The major constituents in plantain are mucilage, iridoid glycosides (particularly aucubin), and tannins. Together these constituents are thought to give plantain mild anti-inflammatory, antimicrobial, antihemorrhagic, and expectorant actions. Plantain is approved by the German Commission E for internal use to ease coughs and mucous membrane irritation associated with upper respiratory tract infections as well as topical use for skin inflammations. Two Bulgarian clinical trials have suggested that plantain may be effective in the treatment of chronic bronchitis. Insufficient details were provided in these reports to determine the quality of the trials or their findings. Although plantain was thought to possess diuretic properties, one double-blind trial failed to show any diuretic effect for this plant. A preliminary trial found that topical use of a plantain ointment (10% ground plantain in a base of petroleum jelly) was helpful as part of the treatment of people with impetigo and ecthyma, two inflammatory skin disorders. Insufficient details were provided in this report, however, to determine the quality of the study or its findings.