sources, namely protein and fat. The Dana-Farber Cancer Institute explained that this process, called gluconeogenesis, can cause problems in the medium term, as it can lead to muscle loss and malnutrition.

Sugar can, however, increase the risk of cancer indirectly. Due to its high caloric content, eating too much sugar—particularly added sugars— can result in weight gain. Overweight and obesity are known risk factors for cancer. The IARC recognizes obesity as a cause of at least 13 different types of cancer.

That said, simply removing sugar from the diet won’t cure cancer. Instead, it might cause harm to patients by depriving healthy cells of an important source of energy. As with many things in life, the key to health is balance: neither too much nor too little.

Claim 5 (Unsupported):

“Use hydrogen peroxide (H2O2). This compound contains an extra oxygen molecule that cancer cells do not tolerate. Apply it to skin with a cotton or toilet glove, especially after a bath or shower for better absorption”

Hydrogen peroxide is a colorless liquid used as a general disinfectant and antiseptic at concentrations below 10%. There is no evidence that rubbing it on the skin will kill cancer cells, a claim that has been debunked by Full Fact, Reuters, USA Today, and AP News, among others.

A few small studies have investigated the effects of hydrogen peroxide on people with cancer. However, the conditions in those studies are very different from what the posts proposed.

For example, one pilot trial evaluated whether a combination of radiotherapy and hydrogen peroxide injected into breast tumors could shrink the tumor in 12 patients. The method was safe, but the researchers couldn’t determine how much of the observed effect was due to hydrogen peroxide and how much to radiotherapy^[10].

Another study found that rubbing 33% hydrogen peroxide reduced the size of the lesions caused by non-melanoma skin cancers of the head and neck in 11 patients^[11]. However, hydrogen peroxide was applied specifically to the lesion—not indiscriminately over healthy skin, as the posts proposed—and the lesions were surgically removed at the end of the treatment.

Tyler Johnson, a clinical assistant professor of oncology at Stanford Medicine, told Reuters that hydrogen peroxide rubbed on the skin could reach the bloodstream but won’t penetrate far enough into the body to reach most tumors.

In addition to the lack of evidence of a benefit, hydrogen peroxide is a bleaching agent that can be toxic if ingested, inhaled, or by contact with the skin or eyes. Applying hydrogen peroxide to the skin at a concentration above 35% can cause mild irritation. Higher concentrations at or above 50% can lead to severe burns, blisters, ulcers, and permanent scarring.

Claim 6 (Incorrect):

“Drink Alkaline Water. Alkaline water, like lemon juice, helps balance the pH of the body, making it difficult for cancer cells to survive”

The claim that ingesting alkaline foods or drinks like alkaline water prevents or treats cancer lacks scientific support, as Science Feedback explained in an earlier review. This claim is based on the incorrect assumption that cancer needs an acidic environment to proliferate, which arises from a misconception about the Warburg effect^[9].

Warburg found that, unlike healthy cells, cancer cells preferentially obtain energy from glucose fermentation, even when oxygen is available. This produces lactic acid as a by-product, increasing the acidity of the tumor’s surrounding tissue^[12]. Therefore, while tumors are often surrounded by an acidic environment, this is a consequence of cancer, not its cause.

The biochemical reactions that keep us alive can only take place in specific acid-base (pH) conditions. In fact, significant shifts in pH can lead to serious complications. For this reason, the body needs to keep the pH of cells and tissues within a very narrow range, which our diet can’t alter.

Claim 7 (Unsupported and Misleading):

“Take a detox bath. Add baking soda, borax, Epsom salt and bentonite clay to a hot bath. It helps to remove toxins from the body”

A wide assortment of “detox” and cleansing procedures are promoted on social media in the form of diets, supplements, and other strategies. However, the belief that a healthy person needs to “detox” regularly to prevent health problems is a common pseudoscientific myth.

These practices are, first of all, unnecessary, because the body has its own mechanisms for removing harmful substances. The liver and kidneys are the main organs responsible for this job and are highly effective. There is no evidence that “detoxes” and cleanses help to remove toxins from the body.

Moreover, some of these products and practices can be harmful. For example, restrictive diets can lead to dehydration or nutrient deficiencies. Some “detox” products have been found to contain hidden, potentially harmful ingredients like laxatives.

“Detox” baths with products like borax (sodium borate)—typically used as a household cleaner—became popular in 2023 thanks to a TikTok challenge that encouraged users to drink or bathe in borax to “detox” and lose weight. But this is a dangerous practice. Borax can be toxic when ingested or inhaled, and skin exposure to it can cause irritation and dermatitis. “Detox” baths containing borax, Epsom salts, and baking soda have been linked to severe cases of intoxication and liver injury.

In 2010, the European Union added borax to the Substance of Very High Concern list out of concerns that it might adversely affect human reproduction or development. As a result, certain products containing borax are banned from sale in Europe. In the U.S. borax isn’t banned, but the Environmental Protection Agency classifies it as a substance with “a high degree of acute toxicity”.

Claim 8 (Inaccurate):

“Consume vitamin B17, present in apple seeds and apricot seeds, this vitamin can help eliminate cancer cells”

The so-called “vitamin B17” is neither a vitamin nor a cancer treatment, as Science Feedback explained in the past. “Vitamin B17” is the name that some people use to refer to amygdalin, a compound present in some plants like clover and in the seeds of fruits from the Rosaceae family, such as bitter almonds, apricots, plums, and cherries.

A related, semi-synthetic compound called laetrile was proposed as a cancer treatment in the mid-1800s. However, this hypothesis was quickly disproven after initial studies showed it was ineffective and highly toxic. In the 2000s, however, claims about the compound’s alleged benefits were revived on social media, this time with laetrile being rebranded as “vitamin B17”.

In the intestine, amygdalin is broken down into hydrogen cyanide^[13], a potentially deadly poison that interferes with cells’ ability to use oxygen. Specifically, cyanide blocks the electron transport chain in the mitochondria, which produces most of the energy for the cell. The cell is thus deprived of oxygen and energy. This causes serious neurological and cardiovascular problems that can lead to death within minutes. At lower cyanide levels, oxygen-limited cells are forced to burn glucose for energy. This process produces lactic acid, which accumulates rapidly in the body and can lead to metabolic acidosis, a potentially fatal condition that impairs organ functions.

Cyanide poisoning can occur even at low doses. Most common symptoms include chest pain, changes in the rate of heart beating and breathing, confusion, nausea, and weakness. At high levels, cyanide can cause serious problems, including loss of consciousness, seizures, and coma that can lead to death.

In fact, the use of laetrile or amygdalin for therapeutic purposes has been associated with multiple cases of cyanide poisoning^[14]. Because of its toxicity, neither the U.S. Food and Drug Administration (FDA) nor the European Union permit the sale of laetrile or amygdalin-containing products. Regularly consuming apple and apricot seeds, as the posts recommended, can also expose a person to dangerous cyanide levels. According to the European Food Safety Authority, “Eating more than three small raw apricot kernels, or less than half of one large kernel, in a serving can exceed safe [cyanide] levels”.

Other unproven cancer remedies

The posts proposed specific doses of curcumin, cannabidiol (CBD) oil, vitamin E, and vitamin C in people with cancer. However, current evidence doesn’t support the use of any of these compounds as a cancer treatment.

Earlier reviews by Science Feedback showed that the potential anticancer effects of curcumin have been primarily observed in laboratory cells and mice. The few trials that have studied curcumin in people are preliminary and have produced mixed results.

Some studies suggest that CBD oil may help alleviate certain side effects from cancer treatment, including nausea, lack of appetite, anxiety, depression, and insomnia. But there is no evidence indicating that CBD is effective as a cancer treatment. The only medical use for which CBD oil is currently approved in Europe and in the U.S. is as a treatment for some severe forms of epilepsy.

Likewise, vitamin C and vitamin E can kill cancer cells in laboratory cells. But there is no clinical evidence they can reduce the risk of cancer or provide benefits to cancer patients. In the case of vitamin C, scientists continue to investigate its therapeutic potential when applied intravenously. However, there is currently no clinical evidence that it works in humans, nor has it been approved as a cancer treatment by regulatory agencies like the FDA.

Population-based studies on vitamin E supplementation suggest that it may reduce the risk of certain types of cancers, but increase the risk of others. Furthermore, vitamin E can interfere with some cancer treatments, like radiation therapy. In addition, high doses of vitamin E or long-term consumption may cause toxicity and increase the risk of stroke and all-cause death^[15].

Conclusion

The posts mislead about the causes of cancer and the benefits of cancer testing. In addition, they promote a list of alleged cancer treatments that are unproven or have been long disproven. None of them have demonstrated benefits in people with cancer, and some can lead to serious or potentially fatal complications.

REFERENCES

• 1 – Goddard et al. (2024) Estimation of Cancer Deaths Averted From Prevention, Screening, and Treatment Efforts, 1975-2020. JAMA Oncology.
• 2 – Antoni et al. (2017) Bladder Cancer Incidence and Mortality: A Global Overview and Recent Trends. European Urology.
• 3 – Tong et al. (2017) Parasite Infection, Carcinogenesis and Human Malignancy. eBioMedicine.
• 4 – Low et al. (2023) Hydroxychloroquine: Key therapeutic advances and emerging nanotechnological landscape for cancer mitigation. Chemico-Biological Interactions.
• 5 – Jiang et al. (2010) Antitumor and antimetastatic activities of chloroquine diphosphate in a murine model of breast cancer. Biomedicine and Pharmacotherapy.
• 6 – Loehberg et al. (2007) Ataxia Telangiectasia-Mutated and p53 Are Potential Mediators of Chloroquine-Induced Resistance to Mammary Carcinogenesis. Cancer Research.
• 7 – Chi et al. (2010) Disruption of Lysosome Function Promotes Tumor Growth and Metastasis in Drosophila. JBC.
• 8 – Wabitsch et al. (2021) Hydroxychloroquine can impair tumor response to anti-PD1 in subcutaneous mouse models. iScience.
• 9 – Liberti and Locasale (2016) The Warburg Effect: How Does it Benefit Cancer Cells? Trends in Biochemical Sciences.
• 10 – Nimalasena et al. (2020) Intratumoral Hydrogen Peroxide With Radiation Therapy in Locally Advanced Breast Cancer: Results From a Phase 1 Clinical Trial. International Journal of Radiation Oncology.
• 11 – Mundi et al. (2020) 33% hydrogen peroxide as a Neoadjuvant treatment in the surgical excision of non-melanoma skin cancers: A case series. Journal of Otolaryngology – Head and Neck Surgery.
• 12 – Rohani et al. (2019) Acidification of Tumor at Stromal Boundaries Drives Transcriptome Alterations Associated with Aggressive Phenotypes. Cancer Research.
• 13 – Haisman & Knight (1967) The enzymic hydrolysis of amygdalin. Biochemical Journal.
• 14 – Milazzo et al. (2015) Laetrile treatment for cancer. Cochrane Database of Systematic reviews.
• 15 – Miller et al. (2005) Meta-Analysis: High-Dosage Vitamin E Supplementation May Increase All-Cause Mortality. Annals of Internal Medicine.