Although previous studies have suggested the long-term use of dental products containing sanguinarine is safe,⁶ a recent report suggests that use of dental preparations containing blood root may be associated with leukoplakia—a condition characterized by white spots or patches in the mouth that is thought to be precancerous.⁷ Only small amounts of bloodroot should be taken internally, since amounts as small as 1 ml (approximately 2030 drops) of tincture or 1 gram (approximately 1/30th ounce) can cause nausea and vomiting.^{8, 9}

Long-term use or overdose of bloodroot can also cause stomach pain, diarrhea, visual changes, paralysis, fainting, and collapse.¹⁰ Long-term oral intake of sanguinarine-contaminated cooking oils has been linked in India to glaucoma, edema, heart disease, miscarriage, and diarrhea.¹¹ The sanguinarine in these cases came from plants other than bloodroot. Nevertheless, bloodroot should not be used long term. The plant is unsafe for use in children and should not be used by pregnant or lactating women.

Recently the practice of applying ointments containing bloodroot, such as the so-called “black salve,” has been promoted for treatment of skin and other types of cancer.¹² These ointments have never been tested in clinical studies, so their efficacy for treating cancer is unknown. They can cause severe pain, burns, and damage to healthy skin. It is imperative to seek professional diagnosis and treatment for all forms of cancer.