Foxtail Sophora Root Classic Formulas … Natural Herb Library

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Clears heat and resolves toxin ... regional use of Ku Gan Cao centers on bitter-cold root material for damp-heat and toxic patterns showing inflamed skin, sore throat, or dysenteric bowel complaints.
Dries dampness and reduces itchy or weeping eruptions ... the root is used in folk and regional medicine for eczema, recurrent dermatitis, and other hot irritated lesions rather than as a gentle tonic.
Relieves painful swelling in hot obstructive states ... traditional use extends to sore lesions, inflamed tissue, and pain conditions where heat, toxin, or infection-like presentation dominates.

Regional decoctions pairing Ku Gan Cao with Huang Qin, Pu Gong Ying, or similar bitter detoxifying herbs ... used when damp-heat skin or throat inflammation is prominent.
Topical wash logic with other heat-clearing herbs ... a practical folk lane for eczema, recurrent dermatitis, or infected-looking skin lesions.
Heat-toxic dysentery pairings with herbs such as Huang Lian or Qin Pi ... a conservative regional strategy rather than a famous textbook formula.

Modern ethnopharmacology summaries note that multiple parts of Sophora alopecuroides have been used medicinally, but regional root use repeatedly clusters around dysentery, eczema, recurrent dermatitis, and furuncle-type lesions.
Because the indexed literature often pools root, aerial parts, seeds, and alkaloids together, conservative root-specific wording is more accurate than pretending the modern evidence is perfectly standardized.