Can Polygonatum (Huang Jing) and Rehmannia glutinosa (Shu Di Huang) be used together?
Generally speaking, Polygonatum (Huang Jing) and Rehmannia glutinosa (Shu Di Huang) can be used together, but it is important to follow medical advice when using them. The detailed explanation is as follows:

Polygonatum has effects of nourishing Qi and yin, strengthening the spleen, moistening the lungs, and benefiting the kidneys, and is suitable for treating symptoms such as liver yin deficiency, heart and lung dryness, and spleen and stomach weakness. Rehmannia glutinosa can nourish the blood and yin, and enrich essence and marrow, and is suitable for treating conditions such as blood deficiency and kidney yin insufficiency.
Drinking water infused with both Polygonatum and Rehmannia glutinosa together will not cause any conflicting reactions between the components of the two herbs, nor will it produce harmful substances; therefore, they can be used simultaneously. However, patients must strictly follow medical instructions when taking the herbs, avoiding excessive dosage, which may cause discomfort symptoms such as abdominal distension and diarrhea.
In addition, people allergic to the above two herbs should not use them, as they might experience adverse reactions such as skin itching and rashes. Pregnant and lactating women should use them only under the guidance of a physician to avoid affecting fetal development or causing discomfort in infants.