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[Poisonous Herb] Strongly purges internal accumulation of water and dampness
The leaves of Genkwa Flos (Yuanhua) are pointed like willow leaves. The flowers are purple, resembling those of Vitex negundo (Jing).
Stem of Wikstroemia indica (Raohua)
The stem has no thorns. The flowers are fine and yellow in color. Regarding their properties, Yuanhua is acrid, bitter, and warm; whereas Raohua is acrid, bitter, and cold. In terms of therapeutic indications, due to its acrid-warm nature, Yuanhua has the power to reach the exterior and move water. Raohua, being cold in qi, has the effect of entering the interior and draining downward. Therefore, medical texts record that it can treat dysentery. (Lei Xiao stated: Zhang Zhongjing used Raohua to treat dysentery in *Shanghan Lun* (Treatise on Cold Damage), taking advantage of its ability to promote urination. Once the water is removed, the dysentery stops. This was his intent. When using it now, one must exercise caution and not overuse it, lest adverse effects occur. It should only be used when specific symptoms are present.) However, they all belong to substances that break up accumulations and drive out fluid retention, and should not be viewed separately. It is merely that pharmacies often mix them up, yet efficacy can still be seen, because their main therapeutic functions are similar.

[Poisonous Herb] Strongly purges water and dampness from the meridians and collaterals
Kansui Radix (Gansui) (Specifically enters the Spleen, Stomach, Lung, Kidney, and Bladder channels). The skin is red, the flesh is white, the taste is bitter, the qi is cold, and it is toxic. Its nature is purely yin. Therefore, medical texts all record that it can act upon the Kidney channel and places where water qi condenses in the tunnels or collaterals, surging forth and breaking through directly, causing all water-dampness to exit through the anus. It is the primary herb for descending water-dampness. (Li Gao stated: When water pathogen knots in the chest, this herb cannot be omitted. Hence, Zhang Zhongjing uses it in Da Xianxiong Tang (Major Intractable Chest Decoction). But it is toxic and should not be used lightly.) Yu Jiayan said: The Stomach is the sea of water and grain, the source of the five zang and six fu organs. If the Spleen fails to scatter the water essence from the Stomach to the Lung, disease arises in the middle; if the Lung fails to regulate the water pathway from the Stomach to the Bladder, disease arises in the upper; if the Kidney fails to manage the gate of the Stomach and control its storage and discharge, disease arises in the lower. This leads to accumulating water overflowing without limit. (Edema is divided into five types: Fengshui (Wind Edema), Pishui (Skin Edema), Zhengshui (True Water Edema), Shishui (Stone Water Edema), and Huanghan (Yellow Sweat). When water stagnates in the Heart, there is heart vexation, shortness of breath, and inability to lie comfortably. When water stagnates in the Lung, there is distension, wheezing, and coughing. When water stagnates in the Liver, there is fullness and pain under the ribs radiating to the lower abdomen. When water stagnates in the Spleen, there is heaviness and discomfort in the four limbs, making it difficult to wear clothes. When water stagnates in the Kidney, there is abdominal pain radiating to the back, and pain in the waist and thighs. Edema differs from Qi edema. Edema has a bright luster, thin and smooth skin, develops slowly, usually rising from below, feels like mud when pressed, and has clear boundaries. Qi edema has a sallow-yellow complexion, thick skin, rises suddenly, has no clear boundaries, distension may extend to the chest and hypochondrium, pain may involve the zang-fu, or appear suddenly like swelling, or rise from top to bottom, or cover the whole body, rebounding immediately after pressing. However, the edema discussed by Zhang Zhongjing is mostly caused by external pathogens with internal injury as a secondary factor. Ultimately, water is extreme yin, and its root lies in the Kidney. If Kidney qi is deficient, water lacks mastery and acts recklessly. If one does not warm the Kidney and tonify the Spleen, but merely uses herbs to move qi and promote urination, this is ultimately not the principle of guiding water back to the Kidney. It is like soil turning to mud in rain; only with gentle wind and warm sun can dampness transform into harmonious yang, allowing the natural cycle of growth and decline of all things to resume!) Therefore, whenever real pathogenic factors cause obstruction in the meridians due to cold, presenting as edema, gu-zhang (abdominal distension with visible veins), hernia, masses, and abdominal pain, in patients whose primal qi is robust (only those who are robust can use Kansui), one relies on this swift and potent herb as the first choice to open and drain the water pathways, such as in Zhang Zhongjing's Da Xianxiong Tang. However, if the condition is not excess but rather deficiency of Middle Qi, leading to urinary retention, reckless flow of fluids, and the Spleen's inability to control them, mistakenly using draining substances will further deplete the deficiency. Although water may temporarily leave, life will surely follow. Gancao (Licorice Root) texts state it is contrary to this herb. Why are they used together yet have biased effects? It is also because Gansui's action of moving downward is extremely urgent. (Additionally, Liu Hejian noted: For edema that has not fully resolved after medication, apply Kansui powder around the navel on the abdomen, and internally administer Gancao water. The edema then subsides. Though these two herbs are contrary, their interaction is thus.) Those not deeply versed in this way find it hard to discuss this. The best quality has red skin, white flesh, and roots that are bead-like and heavy. Wrap in flour and roast until cooked. (Soak in Gancao and Qiji juice for three days until the water turns black, then clear. Then wrap in flour and roast.) Digiti Melonis Fructus Seed (Gua Di) serves as the guide drug. Avoids Polygala tenuifolia (Yuan Zhi).