In Traditional Chinese Medicine (TCM), Cang Er Zi belongs to the 'Herbs that dispel Wind and Dampness' category. These herbs typically help treat what's called 'bi pain' (i.e. painful obstruction) in TCM. This roughly corresponds to arthritic and rheumatic conditions with pain, stiffness and numbness of the bones, joints and muscles.
Furthermore Cang Er Zi is Warm in nature. This means that Cang Er Zi tends to help people who have too much 'Cold' in their body, although with less effect than a plant that would be Hot in nature. Balance between Yin and Yang is a key health concept in TCM. Those who have too much Cold in their body are said to either have a Yin Excess (because Yin is Cold in nature) or a Yang Deficiency (Yang is Hot in Nature). Depending on your condition Cang Er Zi can help restore a harmonious balance between Yin and Yang.
Cang Er Zi also tastes Bitter and Sweet. 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. Bitter ingredients like Cang Er Zi tends to have a cleansing action on the body by clearing Heat, drying Dampness and promoting elimination via urination or bowel movements. On the other hand Sweet ingredients tend to slow down acute reactions and detoxify the body. They also have a tonic effect because they replenish Qi and Blood.
The tastes of ingredients in TCM also determine what Organs and Meridians they target. As such Cang Er Zi is thought to target the Lung. 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.