A foundational "dry dampness, transform phlegm, regulate qi, harmonize the center" formula from the Song dynasty, the ancestor of nearly every later phlegm-damp formula in the tradition.
Cultural reference - how this formula has been discussed in Chinese medical tradition. Not medical advice.
Background & origin
Finalized in the Song dynasty "Formulary of the Bureau of Medicine" (《太平惠民和剂局方》) as the foundational "phlegm-damp" formula. In Japan, Nichin-to (二陳湯) is sold by Tsumura and Kracie as the standard OTC for "phlegm, chest fullness, morning nausea". In Korea it appears as Ijin-hwan (이진환) in the Kyungdong hanbang line. The formula's name "Er Chen" literally means "two aged [herbs]", referring to the long-aged tangerine peel and well-cured pinellia that the original recipe specified.
From the source text
This page is cultural documentation, not medical advice.
From the source text · 卷四·治痰饮·二陈汤
Classical text
治痰饮为患，或呕吐恶心，或头眩心悸，或中脘不快，或发为寒热，或因食生冷，脾胃不和，并宜服之。
Modern Chinese rendering
本方用于痰饮为患所致的呕吐恶心、头眩心悸、中脘不快、寒热往来，或因过食生冷、脾胃不和等证。这一段方论把二陈汤定位为"治痰饮通治方"——后世把"二陈"作为化痰方剂的代名词,实自《局方》始,也是"燥湿化痰、理气和中"思路下"治痰之基础方"路径的经典条目。
Editorial translation
This formula is used for patterns of phlegm-rheum causing disease: vomiting and nausea, dizzy head and palpitations, discomfort in the middle burner, alternating fever and chills, or disharmony of the spleen and stomach from eating raw and cold foods. This preface positions Èr Chén Tāng as the Formulary's "all-purpose phlegm-rheum formula" — the later tradition's use of "Èr Chén" as a metonym for phlegm-resolving formulas in general traces back to this entry — and the canonical foundation formula for the "dry dampness and transform phlegm, regulate qi and harmonize the middle" (燥湿化痰，理气和中) approach.
In tradition
In TCM tradition, associated with "phlegm-damp" patterns: chronic cough with thin white phlegm, chest and epigastric fullness, nausea, a sensation of heaviness, dizziness, and a generally "phlegmy" feel to the body and mind. It is the formula of choice when phlegm is the primary complaint rather than qi deficiency, and is the parent formula for dozens of later phlegm-damp variations.
Formula composition
Monarch1
- Pinellia rhizome, processed (Bàn Xià / 半夏)
Minister1
- Tangerine peel, aged (Chén Pí / 陈皮)
Assistant3
- Poria (Fú Líng / 茯苓)
- Ginger (Shēng Jiāng / 生姜)
- Chinese date (Dà Zǎo / 大枣)
Envoy1
- Licorice root, honey-fried (Zhì Gān Cǎo / 炙甘草)
International availability
Japan (Kampo)
- Tsumura & Co.ツムラOTC二陳湯Nichin-to
Korea (Hanbang)
- Kyungdong경동OTC이진탕Ijin-tang
Taiwan & Hong Kong
- 順天堂OTC二陳丸Er Chen Wan
Cautions & context
- Contains pinellia, which is generally considered inappropriate during pregnancy unless under qualified guidance.
- Not appropriate for what TCM describes as "yin deficiency with dry cough", the formula is drying and may worsen dryness.
- Long-term daily use may over-dry the body in some constitutions, periodic breaks are typically recommended.
- Persistent cough, coughing blood, or unexplained weight loss requires medical evaluation before any herbal remedy is considered.
Related formulas
Other formulas from this text· "Formulary of the Bureau of Medicine"
Other formulas by this contributor· Imperial Medical Bureau (Song)
Related concerns
Concern · digestion
Digestion
Upper-abdominal heaviness, bloating, sour reflux, loose stools, traveler's stomach, and the aftermath of a meal that was richer, spicier, or larger than usual.
Editorial note
Compiled from "Formulary of the Bureau of Medicine" (1078).
Last reviewed: July 18, 2026
Three layers of evidence
Classical source
≈ 900 years · "Formulary of the Bureau of Medicine" (1078)
Pharmacopoeia indication
"Dry dampness and resolve phlegm, regulate qi and harmonize the stomach. Used for phlegm-damp stagnation: cough with profuse phlegm, chest and epigastric fullness, and nausea with vomiting."
Modern research status
As of 2026-07-18, a PubMed search using the formula name and the Latin / Korean / Japanese transliterations together with "systematic review" and "meta-analysis" did not identify a dedicated systematic review for this formula. Any clinical evidence that does exist is fragmented across small individual trials or covered in broad herbal-medicine umbrella reviews, which do not allow a per-formula evidence assessment; the absence of a dedicated SR is itself the relevant editorial fact here.
References
References reviewed on July 18, 2026 · PubMed search on 2026-07-18
- 01ClassicalChen Shiwen (陈师文) et al. (eds.), 《太平惠民和剂局方》 (Tài Píng Huì Mín Hé Jì Jú Fāng / Formulary of the Bureau of Medicine), Song dynasty, compiled 1078, vol. 4, the "treating phlegm-rheum" (治痰饮) section, the entry for Èr Chén Tāng (二陈汤), the canonical Song-era "all-purpose phlegm-rheum formula", the foundation formula for the "dry dampness and transform phlegm, regulate qi and harmonize the middle" (燥湿化痰，理气中和) approach.
- 02TextbookDuan Fuqin (段富津) et al. (eds.), 《方剂学》 (Fāngjìxué / Science of Formulas), 2nd edition, Shanghai Scientific and Technical Publishers, 2011, the standard modern university-level formula textbook in mainland China, with Èr Chén Tāng analysed as the foundation formula for the "dry dampness and transform phlegm, regulate qi and harmonize the middle" (燥湿化痰，理气和中) approach, the parent formula for dozens of later phlegm-damp variations including Wēn Dǎn Tāng and Dǎo Tán Tāng.
- 03TextbookTsumura & Co. (ツムラ), Nichin-to (二陳湯) product documentation, Japan's leading Kampo manufacturer, the standard Japanese OTC adaptation of the Èr Chén Tāng lineage, used for "phlegm, chest fullness, morning nausea" presentations in Japanese Kampo clinical practice, listed in the Japanese Kampo formulary as the standard phlegm-damp formula.
- 04PharmacopoeiaPharmacopoeia Commission of the PRC, 《中华人民共和国药典》 2020 edition, vol. 1 (Zhōnghuá Rénmín Gònghéguó Yàodiǎn, Pharmacopoeia of the People's Republic of China, 2020 ed., vol. 1), China Medical Science Press, 2020, the official national monograph for Èr Chén Wán (and Èr Chén Tāng dosage form), "functional indication" reads "dry dampness and transform phlegm, regulate qi and harmonize the stomach, used for phlegm-damp stagnation causing cough with profuse phlegm, chest and epigastric fullness, nausea with vomiting".