Four Qi refers to the four different properties of traditional Chinese medicine: cold, hot, warm, and cool. Cold Chinese medicine has the effects of clearing heat, purging fire, detoxifying and reducing swelling, and is suitable for heat related diseases such as gypsum and Zhimu; Hot traditional Chinese medicine has the functions of warming the middle and dispersing cold, aiding yang and tonifying qi, and is suitable for cold diseases such as aconite and cinnamon; Warm traditional Chinese medicine has the functions of warming and dispersing cold, tonifying qi and blood, and is suitable for cold diseases such as Astragalus membranaceus and Codonopsis pilosula; Cool traditional Chinese medicine has the functions of clearing heat and detoxifying, purging fire and nourishing yin, and is suitable for heat related diseases such as honeysuckle and forsythia.
四气是指中药具有寒、热、温、凉四种不同的性质。寒性中药具有清热泻火、解毒消肿等作用，适用于热性病症，如石膏、知母等；热性中药具有温中散寒、助阳益气等作用，适用于寒性病症，如附子、肉桂等；温性中药具有温中散寒、补益气血等作用，适用于寒性病症，如黄芪、党参等；凉性中药具有清热解毒、泻火养阴等作用，适用于热性病症，如金银花、连翘等。