Elymus repens extract it valued by herbalists for its mucilage rich rhizome. A tea made from the roots is useful for treating urinary infections because of the herb's broad antibiotic, and diuretic properties. One of the chemical constituents, agropyrone, has been shown to have strong antibiotic properties. Couch grass tea will also soothe and coat an inflamed sore throat, and helps clear phlegm. The herb contains mucilage that helps to clear congestion while it coats the throat.