According to traditional Chinese medicine, Rehmannia has the functions of warming the lungs, lowering the qi, eliminating phlegm and stopping cough. It has good therapeutic efficacy for new and prolonged cough, phlegm, asthma, coughing up phlegm, coughing up blood and so on. It can treat wind-cold cough, asthma, exhaustion, coughing up pus and blood, paralysis of the throat, and dysuria. There is a certain antibacterial effect, in vitro for Escherichia coli, dysentery bacillus, aspergillus, typhoid fever, paratyphoid fever bacillus, Pseudomonas aeruginosa and Vibrio cholerae, gram-negative bacteria have a certain inhibitory effect. And it can also resist pathogenic fungi. When using the drug, those with solid heat are prohibited.