In Traditional Chinese Medicine (TCM), Du Huo 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 Du Huo is Warm in nature. This means that Du Huo 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 Du Huo can help restore a harmonious balance between Yin and Yang.
Du Huo also tastes Bitter and Pungent. 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 Du Huo 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.
The tastes of ingredients in TCM also determine what Organs and Meridians they target. As such Du Huo is thought to target the Bladder and the Kidney. In TCM the impure water collected by the Kidneys that cannot be used by the body is sent to the Bladder for storage and excretion as urine. 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.