【Nature and flavor and meridians】Sweet, salty, cold.
 【Function】Cools blood, promotes blood circulation, detoxifies and clears rashes.
 [Indications] Blood heat toxicity, purple-black macules, measles that do not break out, sores, eczema, burns caused by water or fire. Warm-heat macules, damp-heat jaundice, purpura, vomiting, epistaxis, hematuria, stranguria, heat-induced constipation, burns, eczema, erysipelas, carbuncle.
 [Precautions] People with weak gastrointestinal tract and loose stools should take the medicine with caution.
 【Medical records】
 "Ben Jing": "It cures evil spirits in the heart and abdomen, treats five kinds of jaundice, replenishes the middle and strengthens the qi, benefits the nine orifices, and clears the water channels."
 "Bie Lu" says: "It can treat abdominal swelling, fullness and pain. It can be used as an ointment to treat sores in children and facial ulcers."
 "Medicine Properties": "It can cure malignant sores and tinea."
 "Compendium of Materia Medica" states: "For treating typhoid fever, if the rashes do not come out, use this medicine to make them come out."
 "Compendium of Materia Medica": "It can treat rashes and pox, promote blood circulation and cool blood, and benefit the large intestine."
 "Medical Collection": "Nourishes the heart, soothes the liver, disperses blood stasis, and activates blood circulation."
 【Predecessors release medicine】
 "Compendium of Materia Medica": "Purple grass is good at cooling blood and activating blood circulation, and benefiting the large and small intestines. Therefore, it is suitable for those who are about to break out of pox, have excessive blood heat and toxicity, and have constipation. It can also be used for those who have broken out but have purple and black constipation. If the pox has broken out and the red and active, or the white and sunken pox, it should be avoided. Therefore, Yang Shiying's "Direct Pointing Prescription" says that purple grass can treat pox and can lead to defecation, making it lighter. It is especially beneficial to add costus root and white atractylodes. Zeng Shirong's "Huo You Xin Shu" also says that purple grass is cold in nature, and can be used for children with strong spleen qi, but it can be used as a laxative for children with weak spleen qi. The ancient prescription only used velvet, taking its initial yang energy, and like to like, so it was used to treat pox. People today do not understand this principle and use it indiscriminately, which is wrong."
 "Compendium of Materia Medica" states: "Purple grass is an essential medicine for cooling blood, so it is used to treat evil heat in the heart and abdomen. The five types of jaundice are caused by damp heat in the spleen and stomach. If it can remove dampness, heat and orifices, the jaundice will heal itself. Evil heat in the body can damage the middle qi, and dissipating the evil heat can replenish the middle qi. It is bitter, cold and slippery, so it can benefit the nine orifices and clear the water channels. If the abdomen is swollen, full and painful, the damp heat will be resolved and discharged through urination, and the previous symptoms will be eliminated. Combined with plasters to treat children's pox and facial acne, all of which have the effect of cooling blood."
 "Compendium of Materia Medica" states: "Purple grass is suitable for those with pox that is in the process of coming out but not coming out yet, and is red and dry, and those that have come out but have constipation and are purple and black. It is also suitable for pox with black boils. If the pox is already uniform and red, and the bowel movements are smooth, use purple grass instead... It is used to activate blood circulation and promote the growth of the blood when the blood heat is not cleared. If the red is active, the bowel movements are slippery, and the white is sunken, avoid it. If the bowel movements are gray and stagnant but the bowel movements are slippery, use purple grass from the insect section, and you should take a look at it."
 "Compendium of Materia Medica Chongyuan Collection" says: "The current method often uses lithospermum officinale as a cooling agent to relieve smallpox poison, which is mostly caused by cold syndrome. However, Shizong first used Guizhi Decoction to transform the qi of the sun, and when the qi is transformed, the poison will not remain. There is also a method of adding honeysuckle and lithospermum officinale to Guizhi Decoction."
 "Compendium of Materia Medica" states: "Purple grass has a bitter and cold smell and a purple color that enters the blood, so it clears the heat in the blood. In ancient times, it was used to treat heat accumulation in the internal organs. Later generations specialized in treating smallpox and ulcers, and also treated rashes, all of which were aimed at cooling blood and clearing heat. Yang Renzhai used it to treat constipation caused by carbuncle, so it can be used for all external ulcers with heat in the blood. Moreover, it can be used for all diseases with heat in the blood, as well as bloody diarrhea, hemorrhoids, hematuria, and stranguria caused by strong qi and evil. But nowadays, people only think of it as a special medicine for smallpox, and those who treat blood heat diseases and external ulcers are all unaware of it, which is a mistake."