（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。
（这就是阴阳易，指大病初愈后，男女交合导致疾病复发）
“易”是指男女交合导致疾病相互传染，称为“阴阳易”；如果不交合而自行发病，则称为“女劳复”。这是因为体内真气受损，体外邪热被扰动，导致正气虚弱而邪气亢盛，属于难以治疗的病症。
其症状表现为身体沉重、气短（这是真气受损的表现），小腹部拘急疼痛，牵引阴部痉挛收缩，膝盖和小腿拘挛紧急（这是阴气极度亏损的表现），热气上冲胸部，头部沉重不想抬起，眼中视物模糊或见花（这是所交换的毒瓦斯向上熏蒸所致）。
舌体卷缩、睾丸上缩（附注）：
舌体卷缩、睾丸上缩，指的是肝经有热。
眼睛瞪大直视：
伤寒病出现眼睛瞪大、口噤不开、不省人事，这是中风的症状，应当采用开窍吐痰的方法治疗，痰退后眼睛睁开，再根据证候进行治疗。
伤寒病经过传变周期后，疾病消退且无发热，人困倦不能说话，脉象平和但眼睛瞪大直视，这是由于下焦虚损、虚阳上浮（戴阳）的缘故。
阳毒之邪不解，热邪伏留于太阳经，导致眼睛瞪大直视，六脉弦硬有力，逐渐出现鱼口状（肛门裂开如鱼口），呼吸粗重者预后不良，会死亡。
发斑：
是热势炽盛的表现。
舌苔焦黑、面色红赤：
这是阳毒的表现。治疗适宜用阳毒升麻汤、白虎加人参汤。
冬季气候异常温暖，到了春季发生发斑，脉象阳部浮数、阴部实大，这是温毒的表现，治疗适宜用承气黄连汤。
狐惑病：
舌上有白苔，嘴唇青紫，口腔或前后二阴有溃疡疮疡，四肢沉重，神情恍惚喜欢嗜睡，因津液耗失所致。
两感病：
第一天双经同传，脉象沉而大；第二天脉象沉长；第三天脉象沉弦。如果是里证适宜用四逆汤，如果是表证适宜用桂枝汤。
咽痛：
有少阴经热证的，适宜用黄连龙骨汤。有少阴经无热证的，适宜用四逆散。有口腔溃疡的，适宜用蜂蜜浸泡黄连汁含服。
身痛：
有阳证（表实）的，适宜用麻黄汤、桂枝汤。有阴证（里虚寒）的，适宜用真武汤。有湿邪的，适宜用术附五苓散（白术、附子配合五苓散）。
小便不利且频数：
有热证的，适宜用五苓散合承气汤；有湿证的，适宜用干姜、附子；有寒热错杂的，适宜用柴胡桂枝干姜汤。频数明显的，适宜用干姜甘草芍药汤、承气汤类方剂。
(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.