Black salve is a controversial topical paste promoted primarily in alternative medicine circles for treating skin lesions. Its usage is debated because its purported benefits are not supported by scientific evidence, and its application carries serious health risks. This article explores the claimed uses of black salve and details the medical consensus regarding its composition, mechanism, and safety.
Composition and Historical Context
Black salve is a paste-like substance with a variable, unregulated composition. Most formulations contain two primary active ingredients: an extract from the Bloodroot plant (Sanguinaria canadensis), which contains the alkaloid sanguinarine, and the synthetic corrosive compound zinc chloride (\(\text{ZnCl}_2\)). Zinc chloride is often the most concentrated ingredient in the mixture.
Historically, escharotic agents, which are chemicals that destroy living tissue, were used in folk medicine and early dermatology. The use of bloodroot and similar compounds dates back centuries. In the 20th century, a paste containing zinc chloride and bloodroot was notably used as a tissue fixative in a predecessor to modern Mohs surgery.
The modern resurgence of black salve promotes it under claims of being a “natural” therapy. This characterization is misleading because the zinc chloride component is a synthetic chemical. This paste is often sold online under various names, including Cansema, drawing salve, or red salve.
The Primary Claimed Application
The primary use promoted by vendors and proponents of black salve is as an escharotic agent for managing skin lesions, particularly those suspected to be cancerous. Proponents claim that the salve can effectively treat common skin cancers such as basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and even malignant melanoma. It is also promoted for removing benign growths like moles and skin tags.
The central claim is that the paste can selectively target and “draw out” the diseased tissue, supposedly leaving healthy skin unharmed. This process results in the formation of a thick, dark, scabby mass known as an eschar, which eventually sloughs off the skin. The belief is that once the eschar falls away, the underlying malignancy has been completely eliminated. However, these claims are not supported by scientific or clinical evidence, and the product is not approved by major health authorities for treating any skin condition.
How Black Salve Works (The Caustic Mechanism)
The mechanism by which black salve affects skin tissue is indiscriminate chemical destruction, not selective targeting. The caustic action is primarily due to the high concentration of zinc chloride, a highly reactive substance that injures living tissue. This compound causes tissue necrosis, which is the death of cells, through chemical destruction or by inducing significant inflammation.
When applied to the skin, the salve acts as a chemical burn, destroying any tissue it contacts, whether healthy or cancerous. The highly destructive effect leads to the formation of a painful, black, ulcerated wound that becomes the eschar. The salve does not possess the ability to distinguish between a malignant tumor and the surrounding normal skin structure. This indiscriminate cytotoxicity is confirmed by studies showing that the active ingredients are toxic to both malignant and normal skin cells.
The application of black salve is typically associated with intense pain and a severe burning sensation as the corrosive ingredients penetrate the skin. The resulting eschar is essentially a mass of dead, necrotic tissue that has been chemically fixed by the caustic agents. While the eschar may eventually detach, the underlying wound is a deep, chemical injury that can extend far beyond the visible borders of the original lesion.
Severe Health Risks and Permanent Damage
The use of black salve carries severe and medically documented health risks, leading to strong warnings from major health organizations, including the U.S. Food and Drug Administration (FDA). The most immediate and common consequence is permanent disfigurement due to extensive scarring. Because the caustic agents destroy tissue indiscriminately and deeply, the resulting wounds often require complex medical intervention, including reconstructive plastic surgery.
A significant danger is the risk of misdiagnosis and delayed medical treatment for serious conditions. Individuals often use the salve on suspected skin cancers, which can lead to the destruction of the superficial layer of a tumor while leaving the deeper cancerous cells intact. The resulting scar tissue can hide the remaining malignancy, allowing the cancer to continue growing and potentially metastasize to other parts of the body.
Using black salve can also lead to secondary complications, such as infection, including cellulitis, in the open, necrotic wound it creates. Health authorities prohibit the marketing of black salve products for cancer treatment because they are not approved as a safe or effective therapy for any condition.