Cannabis – Used as a recreational and medicinal drug. Chemicals derived from cannabis have been extensively researched for potential anti-cancer effect and while there has been much laboratory work, claims that cannabis has been proven to cure cancer are – according to Cancer Research UK – "highly misleading".[57] The US National Cancer Institute notes "Cannabis is not approved by the FDA for the treatment of any cancer-related symptom or side effect of cancer therapy."[58] Cansema (also called black salve) – a type of paste or poultice often promoted as a cancer cure, especially for skin cancer.