In the aftermath of a cold damage disease, the condition known as Yin-Yang Exchange (Yin Yang Yi) manifests with the patient experiencing heavy body sensations, shortness of breath, urgency and tightness in the lower abdomen, difficulty in urination, spasms in the genitalia, a sensation of heat rushing up to the chest, heaviness in the head making one reluctant to lift it, visual disturbances such as seeing spots before the eyes, and stiffness or cramping in the knees and shins. This should be primarily treated with Shao Kun San (Burned Underwear Powder).

This syndrome lacks both external and internal causes; originally, it is not a cold damage disease, yet it is prefixed with "cold damage." Investigating its etiology, there are no exterior symptoms like aversion to cold and fever, nor interior symptoms like stomach excess or spontaneous diarrhea. It arises from uncontrolled sexual desire, allowing residual pathogenic factors to exploit the void, transferring the affliction to an otherwise healthy person. Instantly, the essence, qi, spirit, and form of the entire body suffer the harm of lustful fire. Thus, the illness is not due to contracting cold damage, but rather due to the exchange of Yin and Yang energies.

One should not distinguish the naming solely based on male or female genders. Wherever pathogenic factors gather, the vital energy must be deficient. When Yin deficiency allows lascivious pathogens to invade, it results in shortness of breath and heat rushing up to the chest. With insufficient Qi to move the body, the head feels heavy and difficult to lift, and the whole body feels heavy. Pathogens invading the Yin regions cause genital spasms. Damage to the Chong and Ren vessels leads to lower abdominal urgency. Scattered spirit and mind cause visual hallucinations or spots. Agitation of sinews and bones results in knee and shin cramping. The disease originates in the Kidney, where toxins invade the water passages, causing urinary difficulty. It is unlikely that herbs of wood, earth, metal, or stone can cure this; instead, one must rely on the principle of Yin-Yang resonance to control it. This is why Kun (underwear) is used, seeking connection through intent.

Preparation and Administration of Shao Kun San (Burned Underwear Powder):
Take cloth from the area closest to the genitals of a woman, cut it off, burn it into ash, mix with water, and administer one Fang Cun Bi (a square-inch measure) per dose. Take three times daily. Once urination becomes smooth and the glans penis shows slight swelling, the patient will recover. If the patient is a woman, take the underwear of a man and burn it into ash for administration.

The Kun (underwear) serves as the guard of Yin and Yang for both men and women, where Yin and Yang breathe into each other, Qi gathers, and Essence converges. What guards the exterior can naturally clear the interior. For pathogens contracted invisibly, treatment employs tangible objects. Therefore, taking the cloth from the hidden area, burning it, and ingesting it utilizes the mutual induction of Form and Qi, accessing the hidden and subtle mechanisms, leading to immediate urination. Slight swelling of the glans indicates that turbid Yin descends through the lower orifice, allowing Clear Yang to ascend through the upper orifices. The lustful fire calms, and all symptoms vanish. Men take the woman's, and women take the man's, adhering to the principles of Yin-Yang exchange, the meaning of male-female conjunction of essence, and the investigation of things' nature. An extremely filthy substance becomes an extraordinarily effective prescription, as seen here.