Blue flag was widely used by Native Americans, and was official in the U.S. Pharmacopeia from 1820 to 1895. Its main uses were for impetigo, eczema and psoriasis. It is also helpful in liver-related constipation and biliousness. That is, it seems to help both skin and digestive problems by helping the liver and gall bladder with their detoxifying and fat-processing function. Used as a strong decoction, extract and tincture. Blue flag increases urination and bile production, and has a mild laxative effect. Blue flag formulations relieve pain of the liver and gall bladder, which may occur after excessive ingestion of fatty foods, alcohol or coffee. The combination of cleansing actions makes it a useful herb for chronic skin diseases such as acne and eczema, especially where gall bladder problems or constipation contribute to the problem. In small doses, blue flag relieves nausea and vomiting. Blue flag contains triterpenoids, salicylic and isophthalic acids, a very small amount of volatile oil made up of irone, in particular ? alpha, beta and gamma irone, starch, resin, an oleoresin, tannins, and isoflavonoids. Grieve’s classic ‘A Modern Herbal’: ‘The root is an official drug of the United States Pharmacopoeia and is the source of the Iridin or Irisin of commerce, a powdered extractive, bitter, nauseous and acrid, with diuretic and aperient properties.’ ‘Iridin acts powerfully on the liver, but, from its milder action on the bowels, is preferable to podophyllin.’ ‘The fresh Iris is quite acrid and if employed internally produces nausea, vomiting, purging and colicky pains. The dried root is less acrid and is employed as an emetic, diuretic and cathartic. ‘The oleoresin in the root is purgative to the liver, and useful in bilious sickness in small doses.’ ‘It is chiefly used for its alterative properties, being a useful purgative in disorders of the liver and duodenum, and is an ingredient of many compounds for purifying the blood. It acts as a stimulant to the liver and intestinal glands and is used in constipation and biliousness, and is believed by some to be a hepatic stimulant second only to podophyllin, but if given in full doses it may occasion considerable nausea and severe prostration.’ ‘Its chief use is for syphilis and some forms of low-grade scrofula and skin affection. It is also valuable in dropsy.’ ‘It is said to have been used by the southern North American Indians as a cathartic and emetic.’ ‘Preparations and Dosages: Powdered root, as a cathartic, 20 grains. Irisin, 1 to 3 grains. Solid extract, 10 to 15 grains. Fluid extract, ½ to 1 drachm. Tincture, 1 to 3 drachms.’ King’s 1898 Dispensatory: ‘Physiologically, iris acts upon the gastro-intestinal canal, and the glandular and nervous systems. It powerfully excites the biliary, salivary, and pancreatic secretions. Upon the gastro-intestinal tract it acts violently, causing acid vomiting, frequent, hydragogue catharsis, with
