The effective components can be decocted and taken. Mahuang Decoction is composed of Herba Ephedrae, Ramulus Cinnamomi, Semen Armeniacae Amarum and Radix Glycyrrhizae Preparata, and has the effects of sweating, relieving exterior syndrome, dispersing lung qi and relieving asthma. The reason for soaking in cold water before cooking is that the effective components can be better decocted out, which can be used to treat the exterior syndrome of exogenous wind-cold inside and outside the body, and the clinical manifestations are aversion to cold, fever, head and body pain and so on.