Er Miao San (二妙散) — Two Marvel Powder

Er Miao San is a classical Chinese herbal formula used primarily for damp-heat eczema and dermatitis below the waist. It is prescribed for Damp-Heat in the lower Burner: red, weeping, itchy eczema below the waist; foul-smelling profuse yellow vaginal discharge; hot painful red swollen lower-limb joints; lower-limb weakness with damp heaviness; yellow greasy tongue coat and a slippery rapid pulse.

On this page

1. Overview
2. TCM pattern
3. Key herbs
4. Formula actions
5. Conditions treated
6. Cautions
7. Frequently asked questions

What is Er Miao San?

Er Miao San — Two Marvel Powder — is a classical Yuan dynasty formula from Zhu Danxi’s Dan Xi Xin Fa (1481). Simple but powerful, it is one of the most widely used base formulas in Chinese herbal medicine for Damp-Heat in the lower Burner — the underlying pattern in many cases of eczema below the waist, painful inflamed lower-limb joints and foul vaginal discharge.

I prescribe Er Miao San as part of bespoke herbal formulas from pharmaceutical-grade granules sourced from Sun Ten in Taiwan.

Er Miao San TCM pattern

Prescribed for Damp-Heat in the lower Burner: red, weeping, itchy eczema below the waist; foul-smelling profuse yellow vaginal discharge; hot painful red swollen lower-limb joints; lower-limb weakness with damp heaviness; yellow greasy tongue coat and a slippery rapid pulse.

Key herbs

1. Huang Bai (Cx. Phellodendri, 6-15g) — clears Damp-Heat from the lower Burner
2. Cang Zhu (Rz. Atractylodis, 6-15g) — strongly dries Damp and tonifies the Spleen

Formula actions

1. Clears heat and dries Damp in the lower Burner
2. Eases Damp-Heat painful obstruction in the lower limbs

Conditions treated

1. Damp-Heat eczema and dermatitis below the waist
2. Damp-Heat painful Bi syndrome of the knee, ankle and foot (often gout flares)
3. Damp-Heat vaginal discharge with foul smell
4. Damp-Heat prostatitis with perineal heaviness
5. Damp-Heat lower-back pain with thick yellow coat
6. Often combined with other herbs as a base; San Miao San adds Niu Xi, Si Miao San adds Niu Xi and Yi Yi Ren

Cautions

Contraindicated in pure cold-deficient patterns and Yin-deficient heat without Damp. Use cautiously in pregnancy.

Always consult a qualified Chinese herbalist registered with the Register of Chinese Herbal Medicine (RCHM). Online herbal consultations are available.

Prefer to be treated from home? Chinese herbal medicine online consultations are available throughout the UK and worldwide.

Frequently asked questions about Er Miao San

What is Er Miao San used for?

Er Miao San is used for damp-heat eczema and dermatitis below the waist, damp-heat painful bi syndrome of the knee, ankle and foot (often gout flares), damp-heat vaginal discharge with foul smell, damp-heat prostatitis with perineal heaviness, damp-heat lower-back pain with thick yellow coat. The formula targets the underlying TCM pattern producing these symptoms rather than the symptom in isolation, which is why pattern diagnosis by a qualified herbalist is essential.

How does Er Miao San work?

The herbs in Er Miao San work together: Huang Bai (Cx. Phellodendri, 6 15g) — clears damp-heat from the lower burner; Cang Zhu (Rz. Atractylodis, 6 15g) — strongly dries damp and tonifies the spleen. The synergy of these actions addresses the underlying TCM pattern.

How long does Er Miao San take to work?

For most patients, an improvement is typically noticed within 2–4 weeks of daily granule treatment. Full benefit usually requires 6–12 weeks, depending on how long-standing the underlying pattern is. Er Miao San is typically prescribed as part of an individualised treatment plan that may include other herbs or adjustments over time.

Is Er Miao San safe in pregnancy?

Use cautiously in pregnancy. As with any Chinese herbal formula, prescription in pregnancy should only be by a qualified RCHM herbalist with pregnancy training.

Who should not take Er Miao San?

Contraindicated in pure cold-deficient patterns and Yin-deficient heat without Damp. Use cautiously in pregnancy. Always consult a qualified Chinese herbalist registered with the Register of Chinese Herbal Medicine (RCHM). Online herbal consultations are available. Prefer to be treated from home? Chinese herbal medicine online consultations are available throughout the UK and worldwide. Er Miao San must be prescribed only after full pattern diagnosis by a qualified RCHM herbalist; self-prescription is not appropriate.