麻黄（三两，去节） 桂枝（二两，去皮） 甘草（一两，炙） 杏仁
（七十个，去皮尖） 上四味，以水九升，先煮麻黄，减二升，此须多煮，取其力专，不仅为去上沫，止煮一、
二沸矣。去上沫，纳诸药，煮取二升半，去渣，温服八合，覆取微似汗，不须啜粥，以其易发汗也。余如桂枝
将息法。《活人书》云∶夏至后用麻黄汤，量加知母、石膏、黄芩，盖麻黄性热，恐有发黄斑出之虑。
太阳病，头痛发热，身疼腰痛，骨节疼痛，此痛处，比桂枝症尤多而重，因荣卫俱伤故也。恶风无汗而喘
者，此二症乃肺气不舒之故。麻黄治无汗；杏仁治喘；桂枝甘草，治太阳诸症，无一味不紧切，所以谓
之经方。麻黄汤主之。
太阳与阳明合病，阳明之病象甚多，如身热不恶寒，口苦鼻干之类，但见一、二症即是，不必全具也。
太阳病即上文所指者。喘而胸满者，不可下，病俱在上焦。宜麻黄汤主之。喘而胸满，此麻黄症之太阳
合阳明也。
太阳病，十日以去，过经。脉浮细，邪已退。而嗜卧者，正渐复。外已解也，设胸满胁痛者，与小柴胡
汤；胸满胁痛，病延日久，邪留少阳，故与此汤。脉但浮者，与麻黄汤。若果邪在少阳，脉必带弦，今但浮，则
尚在太阳矣，故仍用麻黄汤，此亦从脉不从症之法。
太阳病，脉浮紧，无汗，发热身疼痛，此乃太阳伤寒的症。经云∶诸紧为寒。八、九日不解，表证仍
在，表证即上文数端。此当发其汗，宜麻黄汤。服药已微除，其人发烦目瞑，阳郁而不能外达。剧者必衄，
衄乃解。热甚动血，血由肺之清道而出，与汗从皮毛而泄同，故热邪亦解。俗语所云“红汗”也。经云∶阳
明病口燥，但欲漱水不欲咽者，此必衄。所以然者，阳气重故也。风郁固为热，寒郁亦为热。《内经》云∶热
病者，皆伤寒之类也。麻黄汤主之。此言未衄之前，可用麻黄。非衄后更用麻黄也。
脉浮者，病在表，可发汗，宜麻黄汤。此脉浮必带紧。
脉浮而数者，可发汗，宜麻黄汤。数为阳气欲出。
伤寒脉浮紧，不发汗，失治。因致衄者，麻黄汤主之。前段衄后而解，则不必复用麻黄，衄后尚未解，
则仍用此汤。
阳明病，脉浮无汗而喘者。阳明本脉大自汗，今乃脉浮无汗而喘，则为麻黄汤症矣。发汗则愈，宜麻黄汤。
麻黄（三两，去掉节部） 桂枝（二两，去掉皮） 甘草（一两，蜜炙） 杏仁（七十个，去掉皮和尖）以上四味药，用九升水，先煮麻黄，水量减少二升，这一步需要多煮，是为了取其药力专一，不仅仅是为了去除上面的浮沫，只煮开一、两沸就可以了。去掉上面的浮沫，放入其他药物，煮取二升半药液，去掉药渣，温服八合，服药后覆盖衣被使身体微微出汗，不需要喝热粥，因为本方容易发汗。其余调养方法参照桂枝汤的将息法。《活人书》说：夏至之后使用麻黄汤，要酌情加入知母、石膏、黄芩，大概是因为麻黄性热，担心会导致发黄或出现斑疹的顾虑。
太阳病（太阳经受邪所致的病证），头痛发热，身体疼痛腰痛，骨节疼痛，这些疼痛的部位，比桂枝汤证更多且更重，这是因为营卫之气都受到损伤的缘故。怕风无汗并且气喘，这两个症状是肺气不舒展的原因。麻黄治疗无汗；杏仁治疗气喘；桂枝和甘草治疗太阳病的各种症状，没有一味药不是紧扣病机的，所以称之为经方。用麻黄汤主治。
太阳病与阳明病同时发病，阳明病的病象很多，如身热不怕冷、口苦鼻干之类，只要见到一两个症状就可以确诊，不必全部具备。这里的太阳病即上文所指的症状。气喘并且胸部胀满的，不可用攻下法，因为病邪都在上焦。适宜用麻黄汤主治。气喘并且胸部胀满，这是麻黄汤证中太阳病合并阳明病的情况。
太阳病，过了十天，已经过了病程阶段。脉象浮而细，说明邪气已退。如果病人想睡觉，说明正气逐渐恢复，体表之邪已解。假如出现胸满胁痛，给予小柴胡汤；胸满胁痛，是因为病情拖延日久，邪气留在少阳经，所以给予此汤。如果脉象只是浮，给予麻黄汤。如果果真是邪在少阳，脉象必然带弦，现在脉只是浮，则邪气尚在太阳经，所以仍然用麻黄汤，这也是“从脉不从症”的方法。
太阳病，脉象浮紧，无汗，发热身体疼痛，这是太阳伤寒的确切证候。医经说：各种紧脉主寒。经过八、九天病仍未解除，表证仍然存在，表证即上文提到的几种情况。此时应当发汗，适宜用麻黄汤。服药后症状轻微缓解，病人感到心烦、眼睛昏花，这是阳气郁结不能外达所致。严重的必定会流鼻血，流鼻血后病就会解除。热势盛导致动血，血液从肺的清道而出，与汗从皮毛泄出相同，所以热邪也随之解除。俗语所说的“红汗”。医经说：阳明病口干，只想含水漱口而不想咽下，这必定会发生鼻衄。之所以这样，是因为阳气重的缘故。风邪郁结固然生热，寒邪郁结也会生热。《内经》说：热病，都属于伤寒一类。用麻黄汤主治。这里说的是还没有流鼻血之前，可以用麻黄汤。并不是流鼻血之后再用麻黄汤。
脉象浮的，病在表，可以发汗，适宜用麻黄汤。这种脉浮必然带有紧象。
伤寒脉象浮紧，没有及时发汗，属于失治。因此导致流鼻血的，用麻黄汤主治。前一段讲的是流鼻血后病解，就不必再用麻黄汤；流鼻血后病尚未解除，则仍然用此汤。
阳明病，脉象浮、无汗并且气喘的。阳明病本来的脉象是大脉且自汗，现在是脉浮无汗而喘，这就成了麻黄汤的证候了。发汗就会痊愈，适宜用麻黄汤。
Ephedrae Herba (Mahuang, 麻黄) (three liang, remove nodes), Cinnamomi Ramulus (Guizhi, 桂枝) (two liang, remove bark), Glycyrrhizae Radix et Rhizoma (Gancao, 甘草) (one liang, honey-fried), Armeniacae Semen Amarum (Xingren, 杏仁) (seventy seeds, remove skin and tips). The above four ingredients are boiled in nine sheng of water. First, boil Ephedrae Herba until the volume reduces by two sheng; this requires prolonged boiling to extract its potent efficacy, not merely to skim off the foam on the surface, which would only require one or two boils. After skimming off the foam, add the remaining herbs and boil to obtain two and a half sheng of decoction. Strain the dregs and take eight he of the warm decoction. Cover with blankets to induce a slight sweat. There is no need to drink hot porridge, as this formula induces sweating easily. Rest other care instructions follow those for Guizhi Tang (Cinnamon Twig Decoction). The *Huoren Shu* (Book of Vitality) states: When using Mahuang Tang after the Summer Solstice, Zhi Mu (Anemarrhenae Rhizoma), Shigao (Gypsum Fibrosum), and Huangqin (Scutellariae Radix) should be added in measured amounts, likely because Mahuang is hot-natured, raising concerns about potential jaundice or eruption of macules.
Taiyang disease (disease of the Taiyang channel), characterized by headache, fever, body ache, lower back pain, and joint pain. These painful areas are more numerous and severe than in Guizhi Tang syndrome, due to the injury of both Ying (Nutritive) and Wei (Defensive) qi. Aversion to wind, absence of sweating, and wheezing are caused by the stagnation of Lung Qi. Mahuang treats absence of sweating; Xingren treats wheezing; Guizhi and Gancao treat various symptoms of Taiyang disease. Every ingredient is precisely targeted, hence it is called a Jingfang (Classic Prescription). Mahuang Tang is indicated.
Combined Taiyang and Yangming disease involves many manifestations of Yangming disease, such as fever without aversion to cold, bitter taste in the mouth, and dry nose. The presence of one or two symptoms is sufficient for diagnosis, not all need to be present. The Taiyang disease here refers to the symptoms mentioned above. Wheezing with chest fullness indicates that purgation is contraindicated, as the pathogen resides in the Upper Jiao (Upper Burner). Mahuang Tang is appropriate. Wheezing with chest fullness represents the combination of Taiyang and Yangming diseases within the context of Mahuang Tang syndrome.
If Taiyang disease persists for ten days, passing the typical stage, and the pulse is floating and fine, the pathogen has receded. If the patient desires to sleep, it indicates the gradual recovery of Zhengqi (Upright Qi), and the exterior has resolved. However, if there is chest fullness and hypochondriac pain, Xiaochaihu Tang (Minor Bupleurum Decoction) should be administered; this occurs when the disease lingers for a long time and the pathogen remains in the Shaoyang (Lesser Yang) channel. If the pulse is merely floating, administer Mahuang Tang. If the pathogen were truly in Shaoyang, the pulse would necessarily be wiry (xian); since it is only floating, the pathogen remains in Taiyang, thus Mahuang Tang is still used. This exemplifies the principle of "following the pulse rather than the symptoms."
Taiyang disease with a floating-tight pulse, absence of sweating, fever, and body pain constitutes the definitive pattern of Taiyang Cold Damage (Shanghan). The Classics state: "All tight pulses indicate Cold." If unresolved after eight or nine days, and the exterior syndrome persists (referring to the aforementioned symptoms), diaphoresis (sweating therapy) is indicated, and Mahuang Tang should be used. After taking the medicine, symptoms may slightly alleviate, but the patient may experience irritability and blurred vision, indicating that Yang Qi is constrained and unable to reach the exterior. In severe cases, epistaxis (nosebleed) will occur, leading to resolution. Excessive heat agitates the blood, causing it to exit through the clear passages of the Lung, similar to sweat exiting through the skin pores; thus, the heat pathogen is also resolved. This is colloquially known as "red sweat." The Classics state: "In Yangming disease, if the mouth is dry and the patient only wishes to rinse their mouth without swallowing, epistaxis is certain." This is because the Yang Qi is heavy. Wind constraint generates heat, and Cold constraint also generates heat. The *Neijing* (Inner Canon) states: "Heat diseases all belong to the category of Cold Damage." Mahuang Tang is indicated. This passage refers to the use of Mahuang before epistaxis occurs, not after.
A floating pulse indicates an exterior disease, suitable for diaphoresis; Mahuang Tang is appropriate. This floating pulse must be accompanied by a tight quality.
A floating and rapid pulse indicates suitability for diaphoresis; Mahuang Tang is appropriate. A rapid pulse signifies that Yang Qi is attempting to emerge.
In Cold Damage, a floating-tight pulse without timely diaphoresis constitutes mismanagement. If this leads to epistaxis, Mahuang Tang is indicated. In the previous section, epistaxis led to resolution, so Mahuang was not reused; if epistaxis occurs but the disease remains unresolved, this formula is still employed.
Yangming disease presenting with a floating pulse, absence of sweating, and wheezing. Yangming disease typically presents with a large pulse and spontaneous sweating. Here, the floating pulse, absence of sweating, and wheezing constitute a Mahuang Tang syndrome. Diaphoresis will lead to recovery; Mahuang Tang is indicated.