The heart stores blood internally, which manifests externally as sweat; thus, sweat is the fluid of the Heart. The syndrome of spontaneous sweating (Zi Han) arises invariably from deficiency of both the Heart and Kidney. Therefore, when Yin is deficient, Yang invades, causing fever accompanied by spontaneous sweating; when Yang is deficient, Yin overcomes, causing cold extremities accompanied by spontaneous sweating. These are all caused by an imbalance where either Yin or Yang prevails.

Spontaneous sweating occurs at any time without external stimulus, worsens with movement, and belongs to Yang deficiency due to insecure interstices (Cou Li), governed by Stomach Qi. Thus, the Classics state: "Excess of Yang leads to body heat and absence of sweat." Humans rely on Defensive Qi (Wei Qi) to secure the exterior. When Defensive Qi is insecure, the exterior becomes deficient, leading to spontaneous sweating and the leakage of Body Fluids.

Sweat is the fluid of the Heart. If Heart Fire does not evaporate fluids, they will not transform into sweat; if Spleen Dampness flows downward, how can there be sweat? Only when Fire is constrained and steaming, causing Body Fluids to rise like mist, combined with insecure Defensive Qi, does it leak out as sweat. Therefore, in treating sweating disorders, if one exclusively employs formulas to secure the exterior without effect, it is because one fails to realize that Heart Fire is unsettled and Spleen Dampness has not descended. How can such sweating be restrained? The wise should examine this carefully.

A pulse that is fine and choppy, soggy and deficient and weak, all indicate spontaneous sweating. A pulse that is large and deficient, floating and soft also indicates spontaneous sweating. In Cold Damage (Shang Han), if both Yin and Yang pulses are tight, there should be no sweat. If spontaneous sweating occurs, it is termed "Loss of Yang" (Wang Yang) and is considered untreatable.

Sweat originating from the Heart is caused by Heat; sweat originating from the Spleen is due to Dampness rising; sweat leaking from the skin is due to insecure Defensive Qi. Therefore, clearing Heart Fire allows fluids to nourish internally and transform into Blood; harmonizing the Stomach allows fluids to circulate without rising recklessly; solidifying the interstices ensures Defensive Qi is abundant so fluids do not leak. Understanding these three principles completes the treatment of sweating disorders.

Spontaneous sweating due to Yang deficiency should be treated by tonifying Qi to protect the exterior; night sweating due to Yin deficiency should be treated by nourishing Yin to enrich the interior. Defensive Qi is Yang Qi; Nutritive Qi (Ying Qi) is Yin Blood. For treating Yang deficiency, herbs such as Renshen (Ginseng Radix et Rhizoma), Huangqi (Astragali Radix), Fangfeng (Saposhnikoviae Radix), and Guizhi (Cinnamomi Ramulus) are used. For treating Yin deficiency, herbs such as Danggui (Angelicae Sinensis Radix), Dihuang (Rehmanniae Radix), Huangbai (Phellodendri Cortex), and Huangjing (Polygonati Rhizoma) are used. To treat spontaneous sweating, Renshen and Huangqi are used, with a small addition of Guizhi and Fangfeng to reach the exterior. Hence it is said: "When Huangqi is paired with Fangfeng, its efficacy increases." For Yang deficiency, Fuzi (Aconiti Lateralis Radix Praeparata) may be slightly added to facilitate the action of Renshen and Huangqi. If Fire Qi steams upward and Stomach Dampness causes sweating, Liangge San (Cool the Chest Powder) is appropriate. If Heart Fire is restless causing irritability and sweating, Anshen Wan (Calming the Spirit Pill) or Qingxin Tang (Clear the Heart Decoction) are suitable. If Phlegm-Fluids remain in the chest causing sweating, Erchen Tang (Two-Cured Decoction) modified or Zhusha Guntan Wan (Cinnabar Rolling Phlegm Pill) are indicated.