Wu yu is an alternative name for Cornus officinalis, and the two refer to a kind of traditional Chinese medicine with no difference, which has the effect of dispersing cold and relieving pain, descending the rebelliousness and stopping vomiting (stopping the upward rush of gastric qi, stopping vomiting), and assisting yang in stopping diarrhea. Cornus officinalis is the dried nearly mature fruit of Cornus officinalis, Shihu, or sparse hair Cornus officinalis of the Rutaceae family, hot in nature, pungent and bitter in flavor, with a small poison, and attributed to the liver, spleen, stomach and kidney meridians. It is used in the treatment of syncopal headache (headache caused by the invasion of the syncopal meridian), cold hernia and abdominal pain (acute abdominal pain caused by the coldness of the internal organs and the coldness of the wind), cold-dampness of the feet (cold and dampness invading the feet, causing numbness, soreness and swelling and other discomforts), menstrual cramps, abdominal distension, vomiting and acid swallowing (swallowing of the acid in the stomach that goes up to the mouth and pharynx), and diarrhea at the fifth hour (diarrhea before dawn), and other conditions. Wu Zhu is used as a decoction in water and can also be used externally. Note that this medicine is dry and hot, and should not be used more often or for a longer period of time; it should not be used by people with heat in yin deficiency; pregnant women should be cautious in using it. If there is any discomfort, please go to the hospital in time, and use the right medicine after the physician’s consultation, do not use the medicine by yourself.