于四逆汤方内。加入猪胆汁半合。余根据前法服。如无猪胆。以羊胆代之。
吐利发汗。脉平。小烦者。以新虚。不胜谷气故也。
内经曰。食入于阴。长气于阳。新虚不胜谷气。是生小烦。
伤寒阴阳易之为病。其人身体重。少气。少腹里急。或引阴中拘挛。热上冲胸。头重
不欲举。眼中生花。膝胫拘急者。烧 散主之。
大病新瘥。血气未复。余热未尽。强合阴阳得病者。名曰易。男子新病瘥。未平复。
而妇人与之交。得病。名曰阳易。妇人新病瘥。未平复。男子与之交。得病。名曰阴易。
以阴阳相感动其余毒。相染着。如换易也。其人病身体重。少气者。损动真气也。少腹里
急。引阴中拘挛。膝胫拘急。阴气极也。热上冲胸。头重。不欲举。眼中生花者。感动
之毒。所易之气。薰蒸于上也。与烧 散。以导阴气。
上取妇人中 。近隐处。剪烧灰。以水和服方寸匕。日三服。小便即利。阴头微肿。
则愈。妇人病。取男子 当烧灰。
张兼善云。易病之为合。阴阳感动余邪。而其人正气本虚。故能染着。同用烧 散。
以诱安正气。正气安。余邪自平矣。
大病瘥后。劳复者。枳实栀子汤主之。若有宿食者。加大黄。如博棋子大五六枚。
病有劳复。有食复。伤寒新瘥。血气未平。余热未尽。早作劳动。病曰名复劳复。病
热少愈而强食之。热有所藏。因其谷气留传。两阳相合而病者。名曰食复。劳复则热气
浮越。与枳实栀子豉汤以解之。食复则胃有宿积。加大黄以下之。
在四逆汤的方剂中加入半合猪胆汁。其余按照之前的方法服用。如果没有猪胆，可以用羊胆代替。
出现呕吐、腹泻并出汗后，脉象趋于平和，但仍有轻微烦闷不适，这是因为身体刚刚恢复虚弱，无法承受食物的运化之气所致。
《内经》说：“食物进入体内滋养阴分，进而助长阳气的生长。”身体新近虚弱，不能承受谷气，因此产生轻微的烦闷。
伤寒病中“阴阳易”这种病症，患者身体沉重，气短乏力，小腹部拘急疼痛，有时牵引至阴部痉挛抽搐，热气上冲胸部，头部沉重不想抬起，眼前发黑视物模糊，膝盖和小腿拘挛僵硬，应当用烧裈散来主治。
大病初愈，气血尚未恢复，余热未尽，此时强行进行房事而致病，称为“易”。男子大病初愈，身体未完全康复，就与女子发生性关系而致病，称为“阳易”；女子大病初愈，身体未完全康复，与男子发生性关系而致病，称为“阴易”。这是由于阴阳相互感应，残留的毒邪相互传染附着，如同更换衣物一样。患者身体沉重、气短，是因为真气受损扰动；小腹部拘急疼痛，牵引阴部痉挛，膝盖和小腿拘挛，说明阴气极度亏虚；热气上冲胸部，头部沉重不想抬起，眼前发黑，是因为被感动的毒邪和所交换的气机，熏蒸于上部所致。给予烧裈散，以引导阴气下行。
取妇人内裤（裈），靠近生殖器部位的部分，剪下后烧成灰，用水送服一方寸匕的药量，每日服用三次。服药后小便通畅，阴头轻微肿胀，即为痊愈。如果是女子患病，则取男子的内裤裆部烧灰服用。
张兼善说：所谓“易”病，是因为阴阳相互感应，残留的邪气侵袭，而患者正气原本虚弱，所以能够被传染附着。同样使用烧裈散，以诱导安固正气。正气安固，余邪自然平息。
大病初愈后因劳累而复发的，用枳实栀子汤主治。如果伴有宿食停滞，加大黄，大小如博棋子五六枚。
疾病复发有劳复和食复两种情况。伤寒病刚痊愈，气血未平，余热未尽，过早从事劳动而致病，叫做劳复；病热稍有好转就勉强进食，热邪有所藏留，因为谷气停留传变，新旧两阳相合而致病的，叫做食复。劳复则是热气浮越，用枳实栀子豉汤来解除；食复则是胃中有宿食积滞，加大黄来攻下。
Add half a *ge* (a traditional Chinese unit of volume) of pig bile to the *Sini Tang* (Four Reversal Decoction). Take the remaining medicine according to the previous methods. If pig bile is unavailable, substitute with sheep bile.
After vomiting, diarrhea, and sweating, if the pulse becomes calm but there is slight irritability, it is due to the body's recent deficiency being unable to withstand the qi of food digestion.
The *Neijing* (Inner Canon) states: "Food enters to nourish Yin, thereby generating Qi for Yang." The newly deficient body cannot withstand the grain qi, thus generating slight irritability.
In Shaoyin disease, the condition known as "Yin-Yang Exchange" presents with heavy body, shortness of breath, urgency and tightness in the lower abdomen, sometimes radiating to spasms in the genitalia, hot qi rushing up to the chest, heaviness of the head unwilling to be lifted, blurred vision or seeing spots, and stiffness/spasms in the knees and shins. This should be primarily treated with *Shao Kun San* (Burned Undergarment Powder).
After a major illness has just healed, blood and qi have not yet recovered, and residual heat remains. Forcing sexual intercourse and falling ill from this is called "Exchange." If a man, after recovering from a major illness but not yet fully restored, engages in intercourse with a woman and falls ill, it is called "Yang Exchange." If a woman, after recovering from a major illness but not yet fully restored, engages in intercourse with a man and falls ill, it is called "Yin Exchange." This occurs because Yin and Yang mutually resonate, allowing residual toxins to infect and adhere, similar to changing clothes. The patient's heavy body and shortness of breath indicate damage and disturbance of true Qi. The urgency/tightness in the lower abdomen, radiation to genital spasms, and knee/shin stiffness indicate extreme deficiency of Yin Qi. The hot qi rushing to the chest, heavy head unwilling to lift, and blurred vision are caused by the toxin of mutual resonance and the exchanged qi steaming upward. Administer *Shao Kun San* to guide the Yin Qi downward.
Take the part of a woman's undergarment near the genital area, cut it off, burn it to ash, and take one *cunbi* (a square-inch measure) mixed with water, three times daily. When urination becomes smooth and the glans penis swells slightly, the patient will recover. For women's illness, take the corresponding part of a man's undergarment, burn it to ash, and administer.
Zhang Jianshan stated: The so-called "Exchange" disease arises because Yin and Yang mutually resonate, allowing residual evil pathogens to invade, while the patient's healthy Qi is originally deficient, thus allowing infection and adherence. Using *Shao Kun San* similarly serves to induce and stabilize the healthy Qi. Once the healthy Qi is stabilized, the residual pathogens naturally subside.
For recurrence due to overexertion after a major illness heals, *Zhishi Zhizi Tang* (Immature Bitter Orange and Gardenia Decoction) is indicated. If there is retained food stagnation, add *Dahuang* (Rhubarb Root), five or six pieces the size of a Go stone.
Recurrence of illness can be due to labor (*Laofu*) or diet (*Shifu*). After Shaoyang disease has just healed, if blood and qi are not yet balanced and residual heat remains, engaging in early labor causes what is named *Laofu* (recurrence due to exertion). If the fever has slightly subsided but forced eating causes heat to be stored, and because grain qi lingers and transmits, causing two Yangs to combine and cause illness, it is named *Shifu* (recurrence due to diet). *Laofu* involves floating and overflowing heat, which is resolved with *Zhishi Zhizi Chidao Tang* (Immature Bitter Orange, Gardenia, and Fermented Soybean Decoction). *Shifu* involves retained accumulation in the stomach, which is purged downward by adding *Dahuang*.