禀天地清阳刚烈之气，故味苦气温。气味俱薄，轻清而浮，阳也，升也，无毒。手
太阴之药，入足太阳经，兼走手少阴阳明经。轻可去实，故疗伤寒，为解肌第一。
麻黄，中风伤寒，头痛温疟，皮肉不仁，发汗解表，冬月正伤寒如神，春初真温
疫并妙，泄卫热黑斑赤疹，去营寒头痛身热。春末温疟勿加，夏秋寒疫切禁，仍破积
聚坚，更劫咳逆痿痹，痰哮气喘，并凄神功。凡寒邪深入，非麻黄不能逐，但在佐使
之妙。兼气药助力，可得卫中之汗；兼血药助液，可得营中之汗∶兼温药助阳，可逐阴
凝寒毒；兼寒药助阴；可解炎热瘟邪。但患者多服，必致亡阳，盖气味轻清，升浮发表
太过耳。根节止汗，效同影响，因有善行肌表之性，能引诸药直固腠理也。麻黄，其形
中空，散寒邪而发表，其节中闭，止盗汗而固虚。
主治（痘疹合参） 泄卫实，去营寒，调血脉，通九窍，开毛孔，发汗解肌，消赤
黑斑毒。痘疮倒靥黑陷者，用麻黄去根节半两，先用沸汤泡过，晒干细切，又以酒浸良
久，瓦器炒令焦黑色，乃用水煎，乘热尽服。服后不得见风，其疮复出。若以酒煎，
功效尤速。出迟者亦可用。至有冬月感冒大寒，而痘难出，发热恶寒者，用之以散寒
邪。一见点忌服。更有一种痘极硬，而不肯灌浆者，名为铁甲痘，用此令痘作烂，方有
生机。然开窍走泄太甚，误用则表虚气脱。
按∶麻黄轻可去实，为发散第一药。惟当冬月，在表真有寒邪者宜之。如无寒邪，
或寒邪在里，乃伤寒有汗等病，虽发热恶寒皆不可用。即可汗之症，亦不宜多服，盖汗
为心液，误汗过汗，则心血为之动矣。或至亡阳，或至衄血，可不慎与？故麻黄治卫实
之药，桂枝治卫虚之药也。
麻黄禀受天地之间清阳、刚烈之气，因此味道苦，性质温。其气味都较淡薄，质地轻清而向上浮升，属于阳性药物，具有上升发散的特性，没有毒性。它是入入手太阴肺经的药物，同时进入足太阳膀胱经，并兼走手少阴心经和手阳明大肠经。因其药性轻扬，能祛除体内的实邪，所以是治疗伤寒病的要药，被誉为解肌发表的第一良药。
麻黄可用于治疗中风、伤寒引起的头痛、温疟（一种以寒热往来为特征的疟疾），以及皮肤肌肉麻木不仁等症状；它能发汗解表，在冬季治疗典型的伤寒病效果如神，在初春治疗真正的瘟疫也极为巧妙；它能宣泄卫分的热毒，治疗因热毒导致的黑斑、赤疹，去除营分的寒邪，缓解头痛身热。但在春末时节，温疟患者不宜加入麻黄；夏秋季节的寒疫患者则严禁使用。此外，麻黄还能攻破积聚坚结，更擅长劫除咳逆、痿痹，对于痰哮、气喘等症也有神奇的功效。凡是寒邪深入体内，非用麻黄不能驱逐，关键在于配伍佐使药的巧妙运用。如果配合气分药助力，可获取卫分之汗；配合血分药助液，可获取营分之汗；配合温热药助阳，可驱逐阴凝寒毒；配合寒凉药助阴，可解除炎热瘟邪。但是，如果患者服用过多，必然导致亡阳（阳气暴脱），这是因为其气味轻清，升浮发表的作用太过强烈所致。麻黄的根节具有止汗功效，效果显著，因为它善于行走于肌表，能引导其他药物直接巩固腠理（皮肤纹理及毛孔）。麻黄整体形态中空，能散寒邪而发表；其节部中间闭合，能止盗汗而固护虚损。
主治（结合痘疹病症参考）：宣泄卫分实邪，去除营分寒邪，调理血脉，通利九窍，开启毛孔，发汗解肌，消除赤色或黑色的斑毒。对于痘疮倒靥（痘疹内陷）、颜色黑陷的情况，取麻黄去根节半两，先用沸水浸泡，晒干后细细切碎，再用酒浸泡良久，放入瓦器中炒至焦黑色，然后用水煎煮，趁热全部服下。服药后不得见风，否则痘疮会重新发出。如果用酒煎煮，功效更加迅速。对于出痘迟缓者也可以使用。至于冬季感受大寒，导致痘疹难以透出，出现发热恶寒症状的，可用麻黄来散寒邪。但一旦见到痘点发出，就禁忌服用。还有一种情况是痘疹极其坚硬，不肯灌浆的，称为“铁甲痘”，用此药令痘疹溃烂化脓，才有生机。然而，麻黄开窍走泄之力太强，误用会导致表虚气脱。
按语：麻黄药性轻扬，能祛除实邪，是发散类药物的第一选择。只有在冬季，体表确实存在寒邪时才适宜使用。如果没有寒邪，或者寒邪在体内，或者是伤寒已有汗出的病症，即使有发热恶寒的症状也不可使用。即使是适合发汗的病症，也不宜多服，因为汗为心之液，误汗或过汗会导致心血动荡。甚至可能导致亡阳或鼻出血，能不谨慎吗？所以说，麻黄是治疗卫分实证的药物，桂枝是治疗卫分虚证的药物。
Mahuang (Ephedrae Herba) inherits the clear, yang, and vigorous qi of heaven and earth; therefore, its taste is bitter and its nature is warm. Its flavor and aroma are both thin, making it light, clear, and floating upward; it belongs to Yang and possesses ascending and dispersing properties. It is non-toxic. It enters the Hand-Taiyin Lung Meridian, the Foot-Taiyang Bladder Meridian, and also traverses the Hand-Shaoyin Heart Meridian and Hand-Yangming Large Intestine Meridian. Because it is light, it can dispel excess, thus treating Shanghan (Cold Damage) and serving as the premier herb for releasing the muscle layer.
Mahuang treats wind-strike, Shanghan, headache, Wen Nue (Warm Malaria), and numbness of the skin and flesh; it induces sweating to release the exterior. In winter, it is miraculous for typical Shanghan; in early spring, it is excellent for true epidemics. It vents heat from the Wei (Defensive) level, treating black spots and red rashes caused by heat toxicity, and removes cold from the Ying (Nutritive) level to relieve headache and fever. However, it should not be added for Wen Nue in late spring, and it is strictly prohibited for cold epidemics in summer and autumn. Furthermore, it breaks up accumulations and hardness, and is particularly effective in subduing cough with counterflow, flaccidity, and bi-syndrome, as well as phlegm-wheezing and asthma. For deep-penetrating cold pathogens, only Mahuang can drive them out, provided that the skillful use of assistant and guiding herbs is applied. Combined with Qi-moving herbs to assist power, it yields sweat from the Wei level; combined with Blood-nourishing herbs to assist fluids, it yields sweat from the Ying level; combined with warming herbs to assist Yang, it drives out Yin-congealed cold toxins; combined with cooling herbs to assist Yin, it resolves hot epidemic pathogens. However, excessive consumption by patients will inevitably lead to Wang Yang (collapse of Yang), due to its light and clear nature causing excessive ascending, floating, and exterior-releasing effects. The root nodes (Genjie) stop sweating with significant efficacy because they possess a nature that travels well on the body surface, capable of guiding other herbs to directly consolidate the Cou Li (pores and interstitial spaces). Mahuang’s shape is hollow in the center, dispersing cold pathogens and releasing the exterior; its nodes are closed inside, stopping night sweats and securing deficiency.
Main Indications (Integrated with Smallpox/Rash Diseases): Vents Wei excess, removes Ying cold, regulates blood vessels, unblocks the nine orifices, opens pores, induces sweating and releases the muscle layer, and eliminates red/black spot toxins. For smallpox/rash lesions that have inverted, retracted, or turned black and sunken, take half liang of Mahuang with roots and nodes removed. First soak in boiling water, dry, cut finely, then soak in wine for a long time. Stir-fry in a clay vessel until charred black, then decoct with water and drink all while hot. After ingestion, avoid exposure to wind, lest the lesions reappear. Decocting with wine yields even faster results. It may also be used for delayed eruption. In cases of severe cold contraction in winter preventing rash eruption, accompanied by fever and aversion to cold, Mahuang is used to disperse cold pathogens. However, once the rash points appear, it is contraindicated. Another condition involves extremely hard rashes that refuse to fill with pus, known as "Iron Armor Rash"; this herb causes the rash to ulcerate, creating a chance for survival. Nevertheless, its opening and draining action is too strong; misuse leads to exterior deficiency and Qi collapse.
Commentary: Mahuang is light and dispels excess, ranking first among dispersing herbs. It is suitable only in winter when there is genuine cold pathogen on the exterior. If there is no cold pathogen, or if the cold pathogen is interior, or in conditions like Shanghan with sweating, even if fever and aversion to cold are present, it must not be used. Even in syndromes suitable for sweating, it should not be taken in excess, because sweat is the fluid of the Heart; mistaken or excessive sweating agitates Heart Blood. This may lead to collapse of Yang or epistaxis (nosebleed); how can one not be cautious? Therefore, Mahuang is the herb for treating Wei excess, while Guizhi Tang (Cinnamon Twig Decoction) is the herb/formula for treating Wei deficiency.