In Traditional Chinese Medicine (TCM), Qing Dai belongs to the 'Herbs that clear Heat and relieve Toxicity' category. Herbs in this category are used to clear inflammatory and infectious conditions, referred to as 'Internal Heat' in TCM. This is why most of the herbs in this category will have both antibacterial and antiviral properties. In TCM one has too much 'Internal Heat' in their body as a result of a deficiency of 'Yin' (which is Cold in nature, see our explanation on Yin and Yang) or, more commonly, an Excess of Yang (Hot in nature). Herbs that clear Heat and relieve Toxicity treat the latter while, at the same time, removing infectious toxins from the body. As such they tend to be Cold or Neutral in nature.
As suggested by its category Qing Dai is Cold in nature. This means that Qing Dai typically helps people who have too much 'Heat' in their body. Balance between Yin and Yang is a key health concept in TCM. Those who have too much Heat in their body are said to either have a Yang Excess (because Yang is Hot in nature) or a Yin deficiency (Yin is Cold in Nature). Depending on your condition Qing Dai can help restore a harmonious balance between Yin and Yang.
Qing Dai also tastes Salty. The so-called 'Five Phases' theory in Chinese Medicine states that the taste of TCM ingredients is a key determinant of their action in the body. Salty ingredients like Qing Dai tends to have a draining effect in the body because they clear accumulations, remove Phlegm and soften hard lumps.
The tastes of ingredients in TCM also determine what Organs and Meridians they target. As such Qing Dai is thought to target the Stomach, the Liver and the Lung. In TCM the Stomach is responsible for receiving and ripening ingested food and fluids. It is also tasked with descending the digested elements downwards to the Small Intestine. The Liver on the other hand is often referred as the body's "general" because it is in charge of regulating the movements of Qi and the Body Fluids. It also takes a leading role in balancing our emotions. In addition to performing respiration, the Lungs are thought in TCM to be a key part of the production chain for Qi and the Body Fluids that nourish the body.