If a Shanghan (Cold Damage) disease is not treated with sweating methods to release the exterior, it may transform into Huhu disease (a condition characterized by oral and genital ulcers). The term "Huhu" implies a state of hesitation and indecision, reflecting the patient's fluctuating mental state. This occurs because the stomach lacks food, leaving the intestines empty; "three worms" (a general term for parasites) seek nourishment by gnawing on the internal organs, leading to sores in the lips and mouth. Sores on the upper lip indicate that worms are eating the viscera, termed "Hu" (Confusion); sores on the lower lip indicate that worms are eating the anus, termed "Hu" (Fox). Clinical manifestations include dry teeth, hoarseness, aversion to food, facial complexion alternating between red, white, and black, white tongue coating, black lips with ulcers, heaviness in the four limbs, and somnolence. If throat dryness and severe oral ulcers occur, the prognosis is poor and may lead to death.

[Clear Heat] Huanglian Xijiao Tang (Coptis and Rhinoceros Horn Decoction).
[Cool Blood] For symptoms of lip sores and hoarseness, use Taoren Tang (Peach Kernel Decoction).
[Kill Parasites] Apply Xionghuang Ruisan (Realgar Acute Powder) as a paste, inserted into the anal canal.

Generally, patients suffer from insomnia, but those with Shanghan often exhibit excessive sleepiness. There are four explanations for this: First, when Taiyang disease (Disease of the Bladder and Small Intestine channels) is about to resolve, excessive sleep occurs, indicating the recovery of Shen (Spirit); Second, in Shaoyin disease (Disease of the Heart and Kidney channels), the pulse is deep and fine, and the patient desires only to sleep, indicating clouded Shen; Third, in Fengwen (Wind-Warmth) disease, if the condition lingers unresolved, excessive sleep also occurs; Fourth, in Huhu disease, heaviness in the four limbs, preference for sleep, and sores on the upper and lower lips indicate a vague or unsettled Shen. Generally speaking, when Yang Qi is deficient and Yin Qi is abundant, the eyes close and sleep ensues. Thus, excessive sleepiness indicates that pathogenic factors have transmitted to the Yin aspect rather than remaining in the Yang aspect. Drowsiness with closed eyes reflects the closing function of Yin; silence reflects the quiet nature of Yin.

[Harmonize] For Taiyang disease with a fine pulse and excessive sleepiness, where exterior symptoms have resolved, use Xiaochaihu Tang (Minor Bupleurum Decoction).
[Warm] For Shaoyin disease where the pulse at the cun, guan, and chi positions is uniformly deep and fine, and the patient desires only to sleep, this is a Shaoyin syndrome, treated with Sini Tang (Frigid Extremities Decoction). For Fengwen disease, where the Yang pulse is floating and slippery, the Yin pulse is soft and weak, accompanied by profuse sweating or persistent high body heat after sweating, along with wheezing and excessive sleepiness, this is Fengwen disease, treated by Weirui Tang (Polygonatum Decoction).

When Yang is abundant and Yin is deficient, insomnia occurs day and night. Night is governed by Yin; when Yin Qi is strong, the eyes close and rest is peaceful. If Yin is overcome by Yang, restlessness and insomnia persist throughout the night. This is referred to as "Yin deficiency competing with the night." Generally, insomnia in Shanghan is due to Heat. When various Yang meridians converge and Yin-Yang harmony is not restored, insomnia results. High fever with unclear spirit also causes insomnia; severe purging damaging blood, since the Heart governs blood, also causes insomnia. After recovery, residual heat combining with Yang Qi while Yin Qi has not yet recovered also leads to insomnia.

[Harmonize] For insomnia occurring day and night after vomiting or purging, use Suanzaoren Tang (Ziziphus Seed Decoction). For post-vomiting/purging mental restlessness, vexation, and insomnia due to deficiency, use Zhizi Chi Tang (Gardenia and Fermented Soybean Decoction).
[Clear Heat] For high fever, dry retching, delirium, and insomnia, use Huanglian Jiedu Tang (Coptis Detoxification Decoction). For Shaoyin disease lasting more than two or three days, with heart vexation and insomnia, use Huanglian Jizi Tang (Coptis and Egg Yolk Decoction).
[Replenish Fluids] After profuse sweating in Taiyang disease, if stomach dryness causes insomnia and thirst, provide water in small amounts frequently.
[Separate and Drain] For thirst and insomnia following purging, use Zhuling Tang (Polyporus Decoction). For insomnia with a floating pulse and difficult urination, use Wuling San (Five-Ingredient Powder with Poria).
[Warm] For insomnia following purging and subsequent sweating, without exterior signs but with a deep pulse, use Ganjiang Fuzi Tang (Dried Ginger and Aconite Decoction).