Deng Xin Cao (灯心草) — Rush Pith | TCM Herb Guide

At a Glance

• Herb: Deng Xin Cao
• Chinese name: 灯心草 (Dēng Xīn Cǎo)
• Latin name: Junci Medulla
• Nature: Slightly Cold
• Taste: Sweet / Bland
• Meridian: Heart / Lung / Small Intestine
• Category: Herbs that Drain Dampness (Diuretic Herbs)
• Introduction: Deng Xin Cao (灯心草), Medulla Junci, is the dried pith of Juncus effusus, the common rush, historically used as lamp wick material. One of the lightest and gentlest herbs in the materia medica, it clears heart heat, relieves irritability, and guides heat downward through urination. It is particularly suited for children with fever-related crying, insomnia, and irritability, and for mild heart-fire patterns in sensitive patients. Modern research confirms flavonoids with sedative and anti-inflammatory properties.

Action

• Clears heart heat and relieves irritability
• Promotes urination to drain heat
• Calms the spirit mildly
• Clears heat in the lung and stomach (mild)

Clinical Application

• Heart heat with irritability, insomnia, restlessness — combines with Zhu Ye, Lian Zi Xin, Mu Tong
• Children’s fever with crying and restlessness at night — uses alone as tea or combines with Deng Xin Cao charred
• Damp-heat dysuria with heart-fire — combines with Hua Shi, Zhu Ye
• Mouth sores from heart fire — combines with Huang Lian, Zhu Ye
• Summerheat with irritability and thirst in children

Precautions

• Dosage: 1–3 g in decoction (very light — use small amounts)
• Extremely gentle — one of the safest herbs; no significant toxicity or contraindications
• Contraindicated in cold patterns with clear urination from deficiency
• Charred form (Deng Xin Cao Tan): mildly astringent, used to stop bleeding from heat
• Ideal for children, elderly, and patients who need the gentlest heat-clearing action

Formula

• Dao Chi San (导赤散) variant: Deng Xin Cao replaces or augments Mu Tong as a gentler option
• Deng Xin Cao Yin (灯心草饮): Deng Xin Cao alone as tea — simple formula for childhood fever and irritability
• Ba Zheng San: includes Deng Xin Cao as a guiding herb to direct heat downward through urine

Combinations

• Rush Pith (灯心草) + Lophatherum Herb (竹叶) + Akebia Stem (木通) → clear Heart fire, promote urination; mouth sores, dark urine, and irritability
• Rush Pith (灯心草) + Plantain Herb (车前草) + Talcum (滑石) → clear heat, promote urination; hot lin and dysuria
• Rush Pith (灯心草) + Ophiopogon Tuber (麦冬) + Lotus Plumule (莲子心) → clear Heart heat, calm the shen; insomnia from Heart fire
• Rush Pith (灯心草) + Gardenia Fruit (栀子) + Coptis Rhizome (黄连) → clear Heart and Triple Burner fire; irritability and restlessness
• Rush Pith (灯心草) + Poria (茯苓) + Alisma Rhizome (泽泻) → drain dampness, calm the shen; restlessness with edema

Pharmacological Effects

• Diuretic; sedative
  • mild — reduces restlessness, treats infant night crying
• anti-inflammatory; antipyretic; antibacterial; antioxidant; inhibits platelet aggregation; cardioprotective

Classic Description

• Kai Bao Ben Cao (《开宝本草》): ‘Governs the five stranguries; decocted fresh and taken orally; using worn sedge mat decocted gives even better results.’
• Ben Cao Gang Mu (《本草纲目》): ‘Rush Pith descends Heart fire, stops bleeding, opens qi, disperses swelling, and stops thirst.’
• Ben Cao Bei Yao (《本草备要》): ‘Descends Heart fire, clears Lung heat, facilitates the Small Intestine, opens qi, stops thirst, eliminates vexation; treats the five stranguries, water edema, and infant night crying.’
• Ben Cao Cong Xin (《本草从新》): ‘Clears the Heart and descends fire, promotes urination and opens strangury; treats infant night crying and disperses warm sores.’