A.M. Kieley discusses online misinformation about black salve, a dangerous and ineffective “treatment” for cancer.

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The internet is ripe with a myriad of dubious health claims, with the world of “natural cures” being but one genre of the growing issue of online health misinformation. One such remedy promoted and sold online is black salve, a highly corrosive paste composed of bloodroot and zinc chloride, which health professionals do not recommend for the treatment of any condition, despite many claiming it as a cure for cancer. The general process, shared online, for how to use this supposed remedy, is to spread the paste on the suspicious area, allow it to stay on the skin for several hours, then remove the salve and wait for the results in the coming days. The paste will gradually eat through layers of skin, leaving the hopeful user to believe that the dead tissue (referred to as “eschar”) left in its place is the cancer leaving the body.

The prevailing myth among users is that the black salve only affects malignant tissue, thus sparing healthy skin from its caustic effects. Much of the discussion about black salve takes place on social media platforms like Facebook, where individuals promote its use, enthusiastically show their results, and provide instructions to others on how to use it for suspected cancers. Such online spaces seldom seek empirical evidence for health decisions and instead share a common mistrust of modern medicine, conventional modalities of treatment, and government recommendations. The pull of shared distrust, countless convincing anecdotes, and suggestions to use alternative remedies can consequently lead to pushing away evidence-based care and any physicians who react negatively to such treatments.

Photo Credit: Wikimedia commons. Image Description: An image of a bloodroot.

The choice to lean away from conventional treatments is seldom a harmless one. One unfortunate occurrence that has been identified in the literature is when the salve seemingly removes the visible tumour without addressing the full cancer, leading to metastasis and possible death. One study found that almost one-fifth of those who applied the paste to treat suspected cancers were actually targeting benign spots. Regardless of whether the user has cancer, black salve is not only ineffective—it can lead to complications like infection, skin necrosis, and irreversible cosmetic damage. But how do physicians intervene in such cases? Patients can feel that their disapproving doctor is talking down to them and trying to strip them of their bodily autonomy, which further pushes them away from evidence-based medical practices and deeper into online communities. Is there a way to avoid pushing patients away without validating dangerous health practices? How do we restore the trust in medicine that online health misinformation has helped to erode?

These two questions do not come with easy answers, but some literature has delved into possible strategies. One strategy is to engage in non-judgmental discussion that considers the factors behind beliefs in alternative treatments, like family, cultural, and religious beliefs. A systematic review on this subject added that addressing false health claims should be done in a direct and respectful fashion that avoids dismissing the believer outright, as such tactics can have the undesired effect of pushing patients away entirely. One strategy that could be used in this type of discussion is the LEARN model: “Listen, Explain, Acknowledge, Recommend, and Negotiate,” which employs techniques such as sympathetic listening and openly discussing the areas where the parties involved agree and disagree.

It is all too easy to read the scores of Facebook posts about black salve and come away believing that these health beliefs are the result of foolishness. However, it is important to consider that group members feel a sense of community in the online spaces where these claims are spread. Anecdotal stories rife with emotion come across as convincing evidence, especially when the reader is already skeptical about medical practice to the extent that they would seek out such online communities to begin with. Once a piece of online health misinformation has reached a person and convinced them of a falsehood, correcting the false claim with factual information is difficult—it is much easier to convince someone of something false than to successfully correct the misinformation. For health professionals, this reality can easily lead to a pessimistic outlook on combating health misinformation. Nonetheless, it is essential to continue conceptualizing strategies that not only keep the public safe from harm but also encourage media literacy and critical thinking. In the absence of an easy cure for health misinformation, a compassionate and understanding approach must be taken when discussing the questionable effectiveness of proclaimed natural cures like black salve.

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A.M. Kieley is a PhD student in Community Health at Memorial University of Newfoundland, Faculty of Medicine. They can be found on Bluesky here.

This commentary was originally written in the context of a graduate seminar on health misinformation and lies.