（即阴阳易也，以大病瘥后，男女相易而复作也）
易 谓男女相易则为阴阳易，不易自病谓之女劳复，以其内损真气，外动邪
热，真虚邪盛，不可治矣。
其证身体重少气（乃损真气也），小腹里急，引阴中拘挛，膝胫拘急（阴气极也），热上
冲胸，头重不欲举，眼中生花（乃所易之毒瓦斯上蒸也）。
舌卷卵缩（附）
舌卷卵缩，谓肝热也。
目瞪，伤寒目瞪口噤，不省人事，此中风 ，宜开关吐痰，痰退眼开，观证治之。
伤寒过经，疾退无热，人困不语，脉和目瞪，下虚戴阳故也。
阳毒不解，热伏太阳，故使目瞪，六脉弦劲，渐作鱼口，气粗者死。
发斑，热炽也。
舌焦黑，面赤，阳毒也。治宜阳毒升麻汤、白虎加参汤。
冬月大暖，至春发斑，阳脉浮数，阴脉实大，温毒也，治宜承气黄连汤。
两感，一日双传，脉沉而大；二日沉长；三日沉弦，在里证宜四逆汤，表证桂枝汤也。
(This is Yin-Yang Yi [Yin-Yang Exchange], referring to the recurrence of disease after a major illness has subsided, caused by sexual intercourse between men and women.)
"Yi" [Exchange] refers to the transmission of disease through sexual intercourse, termed "Yin-Yang Yi"; if one falls ill spontaneously without intercourse, it is termed "Nü Lao Fu" [Female Labor Recurrence]. This occurs because the true Qi [Vital Energy] is damaged internally, and pathogenic heat is stirred externally. With deficiency of true Qi and excess of pathogenic factors, it is considered incurable.
The symptoms include heaviness of the body and shortness of breath (indicating damage to true Qi), urgency and tension in the lower abdomen radiating to spasmodic contraction of the genitalia, and stiffness and tension in the knees and calves (indicating extreme depletion of Yin Qi). There is also a sensation of heat rushing up to the chest, a heavy head unwilling to be lifted, and visual disturbances such as seeing spots or flowers (caused by the steaming upward of the exchanged toxic vapors).
Tongue Retraction and Testicular Contraction (Note):
Tongue retraction and testicular contraction indicate Liver Heat.
Staring Eyes:
In Shanghan [Cold Damage], staring eyes with locked jaw and loss of consciousness indicate Zhongfeng [Wind Stroke]. The treatment should focus on opening the orifices and expelling phlegm; once the phlegm recedes and the eyes open, treat according to the syndrome.
After the course of Shanghan has passed, with the disease retreating and no fever, if the patient is lethargic, unable to speak, has a harmonious pulse but stares with wide eyes, this is due to deficiency in the lower jiao [Lower Burner] and floating deficient Yang [Dai Yang].
If Yang Du [Yang Toxin] does not resolve, and heat lies concealed in the Taiyang [Greater Yang] channel, causing staring eyes, with wiry and stiff pulses in all six positions, progressing to fish-mouth anus [anal fissure] and coarse breathing, death ensues.
Eruption of Macules [Fa Ban]:
Indicates blazing heat.
Blackened Scorched Tongue and Red Face:
Indicates Yang Du [Yang Toxin]. Treatment should utilize Yang Du Shengma Tang [Yang Toxin Corydalis Decoction] or Baihu Jia Renshen Tang [White Tiger Decoction plus Ginseng].
If winter is unusually warm, leading to macule eruption in spring, with floating and rapid pulses at the cun [distal] position and solid and large pulses at the chi [proximal] position, this indicates Wendu [Warm Toxicity]. Treatment should utilize Chengqi Huanglian Tang [Chengqi Coptis Decoction].
Huo Huo [Huohuo Disease]:
Characterized by white coating on the tongue, bluish lips, ulcers in the mouth or genitals, heaviness in the four limbs, mental restlessness with a tendency to sleep, caused by the loss of body fluids/sweat.
Hui Jue [Roundworm Cold Reversal]:
Caused by cold in the zang organs [Viscera]. Treatment should utilize Wu Mei Wan [Mume Pill] or Lizhong Wan [Regulate the Middle Pill].
Liang Gan [Double Transmission]:
On the first day, both channels are affected simultaneously, with a deep and large pulse; on the second day, a deep and long pulse; on the third day, a deep and wiry pulse. For interior syndromes, Sini Tang [Counterflow Decoction] is indicated; for exterior syndromes, Guizhi Tang [Cinnamon Twig Decoction] is indicated.
Sore Throat:
For Shaoyin [Lesser Yin] with heat, Huanglian Longgu Tang [Coptis and Dragon Bone Decoction] is indicated. For Shaoyin without heat, Sini San [Counterflow Powder] is indicated. For oral ulcers, honey-soaked Coptis juice is indicated.
Body Pain:
For Yang [Exterior/Excess] patterns, Mahuang Guizhi [Ephedra and Cinnamon Twig formulas] are indicated. For Yin [Interior/Deficiency] patterns, Zhenwu Tang [True Warrior Decoction] is indicated. For Dampness, Shu Fu Wuling [Atractylodes and Aconite combined with Five-Ingredient Poria Decoction] is indicated.
Difficulty in Urination with Frequency:
For Heat, Wuling Chengqi [Five-Ingredient Poria combined with Chengqi formulas] is indicated. For Dampness, Ginger and Aconite are indicated. For Cold-Heat complex, Chaihu Guizhi Jiangxin Ganjiang Tang [Bupleurum, Cinnamon Twig, Pinellia, and Dried Ginger Decoction] is indicated. For significant frequency, Ganjiang Gancao Shaoyao Tang [Dried Ginger, Licorice, and Peony Decoction] or Chengqi-type formulas are indicated.