Salves that contain corrosive ingredients, including “black salve” and a number of other names, are dangerous and can be life-threatening.
You may have seen websites selling certain salves or creams (commonly known as “black salve”) claiming to treat or cure cancer, boils, moles and skin tags (benign, or non-cancerous, growths of the skin).
These claims are false. Salve products containing corrosive ingredients, including black salve, are dangerous and are not approved by the U.S. Food and Drug Administration (FDA) to treat or cure any skin condition, particularly not skin cancer. Specifically, the FDA is warning consumers not to use any salves or other topically applied products that list any of the following potentially dangerous ingredients: sanguinarine, Sanguinaria canadensis, or bloodroot, alone or in combination with zinc chloride.
Although not all salves are dangerous, topically applied products with the above ingredients can destroy the skin and result in permanent disfigurement, tissue necrosis (death of cells in living tissue), and can result in infection. Furthermore, using salve products such as black salve for serious conditions like skin cancer can result in delayed cancer diagnosis and cancer progression.

Read the full report here.
As published by the FDA on HealthyExaminer.com