A persistent dry cough with minimal or no phlegm; the throat feels dry, raw, and uncomfortable; the cough is worse at night or after talking; occasionally a small amount of sticky white mucus is produced that is difficult to expectorate; there is no fever, no sore throat in the infectious sense, no colour in the sputum. Western medicine investigates and finds no structural pathology — no asthma, no infection, no reflux-induced bronchospasm. In TCM, this cluster represents the classical pattern of Lung-Stomach Yin deficiency with counterflow Qi (fei wei yin xu qi ni): the Lung’s mucosal fluids are depleted, producing dryness and irritation; the depleted Yin fails to anchor Qi descending, allowing it to surge upward as cough; the same Yin deficiency affects the Stomach, producing dry mouth, hunger without appetite, and nausea. Zhang Zhongjing’s formula for this pattern is Mai Men Dong Tang (Ophiopogon Decoction), recorded in the Jin Kui Yao Lue with characteristic brevity: "Major counterflow and surging Qi, throat not smooth — Mai Men Dong Tang governs."

I. Classical Source and Formula Status

Mai Men Dong Tang is recorded in Jin Kui Yao Lue · Lung Wilting, Lung Abscess, Cough and Upper-Qi Disease: "Fire counterflowing and surging upward, throat not smooth, to stop the counterflow and descend Qi: Mai Men Dong Tang governs." The “fire” here is deficiency-fire from Yin depletion, not excess-Heat. The formula is included in the National Administration of Traditional Chinese Medicine’s Ancient Classical Formulas Catalogue, confirming its historical documentation and clinical safety profile across two thousand years.

The formula’s compositional insight: rather than directly treating the cough with antitussive herbs, it rebuilds the Yin fluid substrate that allows Qi to descend naturally. When Lung and Stomach Yin are restored, the counterflow Qi resolves without being directly suppressed. This upstream treatment approach is the formula’s defining character and the reason it remains effective where antitussive symptomatic treatment has repeatedly failed.

II. Six-Herb Composition, the 7:1 Ratio, and Formula Analysis

Classical composition: Mai Men Dong 7 sheng · Ban Xia 1 sheng · Ren Shen 3 liang · Gan Cao 2 liang · Jing Mi 3 he · Da Zao 12 pieces. Modern clinical reference doses: Mai Dong 40–60g · Ban Xia 6–10g · Ren Shen 6–10g (or Dang Shen 15–20g) · Zhi Gan Cao 6g · Jing Mi 15g · Da Zao 4 pieces. Mild or wellness-adjustment doses may be proportionally reduced.

The 7:1 Mai Dong to Ban Xia ratio — the formula’s defining compositional innovation: Mai Dong is used at a dramatically dominant dose (7 sheng vs Ban Xia’s 1 sheng — approximately 7:1). This ratio is deliberate and architecturally significant:

• Pure Yin-supplementing formulas without any descending action risk becoming cloying and obstructing Spleen-Stomach transportation, preventing the nourishing action from reaching its targets
• Ban Xia is pungent-warm and would normally aggravate Yin deficiency if used in standard doses; at a 1:7 ratio, it is just sufficient to move the Qi mechanism and prevent cloying — while completely subordinated to Mai Dong’s moistening action
• The result: moist without cloying, descending without drying — the formula simultaneously nourishes Yin and descends Qi without either action compromising the other

This 7:1 ratio is the most frequently cited example of TCM’s “opposite nature, synergistic action” (xiang fan xiang cheng) compositional principle.

Chief herb — Mai Men Dong (Ophiopogon) 40–60g: sweet-slightly cold; enters Lung, Stomach, Heart. Nourishes Lung-Stomach Yin, generates fluids and relieves thirst, moistens the Lung and clears Heart. Heavy dosing is essential: Mai Dong’s moistening action on the Lung mucosa (“converting dry Lung to moist Lung”) requires sufficient quantity to rebuild substantially depleted fluid reserves. In moderate doses it supplements; at high doses it can actually reverse the Yin depletion driving the pattern. Its dual Lung-Stomach action makes it uniquely appropriate for this combined Lung-Stomach Yin-deficiency pattern.

Deputy herb — Ban Xia 6–10g: pungent, warm; enters Spleen, Stomach, Lung. Descends counterflow and harmonises Stomach, dissolves Phlegm and disperses stuffiness. At this low dose in a Mai Dong-dominant formula, Ban Xia’s role is precisely defined: (1) descends the Qi counterflow driving the cough; (2) prevents Mai Dong’s high-dose moistening from becoming cloying and obstructing Spleen-Stomach transportation; (3) dissolves the small amount of sticky viscous Phlegm generated by the Yin deficiency. Use processed Ban Xia (Fa Ban Xia or Jiang Ban Xia); raw Ban Xia is toxic.

Assistant herbs — Ren Shen, Da Zao, and Jing Mi:

• Ren Shen 6–10g (or Dang Shen 15–20g): supplements Spleen-Stomach Qi and generates fluids. The Spleen-Stomach is the source of fluid generation (“postnatal root” — 后天之本); strengthening Spleen-Stomach function enables the body to generate its own Yin fluids on an ongoing basis, making Mai Dong’s action self-sustaining rather than a temporary supplement. Pei tu sheng jin (“cultivating Earth to generate Metal”) — strengthening Spleen generates Lung-sustaining Qi and fluids.
• Da Zao 4 pieces: sweet, warm; supplements Middle Jiao Qi and nourishes Blood; assists Ren Shen in Spleen-Stomach strengthening; moderates the formula’s slight cold tendency.
• Jing Mi (round-grain white rice) 15g: sweet, neutral; supplements Middle Jiao Qi, nourishes Stomach Yin, and moistens. Jing Mi’s role is direct Stomach-Yin nourishment and palatability improvement; it is cooked with the herbs and not strained out, making the decoction a gentle Stomach-nourishing liquid. Modern practice often omits Jing Mi for convenience without significant loss of efficacy when Ren Shen and Da Zao doses are maintained.

Envoy — Zhi Gan Cao 6g: supplements Qi, harmonises all herbs; moderates Mai Dong’s slight cold with warmth; moderates Ban Xia’s pungent-warm with sweetness; relieves pharyngeal dryness directly.

Formula architecture: nourish Lung-Stomach Yin (Mai Dong, Da Zao, Jing Mi, Zhi Gan Cao) — the upper and middle treatment; supplement Spleen Qi to generate fluids from within (Ren Shen, Da Zao, Jing Mi, Zhi Gan Cao) — the root treatment; descend counterflow Qi and prevent cloying (Ban Xia) — the facilitating treatment. The formula treats from above (Lung), below (Stomach), and from the source (Spleen).

III. Two Core Indications and Pattern Identification

1. Deficiency-Heat Lung Wilting (xu re fei wei) — primary classical indication
Chronic dry cough; minimal or absent expectoration; when expectoration occurs: small amounts of white sticky mucus or thin frothy sputum, difficult to clear; low cough sound (distinguishing from productive Wind-Cold or Heat-Wind cough); throat dry, rough, and sore; voice hoarseness; breathlessness; hot palms and soles; dry mouth worsened at night; red tongue, scant coating or no coating; thin-rapid pulse. Triggered or worsened by: prolonged illness consuming Lung Yin, seasonal dryness, chronic overwork and late nights, or post-COVID Lung-Yin depletion.

2. Stomach Yin deficiency (wei yin bu zu) — second major indication
Stomach dryness and dull aching; hunger without appetite or with inability to eat much; dry mouth and thirst; nausea and dry retching; belching; post-meal upper abdominal discomfort; constipation (intestinal dryness); emaciation. Stomach and Lung share fluid metabolism: Lung receives descending Stomach-generated fluids; when Stomach Yin is depleted, Lung loses its fluid source, and dry cough may develop secondarily. This reflects TCM’s “Lung-Stomach common origin” (肺胃同源) principle.

Key discriminators: Mai Men Dong Tang is not appropriate for: Wind-Cold cough (thin clear sputum, chills, floating-tight pulse); Wind-Heat cough (yellow sputum, fever, sore throat with redness, rapid pulse); Phlegm-Damp cough (copious white sputum, white greasy coating). All three represent exterior or excess patterns requiring different approaches. The formula is strictly for the deficiency-dryness pattern: insufficient Yin fluids, counterflow Qi from Yin failing to anchor, no active exterior pathogen, no excess phlegm.

IV. Modern Clinical Applications and Modifications

Respiratory applications (Lung Yin deficiency): chronic bronchitis (dry cough phase); chronic pharyngitis; vocal cord nodules and hoarseness; post-COVID residual dry cough and throat dryness; Sjögren’s syndrome airway manifestations; bronchiectasis in stable phase with dry cough. Modifications: sore throat and pharyngeal dryness → add Xuan Shen 10g, Sheng Di 12g; dry cough severe → add Sha Shen 12g, Yu Zhu 10g, Tian Hua Fen 12g; voice hoarseness → add Pang Da Hai 9g, Hu Zhang 12g.

Gastric applications (Stomach Yin deficiency): atrophic gastritis; gastro-oesophageal reflux disease (Stomach Yin type: burning without excess acid, dryness, hunger without appetite); functional dyspepsia; post-chemotherapy nausea and gastric Yin depletion. Modifications: nausea-vomiting severe → increase Ban Xia to 10g, add Zhu Ru 9g, Pi Pa Ye 9g (wrapped); dry retching → add Shi Hu 12g, Yu Zhu 10g; constipation → add Huo Ma Ren 15g, Yu Li Ren 12g.

Common modifications:

• Yin deficiency with prominent Heat (dry mouth, hot palms, night sweats): add Xuan Shen 10g, Sheng Di 12g, Zhi Mu 10g
• Qi deficiency co-pattern (fatigue, breathlessness): increase Ren Shen; add Huang Qi 15g; use Hong Shen
• Dry cough without sputum: add Bei Sha Shen 12g, Yu Zhu 10g, Tian Hua Fen 12g
• Haemoptysis (Lung Yin deficiency with Blood-Heat): add Han Lian Cao 10g, Bai Mao Gen 15g, Ce Bai Ye 12g
• Sore throat and hoarseness: add Pang Da Hai 9g, Mu Die Zi 6g
• Constipation from intestinal dryness: add Huo Ma Ren 15g, Yu Li Ren 12g, Feng Mi 30g (dissolve into strained liquid)

V. Usage, Dosage, and Safety

Preparation: soak all herbs 30 minutes; add Jing Mi (do not strain out — cook until soft); boil then simmer 30–40 minutes; take 2 warm doses daily (morning and evening). The formula should be taken warm — cold liquid would counteract its Stomach-warming action. Patent forms: Hai Tian Fu Fang Mai Dong granules (Mai Men Dong Tang) and Nong Ben Fang Mai Men Dong Tang.

Course: chronic conditions (chronic pharyngitis, atrophic gastritis, chronic dry cough) typically require 2–4 weeks minimum; do not expect immediate results — Yin restoration is gradual. Acute Lung-Yin depletion (post-COVID residual dry cough) may respond within 1–2 weeks.

Contraindications: Spleen-Stomach Cold deficiency with loose stool and cold aversion (Mai Dong’s slightly cold, moistening quality will worsen Cold-Damp; if needed, reduce Mai Dong dose significantly and add warming herbs); Phlegm-Damp cough (white greasy coating, copious phlegm — formula’s moistening action will worsen); Wind-Cold or Wind-Heat cough (exterior pattern — requires exterior resolution first); allergy to any component; pregnant women (Dang Shen/Ren Shen and Ban Xia require supervision).

Dietary support: snow pear, silver ear (Tremella), lily bulb, lotus root, yam, honey water — all moistening Lung-Stomach foods that amplify the formula’s effects. Avoid: spicy, dry-fried, roasted, and pungent foods (chilli, garlic, deep-fried) that worsen dryness; smoking and passive smoke exposure; strong hot tea and coffee; alcohol (all further deplete mucosal fluids).