呕者，有声无物；吐者，吐出食物也。呕者有寒有热，吐则皆因胃寒也。凡呕而发热烦闷者，
邪热为呕也。
呕而吞酸冷咽，涎沫FS FS 一者，寒邪为呕也。大抵伤寒表邪将传入里，里气相逆则为呕，是以半表
半里之邪，其证多呕，若邪全在表，无是证也。凡邪在半表半里者，和之散之，气逆者顺之，有痰
者降之，热者清之，寒者温之。《千金》云∶呕家多服生姜，此是呕家圣药。然呕家虽有阳明证，
不可攻之，盖其气逆在上，而邪未入腑，本非胃实证也。气逆于上而攻其下，下虚则逆气乘之，势
必大危，若脉微弱者，乃为尤甚。
凡伤寒三阳传毕，三阴当受邪矣，若其人反能食而不呕，此为邪不入阴，是知邪之传里者，乃
致为呕也。观干姜附子汤证治云∶不呕不渴者，为里无热。十枣汤证治云∶干呕，短气，汗出，不
恶寒者，此表解里未和也。即此观之，则凡呕者，知为里证，而兼烦渴者，方为内热也。
仲景《论》曰∶食谷欲呕者，属阳明也，吴茱萸汤主之。得汤反剧者，属上焦也。曰∶少阴病
，吐痢，手足厥冷，烦躁欲死者，吴茱萸汤主之。
《论》曰∶病患脉数，数为热，当消谷引饮，而反吐者，此以发汗，令阳气微，膈气虚，脉乃
数也。数为客热，不能消谷，以胃中虚冷，故吐也。东垣曰；邪热不杀谷，故热邪在胃则不食。
《论》曰∶阳明病不能食，攻其热必哕，所以然者，胃中虚冷故也。以其人本虚，故攻其热必
哕。若胃中虚冷不能食者，饮水则哕。若膈上有寒饮，干呕者，不可吐也，急温之，宜四逆汤。
《论》曰∶伤寒哕而腹满，视其前后，知何部不利，利之则愈。治哕诸法，详呃逆门。
呕吐，有声而无物吐出；吐，是指将食物吐出。呕既有寒证也有热证，而吐则多因胃寒所致。凡是呕吐且伴有发热、心烦闷乱的症状，是邪热导致的呕吐。
呕吐并伴有吞酸、冷咽感及涎沫者，是寒邪导致的呕吐。大抵伤寒病中，表邪即将传入里部时，里气上逆就会发生呕吐，因此半表半里的邪气，其症状多见呕吐；若邪气完全在表，则不会出现这种症状。凡邪气在半表半里者，应当和解发散；气机上逆的，应当顺降气机；有痰的，应当降痰；热证的，应当清热；寒证的，应当温阳。《千金方》说：呕吐患者应多服用生姜，这是治疗呕吐的圣药。然而，呕吐患者即使有阳明病的证候，也不可攻下，因为其气机上逆于上，且邪气尚未入腑，本来就不是胃实证。气机上逆于上却去攻伐下部，会导致下部虚弱，逆气乘虚而入，病情势必非常危险，如果脉象微弱，情况就更为严重。
凡是伤寒三阳经的病传变完毕，三阴经应当受邪了，如果病人反而能进食且不呕吐，这说明邪气没有传入阴经，由此可知，邪气传入里部才会导致呕吐。观察干姜附子汤的证治条文说：“不呕吐、不口渴的，说明里没有热。”十枣汤的证治条文说：“干呕、气短、出汗、不恶寒的，这是表证已解但里气不和。”从这些可以看出，凡是呕吐的，都知道是里证，只有兼见心烦口渴的，才是内热证。
张仲景《伤寒论》说：“进食后想要呕吐的，属于阳明病，用吴茱萸汤主治。服药后病情反而加重的，属于上焦病。”又说：“少阴病，出现呕吐腹泻，手足冰冷，烦躁欲死的，用吴茱萸汤主治。”
《伤寒论》说：“病人脉数，数脉主热，应当消化食物且想喝水，反而呕吐的，这是因为发汗过度，导致阳气微弱，膈间气虚，脉才表现为数。这里的数是客热（假热），不能消化食物，因为胃中虚冷，所以发生呕吐。”李东垣说：“邪热不能腐熟水谷，所以热邪在胃就会导致不想吃东西。”
《伤寒论》说：“阳明病不能进食，如果攻其热邪必定会出现呃逆，之所以这样，是因为胃中虚冷。因为病人本身体质虚弱，所以攻其热邪必定导致呃逆。如果胃中虚冷不能进食，喝水也会引起呃逆。如果膈上有寒饮，出现干呕的，不可使用涌吐法，应当紧急温阳，适宜用四逆汤。”
《伤寒论》说：“伤寒出现呃逆且腹部胀满，查看前后二便，知道哪一部分不通利，通利它就能痊愈。”治疗呃逆的各种方法，详见“呃逆”章节。
Vomiting (Ou) refers to retching with sound but no matter expelled; spitting (Tu) refers to the expulsion of food. Vomiting can be caused by either cold or heat, whereas spitting is generally due to stomach cold. When vomiting is accompanied by fever, irritability, and oppression, it is caused by pathogenic heat.
When vomiting is accompanied by acid regurgitation, a sensation of cold in the throat, and excessive salivation, it is caused by pathogenic cold. Generally, when exterior pathogens in Shanghan (Cold Damage) are about to transmit inward, the reversal of interior Qi leads to vomiting. Therefore, pathogens located at the half-exterior half-interior level often present with vomiting; if the pathogen remains entirely in the exterior, this symptom does not occur. For pathogens at the half-exterior half-interior level, harmonization and dispersal are indicated; for reversed Qi, descending is indicated; for phlegm, resolving phlegm is indicated; for heat, clearing heat is indicated; for cold, warming is indicated. The *Qianjin Fang* states: "Patients with vomiting should take fresh ginger frequently; this is the sacred medicine for vomiting." However, even if a patient with vomiting presents with Yangming syndrome patterns, purgation must not be used. This is because the Qi is reversed upward and the pathogen has not yet entered the fu organs, so it is fundamentally not a stomach excess pattern. Attacking the lower body when Qi is reversed upward will cause deficiency in the lower jiao, allowing the reversed Qi to exploit this weakness, leading to severe danger. If the pulse is faint and weak, the situation is even more critical.
After the transmission through the three yang meridians in Shanghan is complete, the three yin meridians should be affected. If the patient can eat and does not vomit, it indicates that the pathogen has not entered the yin level. Thus, we know that vomiting results from the pathogen transmitting to the interior. Observing the treatment principles of Ganjiang Fuzi Tang (Dried Ginger and Aconite Decoction), it states: "No vomiting and no thirst indicate no heat in the interior." Observing the treatment principles of Shizao Tang (Ten Jujube Decoction), it states: "Dry retching, shortness of breath, sweating, and absence of aversion to cold indicate that the exterior is resolved but the interior is disharmonious." From these, we can deduce that vomiting generally indicates an interior pattern; only when accompanied by irritability and thirst does it indicate internal heat.
Zhang Zhongjing's *Shanghan Lun* states: "Those who wish to vomit after eating belong to the Yangming stage, treated with Wuzhuyu Tang (Evodia Decoction). If symptoms worsen after taking the decoction, the pathology belongs to the upper jiao." It also states: "In Shaoyin disease, characterized by vomiting and diarrhea, cold limbs, and extreme irritability, Wuzhuyu Tang (Evodia Decoction) is indicated."
The *Shanghan Lun* states: "If a patient has a rapid pulse, which indicates heat, they should digest food well and desire drinking water. If they instead vomit, it is because excessive sweating has depleted Yang Qi, causing Qi deficiency in the diaphragm, resulting in a rapid pulse. This rapid pulse represents 'guest heat' (false heat), which cannot digest food; vomiting occurs because of cold deficiency in the stomach." Li Dongyuan stated: "Pathogenic heat fails to transform grain; thus, when pathogenic heat resides in the stomach, appetite is lost."
The *Shanghan Lun* states: "In Yangming disease, if the patient cannot eat, attacking the heat will inevitably lead to hiccups (Yue). This is because of cold deficiency in the stomach. Since the person is inherently deficient, attacking the heat will cause hiccups. If cold deficiency in the stomach prevents eating, drinking water will also induce hiccups. If there is cold-fluid retention above the diaphragm causing dry retching, emesis should not be induced; urgent warming is required, suitable for Sini Tang (Four Reversal Decoction)."
The *Shanghan Lun* states: "In Shanghan, if hiccups occur with abdominal fullness, examine the anterior and posterior orifices to determine which is obstructed; unblocking the obstruction will cure the condition." Various methods for treating hiccups are detailed in the chapter on Hiccups (E Ni).