Capillary Wormwood (Yin Chen) Classic Formulas

Primary Actions

Clears Damp-Heat and resolves jaundice - the classic chief herb for bright yellow Yang-type jaundice with dark urine, abdominal fullness, greasy coating, and Liver-Gallbladder damp-heat, especially when paired with Zhi Zi and Da Huang.
Drains Damp-Heat from the Liver and Gallbladder while promoting urination - used for dysuria, edema, bitter taste, chest oppression, and febrile damp-heat patterns that need both biliary and urinary drainage.
Relieves exterior-level damp-heat - selected for warm-damp or summer-damp presentations with fever, body aches, poor appetite, and oppression of the chest and epigastrium.
Clears Damp-Heat from the skin - extended to eczema, urticaria, oozing sores, and itchy lower-body lesions when Damp-Heat manifests in the exterior tissues.

Yin Chen Hao Tang (茵陈蒿汤) - from Shang Han Lun, the classic three-herb jaundice formula in which Yin Chen is the chief herb clearing Damp-Heat from the Liver, Gallbladder, intestines, and urine.
Gan Lu Xiao Du Dan (甘露消毒丹) - epidemic damp-heat formula using Yin Chen to vent Damp-Heat and reduce jaundice, fever, and chest oppression.
Zhen Gan Xi Feng Tang (镇肝熄风汤) - a later formula where Yin Chen serves as an assistant to smooth Liver heat and support downward drainage in complex Liver-Yang excess patterns.

Shen Nong Ben Cao Jing is repeatedly cited in later reviews as the earliest classic source for Yin Chen Hao's use in jaundice and hepatic disorders.
The long-standing aphorism 'in the second month it is Yin Chen, in the fifth month it is firewood' highlights the classical insistence on young spring material for best activity.
IMPORT NOTE: the source stub listed the pinyin as Chen Hao, but mainstream TCM sources identify the standard drug here as Yin Chen, with Yin Chen Hao preserved separately as the fuller synonym in herb #186.