气味辛、平，有毒。主伤寒寒热，心下坚，胸胀咳逆，头眩，咽喉肿痛，肠鸣，下气
，止汗。
陈修园曰∶半夏气平，禀天秋金之燥气，而入手太阴；味辛有毒，得地西方酷烈之味，
而入
手足阳明。辛则能开诸结，平则能降诸逆也。伤寒寒热、心下坚者，邪积于半表半里之间，
其主之者，以其辛而能开也。胸胀咳逆、咽喉肿痛、头眩上气者，邪逆于巅顶胸膈之上，其
主之者，以其平而能降也。鸣者，大肠受湿，则肠中切痛而鸣濯濯也；其主之者，以其辛平
能燥湿也。又云止汗者，别着其辛中带涩之功也。仲景于小柴胡汤用之治寒热，泻心汤用之
以治胸满肠鸣，少阴咽痛亦用之，《金匮》头眩亦用之，且呕者必加此味，大得其开结降逆
之旨。用药悉遵《本经》，所以为医中之圣。
又曰∶今人以半夏功专祛痰，概用白矾煮之，服者往往致吐，且致酸心少食，制法相沿
之陋
也。古人只用汤洗七次，去涎，今人畏其麻口，不敢从之。余每年收干半夏数十斤，洗去粗
皮，以生姜汁、甘草水浸一日夜，洗净，又用河水浸三日，一日一换，滤起蒸熟，晒干切片
，隔一年用之，甚效。此药盖是太阴、阳明、少阳之大药，祛痰却非专长。故仲景诸方加减
，俱云呕者加半夏，痰多者加茯苓，末闻以痰多加半夏也。
气味辛、平，有毒。主治伤寒引起的寒热往来，心下痞硬，胸胁胀满咳嗽气逆，头晕目眩，咽喉肿痛，肠鸣，以及降气、止汗。
陈修园说：半夏气平，禀受秋天金气的燥性，因此入足太阴肺经；味辛且有毒，得自西方酷烈之味，因此入手阳明大肠经和手少阳三焦经。辛味能开通各种郁结，平性能降泄各种上逆之气。伤寒寒热、心下痞硬，是邪气积聚在半表半里之间，用半夏治疗，是因为它辛散能开结。胸胁胀满、咳嗽气逆、咽喉肿痛、头晕及气机上逆，是邪气逆乱于头顶胸膈之上，用半夏治疗，是因为它性平能降逆。肠鸣，是大肠受湿邪侵袭，导致肠中剧烈疼痛并发出濯濯声响；用半夏治疗，是因为它辛平之性能燥湿。又说它能止汗，这是特别指出它辛中带涩的功效。张仲景在小柴胡汤中使用它来治疗寒热往来，在泻心汤中使用它来治疗胸满肠鸣，治疗少阴咽痛也使用它，《金匮要略》中治疗头晕也使用它，并且凡是有呕吐症状的必定加入此药，这完全符合它开通郁结、降泄逆气的宗旨。用药完全遵循《神农本草经》，所以被称为医中之圣。
又说：现在的人认为半夏的功效专门在于祛痰，一概用白矾煮制，服用者往往引起呕吐，并且导致胃部泛酸、食欲不振，这是制法沿袭下来的弊端。古人只用热水清洗七次，去除涎沫，现在的人害怕它刺激口腔发麻，不敢照做。我每年收购干半夏几十斤，洗去粗皮，用生姜汁、甘草水浸泡一天一夜，洗净，再用河水浸泡三天，每天换一次水，滤出蒸熟，晒干切片，隔一年后再使用，效果很好。这种药可以说是太阴、阳明、少阳经的大药，祛痰并非它的专长。所以张仲景的各个方剂加减法中，都说呕吐加半夏，痰多加茯苓，从未听说痰多加半夏的。
Taste: Acrid, Neutral; Toxic.
Indications: Mainly treats chills and fever in Shanghan (Cold Damage), hardness beneath the heart, chest distension with cough and rebellious Qi, dizziness, sore throat and swelling, intestinal borborygmus, descending Qi, and stopping sweating.
Chen Xiuyuan stated: Banxia (Pinelliae Rhizoma) has a neutral nature, inheriting the dryness of the Autumn Metal Qi, thus entering the Hand-Taiyin Lung Meridian; its taste is acrid and toxic, deriving from the harsh flavor of the West, thus entering the Hand-Yangming Large Intestine Meridian and Hand-Shaoyang Sanjiao Meridian. The acridity can open various accumulations, while neutrality can descend various rebellious Qi. Chills and fever in Shanghan, and hardness beneath the heart, indicate pathogenic factors accumulating between the exterior and interior; it is used because its acridity can resolve accumulation. Chest distension, cough with rebellious Qi, sore throat and swelling, dizziness, and upward rushing Qi indicate pathogenic factors rebelling above the vertex and chest/diaphragm; it is used because its neutrality can descend rebellion. Borborygmus occurs when the Large Intestine is affected by dampness, causing severe pain and gurgling sounds in the intestines; it is used because its acrid and neutral nature can dry dampness. It is also said to stop sweating, highlighting its function of being slightly astringent within its acridity. Zhang Zhongjing uses it in Xiaochaihu Tang (Minor Bupleurum Decoction) to treat chills and fever, in Xiexin Tang (Drain the Epigastrium Decoction) to treat chest fullness and intestinal borborygmus, in Shaoyin sore throat formulas, and in Jinkui Yaolue (Essential Prescriptions from the Golden Cabinet) for dizziness. Furthermore, it is invariably added when there is vomiting, fully grasping the principle of resolving accumulation and descending rebellion. Adhering strictly to the Benjing (Divine Farmer's Materia Medica) in medication usage is why he is revered as the Sage of Medicine.
He further stated: Modern practitioners believe Banxia's primary function is specifically to resolve phlegm, generally boiling it with Mingfan (Alumen). Patients often experience vomiting, acid reflux, and loss of appetite due to this processing method, which is a陋 (vulgar/defective) practice inherited over time. Ancients only washed it seven times with water to remove saliva/phlegm. Modern people fear its numbing effect on the mouth and dare not follow this. I purchase dozens of jin of dried Banxia annually, wash off the coarse skin, soak it in fresh ginger juice and licorice water for one day and night, rinse clean, then soak in river water for three days, changing the water daily. After filtering, steaming until cooked, drying, and slicing, it is used after one year, yielding excellent results. This herb is a major medicine for the Taiyin, Yangming, and Shaoyang meridians; resolving phlegm is not its exclusive specialty. Therefore, in Zhang Zhongjing's formula modifications, it is stated that "add Banxia for vomiting" and "add Fuling (Poria) for excessive phlegm"; it is unheard of to add Banxia for excessive phlegm.