Theory of diseases treated with decoction of Radix Puerariae

Woodcut illustration from an edition of 1833 (13th year of Daoguang reign period of Qing dynasty). The image and text give an account of the principles of diseases treated with decoction of Radix Puerariae (gegen tang), and the therapeutic effects of the individual ingredients of this remedy. Radix Puerariae decoction is made from cassia twig decoction with the addition of ephedra (mahuang) and Radix Puerariae. It is used to treat diseases simultaneously involving the taiyang channel and yangming channel. When wind-cold attacks the foot taiyang channel, the symptoms are headache, stiff neck and backache. Thus ephedra is used to help the cassia twig bring about a sweat, to nourish and protect the taiyang channel. When wind-cold attacks the foot yangming channel, the symptoms are sore eyes, a dry nose and pain along the brow ridge. These symptoms are treated with Radix Puerariae in conjunction with cassia twig, to eliminate malign Qi from the channel at the level of the muscles and bodily surface. The recipe also contains Chinese herbaceous peony (shaoyao), which is acidic in sapor, to harmonise nutrient Qi; Chinese dates (dazao), which are sweet,to assist protective Qi; fresh ginger, which is pungent, and has a dispersive, supportive and protective effect on the muscles; and liquorice, which is sweet, to harmonise the Centre and regulate the relationship between exterior and interior.

The stomach is the organ of the yangming channel. The yangming channel connects with the middle toe. NB The taiyang channel connects with the little toe. NB Liquorice, ginger; Chinese herbaceous peony (shaoyao) and dates are efficacious, in supplementing the benefits of cassia twig decoction, as shown in the illustration. When wind-cold is present in the taiyang channel,one has headache, a stiff neck and backache, because it runs along the whole channel, so ephedra and cassia are used to produce sweating. When wind-cold is present in the yangming channel, one has sore eyes, pain in the brow ridge, and a dry nose, so Radix Puerariaeis also used to produce sweating. The two channels meet at the jingming (Eye Bright) point and also above the ears; therefore they share much common ground.