Medically reviewed by Sharif Alijla, MD. Last reviewed July 2026.
Black salve is a corrosive paste, sold as a natural skin cancer cure, that destroys living tissue without distinguishing tumour from healthy skin. The FDA tells consumers not to use it. It has caused permanent disfigurement, has left cancer growing beneath apparently healed skin, and the agency is aware of at least one death where someone used a corrosive salve instead of proven treatment. In a large Australian analysis, 34.2% of black salve treated areas still contained cancer. Meanwhile the skin cancers people use it on are among the most curable cancers there are, with surgical cure rates above 95%. Here is what it is and why it fails.
What Black Salve Is
It is an escharotic, meaning a caustic paste that kills tissue and produces an eschar, a thick black scab, which eventually detaches and leaves an open ulcer.
The two main ingredients are bloodroot (Sanguinaria canadensis), which contains the alkaloid sanguinarine, and zinc chloride, an industrial chemical that in some preparations is the largest ingredient by weight. Many products also contain DMSO to drive penetration.
It is sold under many names, including Cansema, Skinprov, drawing salve, red salve, Indian Herb, Black Drawing Ointment, and compound X.
The ānatural remedyā framing does not survive contact with the ingredient list. As the most thorough review of the subject puts it: āBlack salve is not a natural therapy. It contains significant concentrations of synthetic chemicals.ā
What the FDA Says
The FDA issued a consumer update on 13 October 2020 titled āDo Not Use: Black Salve is Dangerous and Called by Many Names.ā Its position:
Do not use topical products containing sanguinarine, bloodroot, or zinc chloride, including when they appear as inactive ingredients. These products are not FDA approved to treat or cure any skin condition, and specifically not skin cancer. They can kill skin tissue, causing pain, permanent scarring, disfigurement, and infection. Use on skin cancer lesions can lead to delayed diagnosis and cancer progression. The FDA has received 24 adverse event reports, 15 of them in the preceding five years, and is aware of at least one death.
The FDA has also issued warning letters to sellers. One 2017 letter quotes the sellerās own marketing back at it, including the claim that the product āattacks and destroys abnormal tissues and dose not harm the surrounding healthy tissue.ā That is precisely the claim the scientific evidence refutes.
Australiaās Therapeutic Goods Administration issued a comparable alert in 2012, stating it is not aware of any credible scientific evidence that these products treat or cure cancer.
Why the Central Claim Is False
Everything about black salve marketing rests on the idea that it targets cancer and spares healthy tissue. It does not.
In laboratory studies, the apparent selectivity disappears as concentration rises. At one dose sanguinarine killed 60% of carcinoma cells against 10.8% of normal skin cells, but at a higher dose the figures were 65% against 38.3%. Other work found sanguinarine more toxic to normal skin fibroblasts than to the cancer cell line.
In patients, examination of a detached eschar found it contained both malignant and normal tissue.
The historical evidence is decisive. In 1941, Dr Frederic Mohs found that a zinc chloride solution killed benign and malignant tissue alike while preserving microscopic structure. That indiscriminate action is the entire point of Mohs paste. It kills everything and preserves the architecture so a pathologist can map the margins. Seventy-five years of Mohs slides attest to it. Mohs applied his paste to a gangrenous toe and fixed the whole toe for amputation. Tissue destruction two centimetres deep can occur in 24 hours, and cartilage is penetrated especially fast, which is why noses are destroyed so readily.
Mohs patented his paste specifically to stop untrained people using it blindly.
The Trap: It Looks Like It Worked
This is the mechanism of the harm and the reason testimonials are so persuasive.
The eschar forms, turns black, and detaches, leaving a crater. To the person using it, this reads unmistakably as the cancer coming out. It is a compelling performance of a cure.
But the depth of the effect is unknown and uncontrolled, and malignancy can persist beneath the scar tissue and spread deeper before becoming visible again. In the Australian study of 409 patients treating 475 lesions across five states, 34.2% of treated areas contained persisting cancer. That study also found black salve caused necrosis of normal tissue when used on benign lesions, directly refuting the specificity claim. Roughly 18% of the lesions treated were benign, meaning healthy tissue was destroyed for no reason at all.
The Documented Harm
A review of pathology-confirmed cases found 19 skin cancers in 15 people. Nine of the 19 were clear failures: five cancers persisted and four metastasised.
Specific outcomes from the literature:
A patient whose nose cancer appeared to resolve had it recur, invade the upper jaw requiring partial removal, spread to lymph nodes, and died of metastatic basal cell carcinoma. Basal cell carcinoma almost never spreads. That it did here is a measure of how long it was left.
Both documented patients who used black salve on melanoma developed metastatic disease. One had a 0.6 mm melanoma on the calf, which carries an expected 92.2% twelve-year survival with standard surgery. A highly curable cancer became a metastatic one.
One patient presented with a 10 cm scalp squamous cell carcinoma with nerve invasion and lymph node spread.
Salvage of black salve failures has required eight-stage and ten-stage Mohs surgery.
All five recorded disfigurement cases involved the nose. Two patients lost part of the nostril, one had a hole through the nostril requiring flap repair, and two women had most of the nose destroyed, requiring multiple reconstructive operations.
Benign lesions have also been destroyed. A biopsy-proven ordinary mole on a womanās thigh became a 5 cm inflamed plaque. A 29-year-old man needed three scar revision surgeries.
On cosmetic outcome, among 25 assessable lesions, only two, or 8%, were rated fair to good. Fifty-two percent scarred, 8% formed keloids, and 20% resulted in deformity. For comparison, 87% of standard excision patients and 93% of Mohs patients rate their result as good or satisfactory. Black salve is marketed as cosmetically superior to surgery. It is the opposite. Ulcers can take up to two years to heal.
The Dose Is Unknown
Worth stating on its own. Black salve has been chemically analysed in the published literature only once, from a single sample, without quantitative results. Nobody knows what concentration any given jar contains. Bloodroot rhizomes vary up to fifteenfold in sanguinarine content. Mohs paste is standardised at 45.2% zinc chloride; black salve concentration has never been reported, and Mohs himself knew an extra millimetre of thickness could mean significant extra destruction.
So: an unlabelled product of unknown strength, applied by an untrained person, to an undiagnosed lesion, often on the face.
It Also Makes Later Diagnosis Harder
Beyond delay, black salve degrades the pathology that follows. In one series of 16 treated lesions, pathologists needed special staining in 44% of cases because the salve produced changes mimicking malignancy.
What Real Treatment Looks Like
The first step is always a biopsy. No treatment decision can be made without knowing what the lesion is. Black salve users skip this entirely, which is how 18% of Australian users ended up destroying tissue over benign lesions.
| Treatment | Outcome |
|---|---|
| Mohs surgery, primary basal cell carcinoma | 99.5% cure |
| Standard excision, primary basal cell carcinoma | 95.2% cure |
| Mohs surgery, primary squamous cell carcinoma | 97.4% recurrence-free at 5 years |
| Standard excision, primary squamous cell carcinoma | 94.6% recurrence-free at 5 years |
Mohs micrographic surgery removes tissue in stages with margins checked during the procedure, conserving the maximum healthy tissue. It is the standard for higher-risk cancers and for the face, nose, ears, and eyelids. This is the treatment black salve users are declining.
Prescription topical treatments exist for selected low-risk lesions, including imiquimod and 5-fluorouracil. The contrast is instructive: these are prescribed after a biopsy, at a known concentration, for defined lesion types, with follow-up. Black salve imitates the format of a topical treatment while lacking every one of those safeguards.
Other options include curettage for low-risk lesions, photodynamic therapy, radiotherapy where surgery is not suitable, and systemic therapy for advanced disease. For melanoma, surgical excision with clear margins is first-line at any thickness.
Being Precise About the Claim
One point of honesty, because overstating the case would undermine it. The most thorough review of black salve does not conclude that it never destroys cancer. It concludes that black salve does appear to cure some skin cancers, but that the cure rate is unknown, that it lacks tumour specificity, and that its use should be restricted to clinical research. There has never been a randomised trial in the 150-year history of its use.
That is more than enough. The case against black salve does not need exaggeration: it destroys healthy tissue, its dose is uncontrolled, a third of treated areas still contained cancer, it has caused metastatic disease and at least one death, and the alternative cures more than 95% of cases while leaving a better scar.
If You Have Used It
See a dermatologist and say clearly what you applied and when. Apparently healed skin does not mean the cancer is gone, and the site may need biopsy or excision. Bring any remaining product or packaging. Nobody will be judging you.
Black Salve FAQs
Does black salve cure skin cancer?
It sometimes destroys cancer, but the cure rate is unknown and has never been tested in a trial. In a large Australian analysis 34.2% of treated areas still contained cancer. It does not distinguish tumour from healthy tissue.
Is black salve FDA approved?
No. The FDA issued a consumer warning in October 2020 telling people not to use it, and has sent warning letters to sellers marketing it as a cancer treatment.
Why is black salve dangerous?
It destroys living tissue indiscriminately, at an unknown concentration, often to a depth of centimetres. It can leave cancer growing under an apparently healed scab while the visible scab detaching looks like a cure. Documented outcomes include nasal destruction, metastatic disease, and death.
Is black salve natural?
No. Zinc chloride is a synthetic industrial chemical and in some preparations is the main ingredient by weight.
What should I use instead?
Get a biopsy first, then treatment appropriate to the diagnosis. Mohs surgery cures 99.5% of primary basal cell carcinomas and standard excision 95.2%, with far better cosmetic results than black salve.
I already used black salve. What now?
See a dermatologist promptly and tell them what you used. Healed-looking skin does not mean the cancer has gone, and the area may need biopsy or removal.
