"Erdong Tang" (Two-Winter Decoction): A Representative TCM Formula for Dry Throat and Mouth

Erdong Tang originates from Medical Mind Awakening (Yi Xue Xin Wu) by the Qing dynasty physician Cheng Guopeng (Zhongling). Because the formula uses two herbs — Maidong (Ophiopogonis Radix) and Tiandong (Asparagi Radix) — it is named Erdong Tang, the "Two-Winter Decoction."

The composition of the formula (dosages converted to modern measures) is: Tiandong 6g, Maidong 9g, Tianhuafen (Trichosanthes Radix) 3g, Huangqin (Scutellariae Radix) 3g, Zhimu (Anemarrhenae Rhizoma) 3g, Hey e (Nelumbinis Folium) 3g, Renshen (Ginseng Radix) 2g, Sheng Gancao (raw Glycyrrhizae Radix) 2g. Decode with water: add 1000 ml water, decoct to 300-400 ml, divide into two equal portions, take twice daily, once after breakfast and once after dinner.

Erdong Tang has the actions of nourishing yin and clearing lung heat, and generating fluids to stop thirst. It is used for dual damage to qi and yin and lung yin deficiency, presenting with thirst and excessive drinking, dry throat and mouth, insomnia and frequent dreaming, poor appetite, fatigue and weakness, a red tongue, and a rapid fine pulse. The clinical basis for using this formula is mainly thirst with excessive drinking, dry throat and mouth, and a red tongue. Its formula verse goes: "Yin-nourishing and heat-clearing Erdong Tang, use this formula for thirst and excessive drinking; Tiandong, Maidong, Huangqin, Tianhuafen, Hey e, Gancao, Zhimu, Renshen." From the verse it can be seen that this is a formula primarily for treating thirst and excessive drinking.

This formula can be used for hyperthyroidism, diabetes, Sjogren's syndrome, dry cough, and other conditions presenting with the above symptoms. Modern pharmacological studies have confirmed that this formula has a blood-sugar-lowering effect, but the effect is not significant; therefore, this formula can only be used as an adjunctive treatment for diabetes and cannot alone treat diabetes.

When this formula is used to treat hyperthyroidism and diabetes, it must be taken long-term to be effective. Therefore, if patients are unwilling to decoct herbs daily, they may prepare a larger batch of herbs in the corresponding proportions, grind them into fine powder with an herb mill, and make into pills, each pill weighing 10g. Take three times daily, one pill each time, swallowed with plain water after meals.

If the patient has severe dry mouth, an appropriate amount of Jiaogulan (Gynostemma), Wumei (Mume Fructus), Shihu (Dendrobii Caulis), and Xuanshen (Scrophulariae Radix) may be added to stop thirst and generate fluids. For patients with severe vexation and insomnia, Suanzaoren (Ziziphi Spinosae Semen), Hehuanpi (Albiziae Cortex), and Baiziren (Platycladi Semen) may be added; the formula may also be combined with Gan Mai Dazao Tang (Licorice, Wheat, and Jujube Decoction). If the patient also has constipation, an appropriate amount of Dahuang (Rhei Radix et Rhizoma) and Huomaren (Cannabis Semen) may be added to drain fire and free the bowels.

This formula has a certain effect in treating dry cough and paroxysmal cough. The cause of many dry and paroxysmal coughs is unclear; it may be due to previous respiratory disease or may be caused by other reasons. Western medicine does not have good methods for this type of dry and paroxysmal cough, and this formula may be used. If using this formula alone is not significantly effective, Chuanbeimu (Fritillariae Cirrhosae Bulbus) 3g, Pipaye (Eriobotryae Folium) 6g, Tinglizi (Descurainiae/Lepidii Semen) 3g, and Xingren (Armeniacae Semen) 3g may be added.

For cancer patients who develop dry throat and mouth as a sequela after radiotherapy, this formula may also be used as the main treatment, with additions of Jiaogulan, Wuweizi (Schisandrae Fructus), Shihu, Wumei, and others.