An oncologist addresses growing misinformation around ivermectin for cancer treatment, explaining the limits of preclinical research, the lack of human clinical evidence, and the risks of replacing standard cancer care with unproven therapies.

In today's highly connected world, doctors are not only fighting cancer with medicines and technology, but we are also navigating the muddy waters of scientific misinformation about cancer treatments, misinformation that breeds mistrust and can cost lives.

Ivermectin is an antiparasitic drug that gained notoriety during the COVID-19 pandemic—a time when our phones, often our only connection to the world, were flooded with more false claims about COVID-19 treatments than actual scientific inquiry could keep up with. Many of these claims were fueled by influencers, right-wing media, and pop culture. It was sensational. It was mainstream. And the algorithms rewarded such content. But those rewards can be deadly in reality.

In a survey conducted this month by my nonprofit, Binaytara, we polled 30 oncology healthcare practitioners from 20 different cancer institutes around the US about ivermectin. The results were eye-opening. More than 90% of respondents stated that their cancer patients have asked about ivermectin as an adjunct to ongoing treatment or even as an alternative to standard treatment.

22 respondents expressed that they do not recommend ivermectin use for cancer treatment, while eight said they were unsure or did not have enough evidence to recommend it. Doctors shared that patients cite non-scientific sources that they find online or on social media.

These oncologists’ objections are well-justified when considering ivermectin's actual mechanism of action and approved uses. Ivermectin works by binding to specific channels in parasites, leading to muscle paralysis and ultimately their death. As oral tablets, it is FDA-approved for treating roundworm infections and river blindness. In its cream form, it is approved for treating head lice and skin conditions such as rosacea.

So, what is the sheep’s clothing that has dressed up ivermectin as a cancer cure, as often embellished by non-medical sources?

In the context of drug repurposing, scientists often investigate whether a drug approved for one condition may also be effective for another. This approach can shorten the traditional drug development timeline, making drugs available more quickly and at a lower cost. For example, semaglutide, commonly known as Ozempic, was initially approved for the treatment of type 2 diabetes. During clinical trials, researchers noticed that participants taking Ozempic also experienced weight loss. While Ozempic itself is not FDA-approved for weight loss, semaglutide under the brand name Wegovy is. Ongoing studies are still evaluating the long-term side effects of semaglutide, with several serious concerns already reported.

Following a similar drug development approach, preclinical studies published in 2020 explored a potential role for ivermectin in cancer treatment. One study suggested that Ivermectin might block cell division in colorectal cancer cells, leading to suppression of tumor growth; another suggested it could enhance the effect of chemotherapy drugs in resistant cancer cells. And these studies have been growing, exploring Ivermectin’s anti-cancer role in breast, bladder, lung, and pancreatic cancer cells.

But here’s the catch: these studies are preliminary, conducted only in lab-grown cells, and provide no evidence of clinical benefit in humans. The claim that ivermectin’s anticancer effects in the lab translate directly to effectiveness in humans is a classic fallacy of composition. The behavior displayed by cells at the unit level does not always reflect how they will act within the complexity of the human body.

This is why clinical trials exist. Despite the intriguing preclinical data, the absence of definitive, large-scale human clinical trials significantly undermines any claims that Ivermectin is a viable cancer treatment. Currently, there is a phase 1/2 clinical trial studying the side effects and best dose of Ivermectin in combination with immunotherapy in triple-negative breast cancer patients. The objective is to see whether ivermectin can enhance the effect of the immunotherapy drugs. Although the trial is set to be completed in 2026, it still needs to progress through Phase 3—where hundreds to thousands of participants are involved—and post-marketing surveillance to further confirm the drug’s effectiveness and safety.

According to the FDA, “taking large doses of ivermectin can be dangerous.” Overdose can cause nausea, vomiting, diarrhea, low blood pressure, allergic reactions, dizziness, ataxia, seizures, coma, and even death.

The misinformation about Ivermectin’s use in cancer treatment is a symptom of the broader challenges we face as oncologists in today’s climate. When prominent governmental health agencies begin endorsing alternative and unproven treatments, and funding for medical research is threatened with cuts, it only fuels public skepticism toward evidence-based medicine. This leaves people more vulnerable to scientific misinformation. The reputation of the entire medical system is at stake if this is the culture we are cultivating, one that breeds mistrust between patients and doctors.

At our medical education conferences, oncologists share that patients are echoing conspiratorial statements about cancer doctors being paid by drug companies to prescribe chemo instead of Ivermectin. “No, I am not keeping Ivermectin from you because I am getting paid by chemotherapy drug manufacturers. I am making decisions based on conclusive clinical data supported by rigorous, evidence-based research,” said one doctor.

Science is always evolving, guiding us toward what the best standard of care should be. Consensus statements from expert panels, along with recommendations from organizations like the National Comprehensive Cancer Network (NCCN) and the American Society of Clinical Oncology (ASCO), provide a general framework for physicians. Then, at each patient visit, we review the individual’s profile and develop a personalized treatment plan while keeping the patient actively involved in decisions about their care.

Building trust and navigating the doctor–patient relationship is just as critical as the treatment we provide. Ultimately, our goal as oncologists is to deliver the best possible care, guided by science and shaped by a partnership built on trust and individual care.

Author Bio

Binay Shah, MD, is a hematologist-oncologist by training and is the co-founder of Binaytara, a Bellevue-based nonprofit dedicated to reducing cancer health disparities.