In Traditional Chinese Medicine (TCM), Qian Nian Jian 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 Qian Nian Jian is Warm in nature. This means that Qian Nian Jian 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 Qian Nian Jian can help restore a harmonious balance between Yin and Yang.
Qian Nian Jian also tastes Bitter, Pungent 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 Qian Nian Jian 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 Pungent ingredients tend to promote the circulations of Qi and Body Fluids. That's why for instance someone tends to sweat a lot when they eat spicy/pungent food. Lastly 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 Qian Nian Jian is thought to target the Kidney and the Liver. According to TCM, the Kidneys do not only regulate the urinary system but also play a key role in the reproductive system and the growth and aging process of the body. 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.