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(Transition from Taiyang to Yangming)
In individuals with robust Yang, if exterior cold is contracted while interior heat exists, Da Qing Long Tang (Great Blue Dragon Decoction) is used. Once the exterior cold is resolved, if the interior heat remains excessive, Bai Hu Tang (White Tiger Decoction) is employed to clear Lung Metal (the organ system associated with metal in Five Phase theory). By clearing Lung Metal, stomach heat dissipates, preventing the progression to Yangming disease syndromes. Regarding thirst caused by Yang deficiency after sweating, Ren Shen (Ginseng Root) is added to Bai Hu Tang to cool Lung Metal, tonify Qi, generate fluids, and transform water. Its efficacy in clearing vexation and quenching thirst surpasses human ingenuity, resembling heavenly craftsmanship; the formulation and principles are divine and difficult to trace. However, although Bai Hu Tang syndromes appear under Shang Han (Cold Damage) chapters, they often originate from Zhong Feng (Wind Strike). For instance, after taking Gui Zhi Tang (Cinnamon Twig Decoction), profuse sweating occurs, followed by severe vexation and unrelenting thirst with a surging pulse; this is treated with Bai Hu Jia Ren Shen Tang (White Tiger Decoction plus Ginseng Root), clearly indicating a wind pathogen syndrome. Zhong Feng frequently transmits to Yangming; thus, the Bai Hu Tang syndrome represents the initial stage of Cheng Qi Tang (Order the Qi Decoction) syndrome, specifically the early phase of Qi-level heat.

In Shang Han, if the pulse is slippery and there is cold extremities (Jue), it indicates interior heat, treated with Bai Hu Tang.
Cold extremities with a slow and choppy pulse indicate interior cold Jue; however, a slippery pulse indicates interior heat. This is because dry-heat stagnates internally, invading Yin positions, causing Yin Qi to float outward to the limbs, resulting in cold extremities despite a slippery pulse. In Bai Hu Tang, Shi Gao (Gypsum Fibrosum) clears Lung Metal and reduces fever; Zhi Mu (Anemarrhenae Rhizoma) moistens dryness and drains fire; Gan Cao (Licorice Root) and Jing Mi (Oryza Sativa) tonify the Middle Jiao, transform Qi, generate fluids, and relieve thirst. In individuals with naturally strong Stomach Yang, if Yin deficiency leads to hyperactive fire, external contraction causes meridian heat to steam internally, consuming body fluids, which may lead to Yangming Fu-organ excess syndromes. However, before Stomach fire becomes extreme, Lung fluids are often injured first. Upon observing thirst, Bai Hu Tang is used initially to cool Lung Metal, drain heat, nourish water, and clear diaphragmatic heat. This rectifies the heat, preventing it from entering the Stomach and causing the harm of vexation, heat, and loss of Yin. The Bai Hu Tang syndrome is the precursor to the future Da Cheng Qi Tang (Great Order the Qi Decoction) syndrome, but interior heat is not yet solidified; it is also the state following the Da Qing Long Tang syndrome where exterior cold has been resolved. Since exterior cold is resolved, Ma Huang (Ephedrae Herba) is omitted; since interior heat is not yet solidified, Mang Xiao (Natrii Sulfas) and Da Huang (Rhei Radix et Rhizoma) are omitted.

Shi Gao (Gypsum Fibrosum) - 1 jin
Zhi Mu (Anemarrhenae Rhizoma) - 6 liang
Gan Cao (Licorice Root) - 2 liang
Jing Mi (Oryza Sativa) - 6 he

The above four ingredients are boiled in 10 sheng of water until the rice is cooked and the decoction is ready. Strain and take 1 sheng warm, three times daily.

In Shang Han, if the pulse is floating and slippery, it indicates interior heat and exterior cold, treated with Bai Hu Tang.
This clarifies the implicit meaning of the previous chapter: a slippery pulse indicates interior heat; cold extremities indicate exterior cold. Here, cold extremities are not mentioned because a floating and slippery pulse already indicates exterior cold binding and interior heat stagnating, making inquiry into limb temperature unnecessary. If interior heat were to erupt outward, the pulse would become full and slow, no longer floating and slippery. A floating and slippery pulse is a sign of Yang Qi being constrained and blocked. The "exterior cold" here refers to the outward floating of Yin Qi, not an invasion of external cold pathogens. Otherwise, if exterior cold were unresolved, there would be no rationale for using Bai Hu Tang.