In Traditional Chinese Medicine (TCM), Ju Hua belongs to the 'Cool/Acrid herbs that release the Exterior' category. Herbs that release the Exterior aim to to treat the early stages of diseases that affect the upper respiratory tract, the eyes, the ears, the nose, the throat or the skin. TCM believes that External diseases such as colds or allergies can only invade the body if the External environment overwhelms our Wei Qi (the TCM version of the immune system). In order to counteract this invasion Cool/Acrid herbs aim to induce sweating by dilating our capillary pores so that they release more sweat. The belief is that this will expel the disease from the body and stop it from invading further.
As suggested by its category Ju Hua is Cool in nature. This means that Ju Hua tends to help people who have too much 'Heat' in their body, although with less effect than a plant that would be Cold in nature. 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 Ju Hua can help restore a harmonious balance between Yin and Yang.
Ju Hua 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 Ju Hua 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 Ju Hua is thought to target the Liver and the Lung. In TCM the Liver 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.