Haichow Elsholtzia Herb

Chinese
香薷
Pinyin
Xiang Ru
Latin
Herba Elsholtziae

TCM Properties

Taste
acrid
Temperature
slightly warm
Channels
Lung, Stomach

Traditional Use

Primary Actions

  • Releases the Exterior and dispels Summer-Heat
  • Transforms Dampness and harmonizes the Middle Jiao
  • Promotes urination and reduces edema

Secondary Actions

  • Induces mild sweating for summer exterior patterns without sweating
  • Calms nausea, vomiting, and diarrhea from summer Damp-Cold

Classic Formulas

  • Xiang Ru San (香薷散) — Xiang Ru with Bai Bian Dou and Hou Po; classic formula for summer-cold exterior pattern with chills, fever, headache, and absence of sweating
  • Xin Jia Xiang Ru Yin (新加香薷饮) — updated Qing dynasty formula adding Lian Qiao and Jin Yin Hua; treats summer-heat with concurrent wind-cold exterior and interior dampness

Classical References

  • Ben Cao Gang Mu (Li Shizhen): 'Xiang Ru is the Ma Huang of summer — it releases the exterior through diaphoresis but acts specifically on Summer-Heat patterns'
  • Described as essential in summer as ephedra is in winter; critical distinction: must be taken cool — hot decoction causes vomiting

Modern Research

Active Compounds

  • Rosmarinic acid (predominant phenolic; highest in flowers)
  • Chlorogenic acid
  • Luteolin-7-O-glucoside (antiviral flavonoid)
  • Rutin
  • Thymol (essential oil component; antibacterial)
  • Carvacrol (essential oil; antibacterial)
  • p-Cymene

Studied Effects

  • Anti-inflammatory and antioxidant: ethanolic extracts show significant reduction in NO production and free-radical scavenging; rosmarinic acid and chlorogenic acid are principal active phenolics across all plant parts (PMID 32150805)
  • Antiviral: luteolin-7-O-glucoside inhibits Human Coronavirus OC43 replication with IC50 ~2 µM, approximately 2.5-fold more potent than the whole ethanol extract (IC50 ~5 µg/mL); supports traditional use in summer respiratory infections
  • Antibacterial: essential oil components thymol and carvacrol show inhibitory activity against Staphylococcus aureus, MRSA, and Escherichia coli

PubMed References

Safety & Interactions

Contraindications

  • Spontaneous sweating or profuse sweating — diaphoretic action will cause further fluid loss
  • Yin deficiency with Heat patterns
  • Heat-stroke with high fever and no exterior chill (pure interior Heat)

Cautions

  • Standard dose 3–9g; up to 15g in acute conditions
  • CRITICAL: must be drunk cool or at room temperature; hot decoction causes nausea and vomiting due to volatile oils
  • Add during final 5–10 minutes of decoction to preserve volatile oil activity
  • Use only when exterior pattern (chills, no sweating) is clearly present

Conditions