# Black salve and other escharotic pastes

Source: https://onco.cc/technologies/black-salve-escharotics/  
OnCo record `black-salve-escharotics` (Technology). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Black salve is a corrosive paste containing bloodroot and zinc chloride sold online to 'draw out' skin cancers. It burns whatever it touches, leaves disfiguring scars, does not reliably remove the cancer, and has let melanomas spread while people believed they were cured.

## Summary

Escharotic pastes (black salve, Cansema, bloodroot paste) contain sanguinarine from Sanguinaria canadensis with zinc chloride and destroy tissue non-selectively, forming an eschar that falls away. They have no ability to distinguish tumour from normal skin, no margin control and no histology, so residual tumour is common and the resulting wounds are large and disfiguring; case series document melanoma progression to metastasis and loss of noses and ears after self-treatment. The FDA lists black salve among fake cancer cures and has issued warning letters, and it is illegal to market for cancer in the US and Australia. Basal and squamous cell skin cancers are among the most curable cancers with surgery, topical prescription agents or radiotherapy, which is why this product does so much avoidable harm.

## Fields

- Kind: Technology
- Status: negative
- Last checked: 2026-09-10
- Tags: complementary; supportive-care; evidence:harm
- Principle: Non-selective chemical necrosis of skin and underlying tissue; the sanguinarine has cytotoxic activity but no tumour selectivity.
- Strengths: None as a treatment; a clear counselling example
- Limitations: Disfiguring burns and scars; Incomplete tumour removal, delayed diagnosis of melanoma; Illegal to market for cancer

## Notes

- Escharotic pastes are sold as an alternative to skin cancer surgery and are the destructive treatment with no evidence at all behind it. Unlike curettage, cryotherapy and photodynamic therapy, each of which has randomised trials quantifying what it costs in cure rate, black salve has none: it destroys tissue without control of depth or margin, leaves a scar that hides residual tumour from examination, and has been reported to let melanomas spread under it. The comparison with the treatments in the same row is the argument: a patient who wants to avoid an operation has four options that have been measured, and this is not one of them.

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Black_salve
- FDA: products claiming to 'cure' cancer are a cruel deception: https://www.fda.gov/consumers/consumer-updates/products-claiming-cure-cancer-are-cruel-deception

## Connected records

- terms: [Creams, light and cold for basal cell carcinoma](https://onco.cc/terms/topical-and-destructive-treatment-bcc/), [The margin in skin cancer surgery](https://onco.cc/terms/surgical-margins-keratinocyte-cancer/)
- cancers: [Basal cell carcinoma](https://onco.cc/cancers/basal-cell-carcinoma/), [Cutaneous squamous cell carcinoma](https://onco.cc/cancers/cutaneous-scc/), [Melanoma](https://onco.cc/cancers/melanoma/), [Skin cancer (all types)](https://onco.cc/cancers/skin-cancer/)
- fronts: [Supportive Care & Survivorship](https://onco.cc/fronts/supportive-care/)
- technologies: [Alternative medicine used instead of standard treatment](https://onco.cc/technologies/alternative-medicine-instead-of-treatment/)
- bottlenecks: [Misinformation and unproven therapies](https://onco.cc/bottlenecks/b-misinformation/)

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