Black salve
Also called: bloodroot paste, escharotic, drawing salve, Cansema.
Last reviewed 2026-09-16. How this works.
When to call your team
Contact your care team the same day if you notice:
- a wound or scab that is not healing
- the area becoming more painful, swollen or hot
- spreading redness around the edge
- a new lump, or any change at the edge of a scar
- feeling feverish or generally unwell
These are reasons to make a phone call. They are not a diagnosis, and this page cannot tell you what is causing them. If a salve has been used on a lesion, telling your team is the only way anyone can find out what is underneath it.12
These are reasons to make contact, not a diagnosis. Whatever you are taking or thinking of taking, the people treating you can only weigh it if they know about it.
This block is about what to watch for, and it is not all this page holds: what has been recorded about harm is below. Nothing in this block is an all-clear for a question it does not mention.
Treating skin cancer Grade X
Documented harm, with no benefit to weigh against it.
Harm has been recorded in people for this claim. The grade measures how strong the evidence for benefit is; it says nothing about the harm, and the two are read from different parts of this page.
This paste burns away skin, and cancer has been found still growing under the scar it leaves.
It burns. In the dish, a normal cell died at a lower concentration than any cancer line.
The harm
The active compound is sanguinarine, from bloodroot. In the laboratory table behind this entry, the concentration that killed half the cells was lowest for a normal gingival fibroblast, lower than for every cancer line tested, including the squamous cell carcinoma line that represents the kind of skin cancer the product is sold to treat. The normal keratinocyte was the hardest of all to kill. The product is described as selective for cancer. In the dish, selectivity is not what the numbers show.1
The review's own conclusion is that black salve is likely to possess normal tissue toxicity, with some cancer cell lines relatively resistant to its effects, and that this may explain the case reports of excessive scarring, deformity and treatment failure.1
A national retrospective series of Australian pathology specimens covering five years found cancer still present in treated lesions. Where a benign lesion had been treated instead, the surrounding normal skin was necrotic, ulcerated or scarred. The authors record that a persisting malignancy places a person at considerable risk of spread and of death, and that this has already been documented to happen after black salve use.2
There is no consistent product. Measured sanguinarine content varied between manufacturers by a factor of twelve and a half thousand, with the strongest preparations far above the concentration needed to kill a normal human skin cell. No two applications are the same thing.2
Sanguinarine has itself been reviewed for cancer-causing potential. Its structure resembles known carcinogens, it inserts itself into DNA, and it produces the kind of cellular stress that leaves genetic damage behind. The review is careful to say that laboratory and animal results conflict and that the question is not settled. It is not a finding of harm. It is the absence of reassurance, in the compound being applied to treat a cancer.3
The claim
Advocates describe black salve as a paste that draws a skin cancer out of the body, leaving a dark plug of dead tissue that separates and takes the cancer with it. The plug is offered as proof that it worked.
What it does
It is an escharotic, meaning it destroys the tissue it touches and leaves a thick dark scab called an eschar. That is the whole mechanism. It does not distinguish between tissue that is cancer and tissue that is not, and the plug that separates is destroyed skin rather than a removed tumour.1
The evidence
No study in people has tested whether black salve removes a skin cancer. What exists instead is laboratory work on the compound and pathology from people it was used on, and both point the same way.12
What is absent
No completed clinical trial of black salve exists, and the authors of the pathology series state that running one would be ethically unacceptable given the cancer-causing potential of sanguinarine. This is an absence that is not going to be filled.
Scope: any skin cancer, any endpoint.
Established by published review, Croaker, Liu and Myers 2023, checked 2026-09-16. Result: the authors record that a clinical trial would be ethically unacceptable.2
No study in people has reported that black salve removes a skin cancer. The harm on this page has nothing on the other side of the scale to be weighed against it.
Scope: any skin cancer, any endpoint.
Established by published review, Croaker et al. 2017 and Croaker, Liu and Myers 2023, checked 2026-09-16. Result: neither review reports a human study of benefit; both report the opposite.12
What to ask
If a black salve product has been used on a skin lesion, what would you need to examine to know whether anything is still there underneath the scar?
The dish-to-person gap
Black salve is applied to the skin to destroy tissue where it is put. The question the dish-to-person gap answers, whether enough of a compound reaches the body to matter, is not the question this product raises.
Interactions
This is a caustic applied to the skin rather than a compound taken into the body, so the treatment-class interaction matrix does not apply to it. The question it raises is about the skin it was applied to, and that belongs to a doctor who can look at it.
The whole interaction list, and how to turn it into a pharmacy review request.
Find a trial instead
There is no trial link to offer, and the reason is recorded in the evidence on this page: the authors of the pathology series state that a clinical trial would be ethically unacceptable. The redirect this entry needs is to a doctor who can examine the skin.
References
Croaker A, King GJ, Pyne JH, Anoopkumar-Dukie S, Liu L. A review of black salve: cancer specificity, cure, and cosmesis. Evidence-Based Complementary and Alternative Medicine 2017 Jan 26;2017:9184034.
doi:10.1155/2017/9184034 · PubMed 28246541 · PMC5299188
How this was reached: transcribed from chapter note, via docs/CHAPTER-NOTES.json, chapter 18 note 15.
Held against this source and not confirmed:
52 percent scarring
Frequently quoted and attributed to this paper. Not present in the sections of it that were read. Not used anywhere in this record.
20 percent deformity
Frequently quoted and attributed to this paper. Not present in the sections of it that were read. Not used anywhere in this record.
Croaker A, Liu L, Myers SP. Persisting cancer in black salve treated skin lesions: results of a large 5 year retrospective analysis of Australian histopathology specimens. Integrative Cancer Therapies 2023.
How this was reached: transcribed from chapter note, via docs/CHAPTER-NOTES.json, chapter 18 note 16.
Carcinogenic potential of sanguinarine, a phytochemical used in therapeutic black salve and mouthwash. Mutation Research: Reviews in Mutation Research, 2017.
doi:10.1016/j.mrrev.2017.05.002
How this was reached: transcribed from chapter note, via docs/CHAPTER-NOTES.json, chapter 18 note 17.