According to legend, when the Song dynasty medical officer Li Defense first joined the palace as a medical officer, a favorite concubine of Emperor Huizong was suffering from a coughing disorder, her face was swollen like a plate and she was in pain and stayed up all night. Seeing the seriousness of the disease, Emperor Huizong urgently recruited the doctor Li Defense to treat it. The emperor was so upset that he made him sign a pledge that he would be executed if he did not get results in three days. Li was at home worrying about the lack of a good solution when he heard someone outside the door selling cough medicine: “Cough medicine for one post, eat it and sleep tonight.” Lee immediately sent someone to buy ten posts, only to see the medicine light green, only need to use light vegetable soup with a few drops of sesame oil to transfer to serve. Li fear of strong medicine, it will be three posts of medicine together with their own trial, after serving no discomfort, so another three posts combined into one, brought into the official to the Imperial Consort, told her to take in two. The imperial concubine stopped coughing that night after taking it, and the swelling of her face disappeared the next morning. The emperor was so pleased that he gave her ten thousand pieces of gold. Li was afraid that the emperor would ask for the prescription, but how could he explain that he did not know it? He asked his servant to invite the medicine seller to his home, and offered to buy the prescription with a large sum of money. The medicine seller told the truth, in fact, the drug is very simple, only a taste of sea clam shells, put on the new tile calcined to red, crushed into the end, mixed with a little green diaphanous that is. The medicine seller to get this recipe began when the youth from the army, the party was later called Dai clam or green clam. Sea clam shells are bitter, salty, cold in nature, belonging to the lung, kidney and stomach meridians, with functions of clearing heat and resolving phlegm, softening hardness and dispersing knots, controlling acidity and relieving pain. It is used for cough with phlegm and fire, pain in chest and ribs, blood in phlegm, stomach pain and acid swallowing, etc.; externally for eczema and burns. Qing Dai is a dried powder, mass or granule made from the processed leaves or stems and leaves of Malan, Polygonum and Woad, salty in taste, cold in nature, belongs to the liver meridian, functions to clear heat and detoxify, cool the blood, and set the alarm. It is used for warm poisonous spot, blood fever and epistaxis, chest pain and coughing blood, mouth sores, mumps, throat paralysis, pediatric epilepsy. Dai Clam San, which is based on sea clam shell, is a common medicine for clearing lung and relieving cough. Composition: 30 grams of Qing Dai, 300 grams of sea clam shells. Character: Dispersion. This product is gray-blue powder; taste light. Functions and Indications: Clearing the liver and lung, lowering rebelliousness and relieving cough. It is used for liver and lung heat, dizziness and tinnitus, cough and asthma, lung impotence and lung carbuncle, pharyngeal discomfort, thirst and irritability. Usage and dosage: Take orally, 1 time 6 grams, 1 time daily. Please never doubt the real efficacy of this Di Clam San, which is really effective in treating cough. The cough is caused by a very heavy and frequent cough, and the coughing bouts are mostly caused by liver fire taking advantage of the lungs. In the case of tracheal wall swelling, the cough is usually more severe and must be relieved by coughing out phlegm, but immediately coughing again, which is generally not effective with Chinese medicine. At present, Western medicine treatment is cryosurgery of tracheal wall tumors, and the cough is relieved when the tumor disappears. This kind of cough is generally identified by Chinese medicine as liver fire offending the lungs, and the use of Di Clam San to relieve the cough will have a miraculous effect. The clinical treatment of Di Clam San is not only for coughs of tracheal wall tumors, but also for heavier and more frequent coughs, with satisfactory results. It is true that “the first thing to do with a prescription is to understand the reason, and if the reason is not clear, the good prescription is useless”.