Lu Gen (芦根) — Reed Rhizome | TCM Herb Guide

At a Glance

• Herb: Lu Gen
• Chinese name: 芦根 (Lú Gēn)
• Latin name: Phragmitis Rhizoma
• Nature: Cold
• Taste: Sweet
• Meridian: Lung / Stomach
• Category: Herbs that Clear Heat and Drain Fire
• Introduction: Lu Gen (芦根), Rhizoma Phragmitis, is the fresh or dried rhizome of Phragmites communis, the common reed growing in wetlands across China. Light, sweet, and cold, it clears heat from the lung and stomach while simultaneously generating fluids and relieving thirst — a gentle pairing that makes it safe for prolonged use. Modern research identifies polysaccharides and coixol with antipyretic, antiemetic, and diuretic properties.

Action

• Clears heat and generates fluids
• Relieves thirst and irritability
• Clears lung heat and expels pus
• Clears stomach heat and stops vomiting
• Promotes urination and clears heat via urine

Clinical Application

• Heat disease with thirst and fever: intense thirst, high fever, irritability — combines with Tian Hua Fen, Zhi Mu, Mai Dong
• Lung heat with cough, purulent sputum, or lung abscess — combines with Yi Yi Ren, Dong Gua Zi, Tao Ren
• Stomach heat with vomiting — used alone as fresh juice or combines with Zhu Ru, Sheng Jiang
• Febrile disease with measles, early-stage rash — promotes eruption
• Dysuria with heat — promotes urination, combines with Che Qian Zi

Precautions

• Dosage: 15–30 g dried; 60–120 g fresh in decoction
• Fresh form preferred when available — stronger fluid-generating effect
• Contraindicated in spleen-stomach deficiency cold
• Generally very safe — no significant toxicity or major incompatibilities
• Suitable for children and elderly with febrile illness

Formula

• Wei Jing Tang (苇茎汤): Lu Gen (Wei Jing), Yi Yi Ren, Dong Gua Zi, Tao Ren — clears lung heat, expels pus; classic formula for lung abscess
• Wu Zhi Yin (五汁饮): fresh Lu Gen juice, Pear juice, Water chestnut juice, Mai Dong juice, Lotus root juice — nourishes yin, generates fluids in febrile disease
• Yin Qiao San variant: adds Lu Gen to clear heat and generate fluids in wind-heat patterns

Combinations

• Reed Rhizome (芦根) + Trichosanthes Root (天花粉) + Ophiopogon Tuber (麦冬) → clear heat, generate fluids; thirst and dry mouth
• Reed Rhizome (芦根) + Bamboo Shavings (竹茹) + Fresh Ginger (生姜) → clear stomach heat, harmonize stomach; nausea and vomiting
• Reed Rhizome (芦根) + Job’s Tears Seed (薏苡仁) + Winter Melon Seed (冬瓜仁) → Wei Jing Tang (苇茎汤) basis: clear Lung heat, drain abscess; lung abscess and purulent sputum
• Reed Rhizome (芦根) + Mulberry Root Bark (桑白皮) + Scutellaria Root (黄芩) → clear Lung heat; cough with yellow sputum
• Reed Rhizome (芦根) + Imperata Rhizome (白茅根) + Plantain Herb (车前草) → clear heat, promote urination; hot lin and dysuria

Pharmacological Effects

• Antipyretic; antiemetic; diuretic; antioxidant; anti-inflammatory; mild analgesic; generates fluids
  • increases saliva
• detoxifies fish/crab poisoning; lung-protective

Classic Description

• Shen Nong Ben Cao Jing (《神农本草经》) [Reed Rhizome entry]: ‘Governs wasting-thirst, visiting heat, and stops excessive urination.’
• Ben Cao Gang Mu (《本草纲目》): ‘Reed Rhizome is sweet and cold; able to clear heat and generate fluids, stop thirst and eliminate vexation, stop vomiting, and promote urination.’
• Ming Yi Bie Lu (《名医别录》): ‘Treats rebellious stomach with vomiting and inability to eat, stomach heat, and internal heat from cold-damage — very effective.’
• Ben Cao Bei Yao (《本草备要》): ‘Drains heat, generates fluids and stops thirst, stops vomiting and eliminates vexation, promotes urination, and resolves pufferfish and fish-crab toxicity.’