Black salve is a paste for external use made from a variable mixture of herbal and non-herbal ingredients. It usually contains bloodroot and/or chaparral and/or zinc chloride which are all ingredients that render the products corrosive. This means black salve destroys living cells that come in contact with it.
Black salve is said to originate from native American tribes who used the paste as a treatment for various conditions. It was adopted by conventional medicine during the Victorian era as a treatment for a range of skin problems, including skin cancers. When effective treatments became available, it became obsolete.
Black salve was recently re-discovered by some practitioners of so-called alternative medicine (SCAM) who now recommend it as a natural treatment for various skin conditions, including cancer. Black salve is readily available, for instance, via the Internet. Several national regulators have issued warnings to consumers not to use it. Consumers have little means of telling what is the nature, quality or strength of the black salve they might be purchasing.
No compelling evidence exists that black salve is efficacious for any condition, especially not for any type of skin cancer. Rigorous clinical trials testing its efficacy are not available. A recent review of the published evidence concluded as follows: Black salve is not a natural therapy. It contains significant concentrations of synthetic chemicals. Black salve does not appear to possess tumour specificity with in vitro and in vivo evidence indicating normal cell toxicity. Black salve does appear to cure some skin cancers, although the cure rate for this therapy is currently unknown. The use of black salve should be restricted to clinical research in low risk malignancies located at low risk sites until a better understanding of its efficacy and toxicity is developed. Where a therapy capable of harm is already being used by patients, it is ethically irresponsible not to study and analyse its effects. Although cautionary tales are valuable, black salve research needs to move beyond the case study and into the carefully designed clinical trial arena. Only then can patients be properly informed of its true benefits and hazards.
Due to its erosive nature, black salve burns away the tissue with which it comes into contact. Numerous case reports of the resulting deformations have been published., Many horrendous pictures of patients maimed by their use of black salve are available on the Internet and give a dramatic impression of the harm caused. Black salve is unquestionably a treatment that can cause considerable damage and should be regarded as unsafe. One paper concluded that it is vital that members of the public are aware of the potential effects and toxicity of commercial salve products.
In conclusion, black salve is not of proven efficacy as a treatment of any condition. It is well documented to cause much harm. Its use should be discouraged. Practitioners who employ or recommend it are, in my view, irresponsible to the extreme.
 Croaker A, King GJ, Pyne JH, Anoopkumar-Dukie S, Liu L. A Review of Black Salve: Cancer Specificity, Cure, and Cosmesis. Evid Based Complement Alternat Med. 2017;2017:9184034. doi:10.1155/2017/9184034
 Ong NC, Sham E, Adams BM. Use of unlicensed black salve for cutaneous malignancy. Med J Aust. 2014;200(6):314. doi:10.5694/mja14.00041
 Saltzberg F, Barron G, Fenske N. Deforming self-treatment with herbal “black salve”. Dermatol Surg. 2009;35(7):1152-1154. doi:10.1111/j.1524-4725.2009.01206.x
 Lim A. Black salve treatment of skin cancer: a review. J Dermatolog Treat. 2018;29(4):388-392. doi:10.1080/09546634.2017.1395795