【Nature and flavor and meridians】Sweet, neutral.
 【Function】Strengthen the spleen, nourish the lungs, consolidate the kidneys, and improve the essence.
 [Indications] Spleen deficiency diarrhea, chronic dysentery, consumptive cough, thirst, spermatorrhea, leucorrhea, frequent urination. Tonifies the spleen and stomach, promotes fluid production and benefits the lungs, and nourishes the kidneys and astringes semen. Used for spleen deficiency, poor appetite, chronic diarrhea, asthma and cough due to lung deficiency, spermatorrhea due to kidney deficiency, leucorrhea, frequent urination, and thirst due to deficiency heat. Fried yam with bran tonifies the spleen and stomach. Used for spleen deficiency, poor appetite, diarrhea, loose stools, and excessive leucorrhea.
 【Precautions】Do not take this medicine if you have solid evil.
 ① "Compendium of Materia Medica" says: Ganoderma lucidum is the messenger, and it hates sweetness. ② "Tangye Materia Medica" says: Ermendong is the messenger.
 【Medical records】
 "Ben Jing": "It is used to treat injuries, replenish deficiency, eliminate cold and heat evil spirits, replenish the middle and strengthen the body, grow muscles, and long-term use can improve hearing and eyesight."
 "Bie Lu": "It can treat wind wandering in the head and face, wind head (also known as 'head wind') and dizziness, relieve gas, stop waist pain, treat asthenia and emaciation, replenish the five internal organs, eliminate restlessness and heat, and strengthen the joints."
 "Materia Medica": "It can replenish the five kinds of fatigue and seven kinds of injuries, remove cold wind, stop waist pain, calm the mind, replenish the insufficient heart qi, and can be used for patients with physical weakness."
 "Dietary Therapy Materia Medica": "It can cure headaches and help boost yin energy."
 "Rihuazi Materia Medica": "It helps the five internal organs, strengthens the tendons and bones, improves the mind and calms the spirit, and cures spermatorrhea and forgetfulness."
 Zhu Zhenheng: "Pounding and applying the raw material to the swelling and hard toxins can dissipate it."
 "Shang Han Yun Yao": "Replenish the deficiency and clear the deficiency heat."
 "Compendium of Materia Medica": "It nourishes the kidney qi, strengthens the spleen and stomach, stops diarrhea, resolves phlegm and saliva, and moisturizes the skin and fur."
 【Predecessors release medicine】
 Li Gao: Zhongjing Bawei Wan uses dried yam because it is cool and nourishing. It can also treat dry skin by moistening it.
 "Yi Jing Su Hui Ji" says: Although dried yam enters the hand Taiyin meridian alone, it can also strengthen the yin. Moreover, the hand Taiyin is the upper source of the foot Shaoyin. Since the source is nourishing, the flow will surely be beneficial.
 "Compendium of Materia Medica": Chinese yam can strengthen the spleen and replenish deficiency, nourish essence and strengthen the kidney, treat all kinds of deficiency and damage, and cure five kinds of fatigue and seven kinds of injuries. However, its qi is light and slow, so it is not suitable for special tasks. Therefore, to replenish the spleen and lung, ginseng and astragalus must be used, and to replenish kidney water, cornel and rehmannia must be used. It is astringent and turbid, so it must be broken and ground together. Cuscuta australis can help to cure incontinence. All pills are made of pills, and they should also be ground into paste. In short, the nature and taste are weak, but it can be used as an adjuvant.
 "Pharmaceutical Chemistry": Chinese yam is warm and nourishing without being abrupt, slightly fragrant without being dry, and has the function of regulating the lungs. It is a good medicine for treating chronic cough caused by lung deficiency. Because it tastes sweet and has a fragrant smell, it can help the spleen and treat diarrhea caused by spleen deficiency, laziness and sleepiness, and fatigue of the limbs. In addition, its sweetness can nourish yang, and it can nourish the middle and replenish qi, warm and nourish the muscles. It is an important medicine for the lungs and spleen. The earth is strong and produces gold, and the gold is strong and produces water. The functions are the same, so it is used in Liuwei Pills to treat kidney deficiency and low back pain, spermatorrhea, nocturnal emission, and impotence caused by weakness. However, it is slow in nature and weak in effect, so the dosage should be doubled.
 "Compendium of Materia Medica" states: Chinese yam is originally a food. Ancient people used it in decoctions, saying that it can nourish the spleen, replenish qi and remove heat. However, although the qi is warm, it is flat. It nourishes the yin of the spleen and lungs, so it can moisturize the skin and hair and grow muscles. It is not like Astragalus, which is warm in nature and can nourish the lung yang, and Atractylodes, which is bitter and dry and can nourish the spleen yang. Moreover, it is astringent in nature and can cure spermatorrhea. It tastes sweet and salty, and can nourish the kidney and strengthen yin. Therefore, Liuwei Dihuang Pills use it to assist Rehmannia. However, although it is yin in nature, it is not very stagnant, so it can penetrate dampness to stop diarrhea. Raw pounding and applying to carbuncle can reduce swelling and hardness, which also means nourishing yin and reducing fever. As for the saying that it can nourish yang and reduce swelling, replenish qi and remove stagnation, although the logic is understandable, the language is involved and confusing, and it seems not to be correct. As for using it in decoctions to treat fire deficiency and critical symptoms, it is difficult to achieve immediate results. It must be used more often to cure it because of its gentle nature. It should be used raw in nourishing yin medicines, and fried until yellow when used to nourish the spleen.
 "Reading the Classic of Materia Medica": Chinese yam can nourish the kidney and replenish essence. If the essence is sufficient, the yin will be strong, the eyes will be bright, and the ears will be sharp. All the top-grade medicines are ordinary food, not medicines for treating diseases. Therefore, Shennong also proposed the words "long-term use". It can be seen that people nowadays often take top-grade medicines, such as ginseng, cooked earth, lily, donkey-hide gelatin, dodder seed, and astragalus, to treat serious diseases, which has caused countless mistakes. Because the disease is not cured quickly, the vitality will be damaged day by day, and the damage will be extreme and death will occur. All top-grade medicines should be taken for a long time, for a lifetime or for a few years, and they should be supplemented with the five grains to achieve longevity. If you need this medicine for a serious illness, as the five grains are the first to nourish the spleen, people with spleen deficiency can be forced to eat grains to complete the work of nourishing the spleen. Is this reasonable? 7. "Ben Jing Shu Zheng": Chinese yam is mainly used to replenish the deficiency and weakness in the middle, that is, to replenish the middle and increase the strength. Why does Ben Jing mention this again? This should be read in conjunction with the following sentence, which says that it treats injury to the middle, replenishes the weak and thin, and removes the evil qi of cold and heat. It is like saying that it replenishes the weak and thin caused by injury to the middle, and removes the evil qi of cold and heat caused by injury to the middle. For weakness must be caused by one place first, and the other places are related to it. Although it is said that the qi must be weak where the evil gathers, there is also a distinction between yin and yang, and the differences between the five zang organs and six bowels; the evil of weakness treated by Dioscorea must be determined to be caused by injury to the middle and qi, so that it can be correct. Otherwise, injury to the blood and other injuries can also cause weakness and thinness, and cause cold and heat, so what is the difference? The main purpose of Bie Lu is to replenish the weak and thin, replenish the five zang organs, and remove irritability and heat, which is consistent with Ben Jing, but the three items of lowering qi, stopping waist pain, and strengthening yin are special. As for wandering wind in the head and face, headache, and dizziness, doctors have not used this ingredient much since the Tang Dynasty, so there is no way to understand its essence. However, considering that Zhang Zhongjing treated hundreds of diseases caused by wind, and Ben Jing eliminated cold and heat evil spirits, we can also understand its purpose.