The Herb Cabinet 本草

柴胡 chái hú

Bupleurum chinense · bupleurum root

Slightly cool Bitter · Pungent LiverGallbladder

“The unknotter. When qi is stuck — in the flanks, in the temper, in the space between one sigh and the next — this is the root the great formulas are built around.” — Lao Xinglin

What the tradition says

Few roots have chaired more famous prescriptions. Chai hu's signature act is to course the liver and relieve constraint — to restore movement where stress and emotion have knotted the qi — which makes it chief of Xiao Yao San and of the whole Bupleurum family of formulas from the Shang Han Lun^[1]. The tradition also credits it with resolving lingering "half-exterior, half-interior" illness — the alternating chills and fever of a battle fought at the threshold — and with raising clear yang when what should lift has sagged^[1].

What the research says

Preclinical studies report anti-inflammatory, antiviral, and immune-modulating properties for bupleurum's saikosaponins, but human trials are lacking — the clinical case rests on the formulas, not the lone root^[2]. (For the best-studied of those, see the Xiao Yao San evidence.)

Where to be careful

• Dose matters: case reports describe liver damage with excessive

doses of bupleurum^[2] — an irony the tradition would appreciate, and a reason it is always dosed modestly inside balanced formulas.

• Drug metabolism: it may interact with drugs handled by several CYP

enzymes (2C9, 2D6, 3A4 among them)^[2].

• The tradition's own note: its rising, dispersing nature can aggravate

yin-deficient heat — the flushed, depleted, night-sweating picture^[1].

In the pharmacy

The thin, hard root of Bupleurum chinense — "firewood hu," as the name has it. Vinegar-fried chai hu leans harder into liver-soothing; the raw root into lifting and releasing^[1].

Reviewed 2026-08-25