Root used as a condiment Root tea weakly diuretic, antiseptic, and expectorant; used for bronchitis, coughs, bronchial catarrh, calculus (dental plaque). Root poultice used for rheumatism, respiratory congestion. Few things are better at opening the sinuses than too large a bite of pungent horseradish sauce. Science confirms plant is antibiotic against gram-negative and gram-positive bacteria, pathogenic fungi. Experimentally, it has antitumor activity, as Science has come to expect from the mustard family. Warning: Large amounts may irritate digestive system. Plant tops are a fatal poison to livestock. External use may cause skin blisters.