In Traditional Chinese Medicine (TCM), Yi Tang belongs to the 'Tonic herbs for Qi Deficiency' category. Tonic herbs are used for patterns of Deficiency, when one lacks one of the 'Four Treasures' (Qi, Blood, Yin and Yang). Qi tonics are typically sweet and they tend to enter the Spleen and Lungs because these Organs are most involved with the production of Qi.

Furthermore Yi Tang is Warm in nature. This means that Yi Tang 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 Yi Tang can help restore a harmonious balance between Yin and Yang.

Yi Tang also tastes 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. Sweet ingredients like Yi Tang tends 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 Yi Tang is thought to target the Spleen, the Stomach and the Lung. In TCM the Spleen assists with digestion, Blood coagulation and Fluids metabolism in the body. The Stomach on the other hand is responsible for receiving and ripening ingested food and fluids. It is also tasked with descending the digested elements downwards to the Small Intestine. 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.