Sanguinarine is a quaternary ammonium salt from the group of benzylisoquinoline alkaloids. It is extracted from some plants, including bloodroot (Sanguinaria canadensis), Mexican prickly poppy Argemone mexicana,Chelidonium majus and Macleaya cordata. It is also found in the root, stem and leaves of the opium poppy but not in the capsule.

Sanguinarine is a toxin that kills animal cells through its action on the Na⁺-K⁺-ATPase transmembrane protein.Epidemic dropsy is a disease that results from ingesting sanguinarine.

If applied to the skin, sanguinarine kills cells and may destroy tissue. In turn, the bleeding wound may produce a massive scab, called an eschar. For this reason, sanguinarine is termed an escharotic

Numerous published, pre-clinical In Vitro and In Vivo studies have demonstrated that Sanguinarine causes targeted apoptosis in human cancer cells, and recommend future development of Sanguinarine as a potential cancer treatment.A study conducted by the Case Western Reserve University in 2000 found that low doses of sanguinarine caused this apoptosis in cancerous human epidermoid carcinoma cells while little reaction from normal human skin cells was observed.