As-Suyuti in "Medicine of the Prophet" said, " Shatarah — Fumitory [has the quality of] heat and dryness. Its special property is to cleanse the blood and set flowing inflamed humours. And in a similar manner it is beneficial for scabs and itch. Said Rhazes: Fumitory is a solvent which makes to flow the inflamed humours and is also good for scabs and pruritus. The dose for each of these is from four to seven drachms. I maintain that this is the best rectifier of all purges, but it is essential to add olive oil and sugar. “
Menzies-Trull in "The Herbalist's Prescriber" classifies fumitory as a choleretic (something that increases bile secretion from the liver and increases solids secreted) and says it’s for external use for conjunctivitis.
David Hoffman in “The New Holistic Herbal” says it’s a diuretic, laxative and alterative and, “has a long history of use in the treatment of skin problems such as eczema and acne. Its action is probably due to a general cleansing mediated via the kidneys and liver.
Michael Howard in Traditional Folk Remedies warns that fumitory is “poisonous” and should only be used "under the direction of a medical herbalist."
Traditional Chinese Medicine calls it Yao Yong Qiu Guo Guo Zi Jin and uses it for skin diseases.
Image: By Luis Nunes Alberto (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0) or GFDL (http://www.gnu.org/copyleft/fdl.html)], via Wikimedia Commons