Tong Cao (通草) — Rice Paper Plant Pith | TCM Herb Guide

At a Glance

• Herb: Tong Cao
• Chinese name: 通草 (Tōng Cǎo)
• Latin name: Tetrapanacis Medulla
• Nature: Slightly Cold
• Taste: Sweet / Bland
• Meridian: Lung / Stomach
• Category: Herbs that Drain Dampness (Diuretic Herbs)
• Introduction: Tong Cao (通草), Medulla Tetrapanacis, is the dried pith of Tetrapanax papyrifer, the rice paper plant. Lighter and gentler than Mu Tong, it clears heat from the lungs, promotes urination, and unblocks lactation channels. Its very mild, almost tasteless nature and minimal toxicity make it the preferred choice over Mu Tong for promoting lactation and treating mild urinary heat, especially in postpartum women. It is one of the safest diuretic-heat-clearing herbs in the materia medica.

Action

• Clears heat and promotes urination
• Promotes lactation
• Clears damp-heat from the lower jiao
• Clears lung heat and relieves chest oppression

Clinical Application

• Damp-heat dysuria: scanty, dark, burning urine — combines with Hua Shi, Che Qian Zi, Zhu Ye
• Insufficient lactation postpartum — combines with Wang Bu Liu Xing, Mu Tong, Dang Gui, Zhu Ti
• Damp-heat in the middle/lower jiao with urinary difficulty — combines with Yi Yi Ren, Ze Xie
• Lung heat with chest oppression and slight dyspnea — combines with Sang Bai Pi, Huang Qin
• Damp-warm febrile disease (湿温) with dampness in the lower jiao — combines with Huo Xiang, Yi Yi Ren

Precautions

• Dosage: 3–5 g in decoction
• Very gentle — one of the safest heat-clearing diuretics
• Contraindicated in qi deficiency or cold patterns with urinary difficulty
• Use with caution in pregnancy — promotes downward movement
• Distinguish from Mu Tong (木通): Tong Cao is pith (lighter, safer); Mu Tong is stem (stronger action)
• Suitable for postpartum use to promote lactation

Formula

• San Ren Tang (三仁汤) variant: includes Tong Cao to promote urination in damp-warm disease
• Tong Ru Dan (通乳丹): Tong Cao, Wang Bu Liu Xing, Mu Tong, Dang Gui, Zhu Ti — promotes lactation
• Tong Cao Yin (通草饮): Tong Cao, Deng Xin Cao, Zhu Ye, Hua Shi — clears heat, promotes urination for mild heat dysuria

Combinations

• Akebia Pith (通草) + Vaccaria Seed (王不留行) + Pangolin Scales (穿山甲) → promote lactation, unblock breast channels; postpartum insufficient milk
• Akebia Pith (通草) + Plantain Seed (车前子) + Talcum (滑石) → clear heat, promote urination; hot lin and damp-heat dysuria
• Akebia Pith (通草) + Poria (茯苓) + Job’s Tears Seed (薏苡仁) → drain dampness; edema and difficult urination
• Akebia Pith (通草) + Akebia Stem (木通) + Lophatherum Herb (淡竹叶) → clear Heart heat, promote urination; mouth sores and dark urine
• Akebia Pith (通草) + Pig’s Trotters (猪蹄) → Tong Cao Zhu Ti Tang (通草猪蹄汤): promote lactation; postpartum blood deficiency with scanty milk

Pharmacological Effects

• Diuretic
  • mild
• Galactagogue
  • promotes milk secretion
• Anti-inflammatory; antipyretic; mild antibacterial; promotes fluid metabolism in the upper jiao
  • lung pathway

Classic Description

• Ben Cao Gang Mu (《本草纲目》): ‘Akebia Pith is white in color and cold in qi, bland in flavor and light in body; hence it enters the Tai Yin Lung channel, leads heat downward, and promotes urination.’
• Ri Hua Zi Ben Cao (《日华子本草》): ‘Brightens the eyes, reduces fever, hastens delivery, expels the placenta, and promotes lactation.’
• Ben Cao Bei Yao (《本草备要》): ‘Drains the Lung, promotes urination, promotes lactation; treats the five stranguries, reduces water edema, and eliminates vexation heat.’
• Kai Bao Ben Cao (《开宝本草》): ‘Governs expelling evil parasites, opens yin orifices, treats the five stranguries, eliminates water edema and urinary retention, and promotes lactation.’