What Er Chen Tang is for
This is the simplest and most used Phlegm formula, and on the skin it works on tissue that has gone soft and heavy: puffy, doughy areas that pit slightly and hold the shape of a finger, under a pale and often oily surface. Nothing in the picture is red, and nothing in it is dry, so the work is to dry the fluid that makes the tissue heavy and keep it from gathering again.
The skin looks waterlogged rather than inflamed: pale, slightly shiny or oily, spongy under the finger, and it keeps a dull imprint where it has been pressed. Soft swellings, small pale cysts or nodules may sit within it, and they do not throb or redden. The surface is cool and the colour is flat, which is what separates this from a hot, angry eruption, and the whole area feels heavier than it looks.
Ban Xia dries the thickened fluid and transforms the Phlegm. Chen Pi moves the Qi that allowed it to settle, so what has been dispersed does not gather again in the same place. Fu Ling drains the fluid and supports the Spleen that produced it, which addresses the source rather than the surface, and Gan Cao harmonises the group. The change in the skin is gradual: puffiness reduces, the oily sheen dulls, and the soft nodules flatten.
It is warm and drying, so it is wrong for thin, dry or flaky skin, which will only become drier. Where the picture has turned hot, with red inflamed lesions and a yellow greasy coating, cooling herbs must be added and the formula becomes a different one. Short to medium courses are the rule, because the drying action accumulates and the skin stops benefiting from more of it.
Actions
- Dries Dampness and transforms Phlegm
- Regulates Qi and harmonises the middle
- Stops nausea
- Supports the Spleen
Properties
- Taste and temperature: Predominantly acrid and slightly bitter with mild sweetness. Acrid disperses and moves stagnant Qi and Phlegm, bitter dries Dampness, sweet harmonises.
- Organs: Spleen, Stomach, Lungs
- Channels: Spleen, Stomach, Lung
The pattern behind it
The root is a Spleen that is not transforming fluids properly, so they gather as Dampness and thicken into Phlegm. The Phlegm then obstructs the middle and can settle in the skin as soft swellings. The formula drains what has formed with Fu Ling and transforms it with Ban Xia, while Chen Pi keeps the Qi moving so it does not re-form.
Composition
The herbs in Er Chen Tang, with their role and dose.
| Role | Herb | Dose | Properties | Why it is there |
|---|---|---|---|---|
| Deputy | Ban Xia | 9 to 15 g | Warm, Pungent | Dries Dampness, transforms Phlegm and lowers rebellious Stomach Qi, so it also addresses nausea. |
| Assistant | Chen Pi | 9 to 15 g | Warm, Pungent, bitter | Moves Qi and dries Dampness so the transformed Phlegm does not simply settle again. |
| Envoy | Fu Ling | 6 to 9 g | Neutral, Sweet, bland | Drains Dampness out and supports the Spleen, addressing the source of the Phlegm. |
| Gan Cao | 3 to 5 g | Neutral, Sweet | Harmonises the formula and supports the middle. |
Patterns it treats
Damp-Phlegm
Pale, oily or doughy skin that pits under the finger and holds its shape, with soft cysts or nodules that do not redden. The fluid has thickened and settled beneath the surface, which is why the tissue is heavy and spongy rather than hot or tight.
How the formula is built
Two herbs transform the Phlegm and two support the middle. Ban Xia and Chen Pi are both warm and drying, so they deal with the Phlegm directly; Fu Ling gives the Dampness a route out; Gan Cao holds the formula together. It is a small, focused prescription, and the many Phlegm formulas that follow are built by adding to it.
Skin conditions it is used for
Where this formula appears in the skin conditions of the library.
Preparation and use
Decocted in water with a little ginger, taken warm in two divided doses.
Modifications
- If Heat is present, cooling herbs are added and the formula becomes Wen Dan Tang.
- If the Spleen deficiency is marked, tonics are added as in Liu Jun Zi Tang.
- If nausea dominates, ginger and aromatic herbs are increased.
- If the swelling is nodular and hard, Phlegm-breaking herbs are added.
Timing
Taken warm in two divided doses, often with meals.
Duration
Short to medium term: one to four weeks, reassessed as symptoms change. Not intended for prolonged unmodified use because of its drying nature.
Diet while taking it
Avoid cold, raw, greasy and sweet food, which generate Dampness, and reduce dairy.
Safety
Contraindications
Avoid in dry cough from Yin deficiency or Lung dryness. The warm drying herbs, especially Ban Xia and Chen Pi, would worsen dryness. Avoid in Phlegm-Heat without adding cooling herbs, and in any bleeding tendency since the drying and moving action can aggravate it.
Interactions
Gan Cao may interact with diuretics, digoxin and corticosteroids. The drying nature may also affect fluid balance when combined with diuretics.
Pregnancy
Use with caution in pregnancy. Ban Xia is traditionally classified among pregnancy-caution herbs because of its acrid, warm and drying nature.
Breastfeeding
Use only under professional guidance.
Children
Used in children with reduced dose for damp-phlegm digestive and skin pictures.
Before you use it
Recorded from the classical record and rewritten in this project's own words. Educational only: not a prescription.
General safety references
General references for herbal hepatotoxicity and herb-drug interactions; they are not specific to this formula.
- Review article: Herbal hepatotoxicity - an update on traditional Chinese medicine preparations. Alimentary Pharmacology & Therapeutics, 2014. PMID: 24844799.
- Interactions between herbal medicines and prescribed drugs: an updated systematic review. Drugs, 2009. PMID: 19719333.
- Warfarin and food, herbal or dietary supplement interactions: a systematic review. British Journal of Clinical Pharmacology, 2021. PMID: 32478963.
Selected PubMed records
Real PubMed records for the modern, non-TCM discussion of this formula. They are references, not a claim that the formula is proven for any skin condition.
- Mechanisms of Er Chen Tang on Treating Asthma Explored by Network Pharmacology and Experimental Verification.. Combinatorial chemistry & high throughput screening, 2024. PMID: 37138477.
- Meta-analysis of the efficacy of Er Chen Tang in the adjuvant treatment of obesity: A study protocol for systematic review and meta-analysis.. Medicine, 2024. PMID: 38847686.
Origin and history
Tai Ping Hui Min He Ji Ju Fang (太平惠民和剂局方, Formulas from the Imperial Pharmacy), Song dynasty, 12th century.
Er Chen Tang comes from the Song government formulary, which standardised formulas in use at the time. Its name refers to the two herbs that are best when aged, Ban Xia and Chen Pi. Because it is small and effective for the damp-phlegm picture, it became the base from which the other Phlegm formulas were built, including the hot and the deficient versions.
Evidence note
No controlled trial of this treatment in skin conditions was identified for this entry. What is described here rests on the classical and later materia medica record and on traditional clinical use, not on controlled trial evidence, and it is not a prediction of benefit. Where skin-specific research does exist it is linked above.
Common questions
Why is it called two-cured?
The name refers to the two herbs that are considered best when aged: Ban Xia and Chen Pi. Chen Pi literally means aged peel.
Can it be used for oily skin?
Yes, for the damp-phlegm type with puffiness and a greasy tongue coat. Oily skin with red inflamed acne is heat and needs different herbs.
Is it suitable for dry skin?
No. It is warm and drying and would make dry skin worse.
How long can it be taken?
One to four weeks, reassessed as symptoms change. Prolonged use without modification is not advised because it dries the body.