In the diagnosis and treatment of Shanghan (Cold Damage), one must first observe the patient's complexion. The *Neijing* (Classic of Internal Medicine) states: "Sounds correspond to the Five Tones, complexions correspond to the Five Elements; when sound and color are consistent, one can then understand the diseases of the Five Zang organs." However, the Liver is green, its sound is a cry (Hu); the Lungs are white, its sound is weeping (Ku); the Heart is red, its sound is laughter (Xiao); the Spleen is yellow, its sound is singing (Ge); the Kidneys are black, its sound is groaning (Shen).

Furthermore, in the four seasons, complexions that generate each other are auspicious, while those that overcome each other are ominous. For example, green and red appearing in Spring, red and yellow in Summer, yellow and white in Late Summer, white and black in Autumn, and black and green in Winter—these are generating complexions. If Liver disease presents with a green complexion accompanied by white, Heart disease with red accompanied by black, Spleen disease with yellow accompanied by green, Lung disease with white accompanied by red, or Kidney disease with black accompanied by yellow, these all represent the overcoming relationship of the Five Elements and are difficult to treat.

Moreover, regarding the heat colors of the Five Zang organs manifesting on the face: Liver heat causes the left cheek to redden first; Lung heat causes the right cheek to redden first; Heart heat causes the forehead (Yan) to redden first; Spleen heat causes the nose tip (Zhuntou) to redden first; Kidney heat causes the chin (Yi) to redden first. As for a dark complexion, it indicates Yin Cold; a green complexion indicates Wind-Cold. Green and black indicate Wind, Cold, and pain; yellow and white indicate Dampness, Heat, and Qi stagnation; green and white indicate Wind, Qi stagnation, Cold, and pain. Generally, the appearance of black Qi on the face is mostly ominous and indicates severe illness. If the black Qi reveals brightness within the darkness, and the Zhuntou (nose tip) and Nianshou (bridge of the nose) are bright and moist, there is hope for life; if black and withered, there is death. This merely outlines the essentials. The *Neijing* holds that subtle diagnosis through the five colors can be observed with the eyes, and the *Nanjing* (Classic of Difficult Issues) states, "To know through observation is called divine," thus complexion must not be neglected.

In diagnosing Shanghan, one must first observe the complexion, then palpate the pulse, examine the symptoms, and integrate them to determine life and death, auspiciousness and inauspiciousness. Complexions of green, yellow, red, white, and black appear on the facial skin, with Qi resembling tangled threads or hair hidden beneath the skin. The Five Zang have five colors, and the Six Channels have six colors, all manifesting on the face corresponding to the Five Elements. Generating relationships are auspicious; overcoming relationships are ominous; nourished and moist complexions indicate life; withered and desiccated ones indicate death. According to the standards of Zhuntou, Nianshou, Yintang, and Renzhong, the presence of Qi color is key: moist and bright is auspicious, dark and dry is ominous. One should also comprehensively observe based on the principles of generation and overcoming in the four seasons. Herein, the essentials of the five-color Shanghan are listed below for reference:

Green belongs to Wood, governs Wind, Cold, and pain, and is the color of the Foot Jueyin Liver Channel. A green face and lips indicate extreme Yin. If tongue curling and testicular retraction occur, urgent warming is required. In cases of Jia-Yin Shanghan (Cold Damage involving the Yin channels), lower abdominal pain with a green face occurs. The *Neijing* states: "Green like kingfisher feathers indicates life; green like dead grass indicates death." Green with black or red indicates generation and life; green-white and dry indicates overcoming and death. Spleen disease presenting with green Qi is difficult to treat.

Red belongs to Fire, governs Heat, and is the color of the Hand Shaoyin Heart Channel. In Shanghan, seeing red involves distinctions among the Three Yang and One Yin. For instance, the Foot Taiyang Bladder Channel belongs to Water; cold makes it black, heat makes it red. The classics state: "A face uniformly and properly red indicates Yang Qi stagnation in the exterior due to incomplete sweating." Sweating should be induced. If the pulse is floating and rapid, with exterior heat and no sweat, and the face is red and lustrous, this matches the description. The classics state: "In Yangming disease, a face fully red means attack (purging) is contraindicated." 'He' implies connection; since exterior pathogens are unresolved, interior purging is forbidden. If Yangming interior excess exists, with aversion to heat but not cold, or tidal fever, constipation, delirium, and a red face, this is interior excess-heat, and purging is appropriate. If both exterior and interior are hot, with dry mouth and tongue, thirst, a large pulse, and a red face, but the interior is not yet solid, downward purging is temporarily contraindicated; instead, Renshen Baihu Tang (Ginseng White Tiger Decoction) should be used to harmonize. In Shaoyang channel disease, with heat half-exterior half-interior, a red face, and a wiry pulse, Xiaochaihu Tang (Minor Bupleurum Decoction) should be used to harmonize; purging is contraindicated. The classics state: "In Shaoyin disease, with diarrhea of undigested food, interior cold and exterior heat, and a red face, Si Ni Tang (Frigid Extremities Decoction) added with Congbai (Scallion Stalk) is indicated." This is extreme interior Yin-Cold forcing floating fire upward to the face, causing redness, which is not true heat. Failure to examine carefully and mistakenly administering cold-cooling agents will lead to death; caution is essential. Also, in Jia-Yin Shanghan with floating deficient Yang, the face may be red, but with cold feet and a deep pulse. Restlessness, red face, cold feet, deep pulse, and inability to drink water indicate extreme Yin; warming is indicated. In chronic illness with deficiency, afternoon redness of the malar eminences indicates Deficient Fire and should not be treated as Shanghan. However, the Qi of the Three Yang converges on the head and forehead: from the forehead to the vertex connecting to the brain is the Taiyang; from the forehead to the nose and face is the Yangming; from the temporal angle down into the ear and before/after the ear is the Shaoyang. Redness or swelling here helps differentiate. In Big Head Shanghan, understanding these parts is crucial. The *Neijing* states: Heart heat reddens the forehead first; Spleen heat reddens the nose first; Liver heat reddens the left cheek first; Lung heat reddens the right cheek first; Kidney heat reddens the chin first. Red with green or yellow indicates generation and auspiciousness; red with black indicates overcoming and inauspiciousness. The classics state: "Red like chicken comb indicates life; red like clotted blood indicates death." Red Qi in Zhuntou or Yintang, if withered, indicates death; if bright and moist, life. Lung disease with red Qi is difficult to treat.

Yellow belongs to Earth, governs Dampness, and is the color of the Foot Taiyin Spleen Channel. Bright yellow like an orange indicates Heat; dark and turbid yellow like smoked yellow indicates Dampness. Yellow with white or red indicates generation and auspiciousness; yellow with green indicates overcoming and inauspiciousness. Interior Yang Yellow like crab paste indicates life; like zhi shi (immature bitter orange) indicates death. If Zhuntou, Nianshou, or Yintang show bright and moist yellow Qi, the illness recedes with good omens; if dry and withered, death. Yellow eyes often precede recovery. In Late Summer, yellow-white is auspicious; yellow-green is ominous.

White belongs to Metal of the Lungs, governing Qi and Blood deficiency, and is the color of the Hand Taiyin Lung Channel. Liver disease presenting with white is difficult to treat. The *Neijing* states: "White like pig fat indicates life; white like withered bone indicates death." White in Yintang or Nianshou, if withered, is ominous; if bright and moist, auspicious. White with black or yellow indicates generation and auspiciousness; white with red indicates overcoming and inauspiciousness. A pale, spiritless face in Shanghan results from excessive sweating or blood loss.

Black belongs to Water, governs Cold and pain, and is the color of the Foot Shaoyin Kidney Channel. Black with white or green indicates generation and auspiciousness; black with yellow indicates overcoming and inauspiciousness. The *Neijing* states: "Black like crow feathers indicates life; black like soot indicates death." Black Qi in Zhuntou, Nianshou, or Yintang, if withered, indicates death; if bright and moist within the black, life. Black Qi extending from the eye corners (Yuwei) into the Taiyin area indicates death; Black Qi entering from Faleng or Renzhong indicates death. Withered black Qi in ears, eyes, mouth, or nose indicates death. Bright and moist Zhuntou or Minggong indicates life; withered and dark indicates death. Heart disease with black Qi in the head indicates death. Hua Tuo stated: "When patient's facial features match, it is auspicious; when they do not match, it is ominous." Examples of mismatch include green face with white eyes, red face with green eyes, yellow face with green eyes, red face with white eyes, white face with black eyes, black face with white eyes, white face with green eyes—all inauspicious. Matching features, such as both face and eyes being green or red, are auspicious.