Chan Chu

Chan Chu is the dried whole body of the toad, principally Bufo bufo gargarizans Cantor or Bufo melanostictus Schneider (Bufonidae), large nocturnal terrestrial amphibians widely distributed across East and Southeast Asia. Adult toads measure 7-12 cm in body length, with dry, warty, brown to grey dorsal skin and prominent parotoid glands behind the eyes that secrete a milky white venom containing bufadienolides (bufotalin, bufalin, cinobufagin) and biogenic amines. In classical TCM, the dried whole toad is considered acrid, cool, and toxic, used to resolve toxins, reduce swelling, dispel water, and treat carbuncles, scrofula, and edema. The white parotoid secretion, dried separately, constitutes the distinct drug Chan Su, used in small doses for shock, malignant boils, and certain cardiac conditions. Owing to the cardiotoxicity of bufadienolides, both Chan Chu and Chan Su are strictly dose-controlled in modern Chinese pharmacopoeial practice, and ingestion outside professional supervision can cause fatal arrhythmia.