Ingredient Processed / Derived product (加工品 jiā gōng pǐn)

Zao Xin Tu

Hearth Center Earth · 灶心土

N/A (not derived from a living organism; this is baked earth from a traditional wood-burning stove hearth) · Terra Flava Usta

Also known as: Fu Long Gan (伏龙肝)

Zao Xin Tu (Hearth Center Earth) plant

Images shown are for educational purposes only

Zao Xin Tu is baked earth taken from the centre of a traditional wood-burning stove that has been in use for many years. It is one of TCM's unique mineral-like substances, valued for its gentle warming quality. It is primarily used to help stop bleeding, settle nausea, and ease chronic diarrhea when these problems stem from a cold, weak digestive system.

Category Hemostatic herbs (止血药)
Therapeutic focus Digestive Health Bleeding Disorders Nausea and Vomiting Relief

TCM Properties

Temperature

Warm

Taste

Acrid / Pungent (辛 xīn)

Channels entered

Spleen, Stomach

Parts used

Processed / Derived product (加工品 jiā gōng pǐn)

Educational content • Consult qualified TCM practitioners for diagnosis and treatment

What This Ingredient Does

Every ingredient has a specific set of actions — here's what Zao Xin Tu does in the body, explained in both everyday and TCM terms

Therapeutic focus

In practical terms, Zao Xin Tu is primarily used to support these areas of health:

Digestive Health Bleeding Disorders Nausea and Vomiting Relief

TCM Actions

In TCM terminology, these are the specific therapeutic actions that Zao Xin Tu performs to restore balance in the body:

Warms the Middle Burner and stops bleeding Warms the Middle Burner and Stops Vomiting Stops Diarrhea Warms the Middle Burner

How these actions work

'Warms the Middle Burner and stops bleeding' is Zào Xīn Tǔ's primary action. In TCM, the Spleen is responsible for keeping Blood flowing within the vessels. When Spleen Yang becomes deficient, it loses this governing capacity and Blood leaks out, causing bleeding that is characteristically dark in colour. Zào Xīn Tǔ, being warm and entering the Spleen and Stomach channels, directly replenishes warmth in the Middle Burner, restoring the Spleen's ability to contain Blood. It is a key substance for bleeding due to internal cold: blood in the stool, vomiting blood, nosebleeds, and uterine bleeding where the root cause is Spleen Yang deficiency.

'Warms the Stomach and stops vomiting' describes how this substance settles a cold, weak Stomach that cannot keep food down. Its warm nature and heavy, earthy quality help the Stomach direct Qi downward (its natural direction), counteracting the upward rebellion that causes nausea and vomiting. It is particularly suited to vomiting from Spleen-Stomach deficiency cold, morning sickness, and the classical condition called 'rebellious Stomach.'

'Stops diarrhea' refers to its ability to address chronic, watery diarrhea caused by Spleen Yang deficiency. When the Spleen is too cold and weak to properly transform and transport fluids, undigested food and water pass through. Zào Xīn Tǔ warms the Spleen and has a mildly consolidating quality that helps firm up the bowels.

Patterns Addressed

In TCM, symptoms cluster into recognizable patterns of disharmony. Zao Xin Tu is used to help correct these specific patterns.

Why Zao Xin Tu addresses this pattern

Spleen Yang Deficiency is the central pattern addressed by Zào Xīn Tǔ. When Spleen Yang is insufficient, the Spleen loses its ability to govern Blood, transform food and fluids, and maintain warmth in the Middle Burner. Zào Xīn Tǔ is acrid and warm, entering the Spleen and Stomach channels where it directly replenishes Middle Burner warmth. This restores the Spleen's governing function over Blood while also strengthening the Spleen's capacity to hold and transform, addressing both bleeding and diarrhea.

A practitioner would look for one or more of these signs

Dark Blood In Stool

Dark-coloured blood, appearing after the stool

Cold Limbs

Cold hands and feet from Yang deficiency

Chronic Diarrhea

Watery, unformed stools from Spleen weakness

Dull Pale Complexion

Sallow, yellowish face colour

Commonly Used For

These are conditions where Zao Xin Tu is frequently used — but only when they arise from the specific patterns it addresses, not in all cases

Arises from: Spleen Yang Deficiency Spleen not controlling Blood

TCM Interpretation

In TCM, blood in the stool can have several causes, but when the blood is dark in colour, appears after the stool, and occurs alongside signs of cold and fatigue (cold limbs, pale face, weak pulse), it points to the Spleen's failure to govern Blood. The Spleen's Yang gives it the force to keep Blood flowing within its proper pathways. When Spleen Yang declines, Blood leaks downward out of the vessels. This is fundamentally different from bloody stool caused by Heat (which produces bright red blood), and requires warming rather than cooling treatment.

Why Zao Xin Tu Helps

Zào Xīn Tǔ addresses this condition at its root by warming the Spleen Yang. As earth baked by years of fire, it embodies both warmth and the earth element, which directly support the Spleen. Its warm, acrid nature enters the Spleen and Stomach to restore the warmth needed for the Spleen to govern Blood, while its consolidating quality helps stop the bleeding. In Huáng Tǔ Tāng, it serves as the King herb at a high dose (30g), working with Fù Zǐ and Bái Zhú to warm the Spleen, balanced by Shēng Dì Huáng, Ē Jiāo, and Huáng Qín to nourish Blood and prevent the warm herbs from over-drying.

Also commonly used for

Vomiting Blood

From deficiency cold

Bleeding

Functional uterine bleeding from Yang deficiency

Nosebleeds

Chronic nosebleeds from Spleen not governing Blood

Chronic Diarrhea

Spleen Yang deficiency diarrhea

Nausea

From Spleen-Stomach deficiency cold

Peptic Ulcer

With chronic GI bleeding from cold deficiency

Chronic Gastritis

With bleeding tendency from cold deficiency

Ingredient Properties

Every ingredient has an inherent temperature, taste, and affinity for specific channels — these properties determine how it interacts with the body

Temperature

Warm

Taste

Acrid / Pungent (辛 xīn)

Channels Entered

Spleen Stomach

Parts Used

Processed / Derived product (加工品 jiā gōng pǐn)

Dosage & Preparation

These are general dosage guidelines for Zao Xin Tu — always follow your practitioner's recommendation, as dosages vary based on the formula and your individual condition

Standard dosage

15-30g

Maximum dosage

60-120g when used as a decoction base (煎汤代水, where a large quantity is decocted first, the liquid clarified, and then used as the water base for cooking other herbs). Direct decoction doses should not exceed 30g.

Dosage notes

There are two main methods of use, each with different dosage ranges. For direct decoction as part of a formula: 15-30g, wrapped in cloth (布包) and decocted first (先煎) before other herbs are added. For the 'decoction-as-water' method (煎汤代水): 60-120g is decocted in water, the liquid is allowed to settle and the clear supernatant is decanted off, then this clarified liquid is used as the base water for decocting the remaining herbs in the formula. This second method is the traditional approach in Huang Tu Tang and produces a cleaner final decoction. For powder preparations, typical doses are 6-9g taken with rice water or warm water.

Preparation

Must be wrapped in cloth (布包) before decocting to prevent the fine earth particles from making the decoction gritty and undrinkable. Should be decocted first (先煎) for 20-30 minutes before other herbs are added. Alternatively, for the traditional 'decoction-as-water' method (煎汤代水), decoct 60-120g in water, allow the sediment to settle completely, pour off the clear liquid, and use this as the base water for decocting the remaining formula herbs.

Common Ingredient Pairs

These ingredients are traditionally combined with Zao Xin Tu for enhanced therapeutic effect

Lai Fu Zi
Lai Fu Zi Zào Xīn Tǔ 30g : Fù Zǐ 9g (as in Huáng Tǔ Tāng)

Together they powerfully warm the Spleen Yang and restore its ability to govern Blood. Fù Zǐ provides strong Yang-warming force, while Zào Xīn Tǔ adds targeted Middle Burner warming with hemostatic properties. The combination addresses both the root (Yang deficiency) and branch (bleeding) simultaneously.

When to use: Spleen Yang deficiency bleeding: chronic bloody stool, vomiting blood, or uterine bleeding with dark blood, cold limbs, pale tongue, and weak pulse.

Bai Zhu
Bai Zhu Zào Xīn Tǔ 30g : Bái Zhú 9g

Bái Zhú strengthens Spleen Qi and dries Dampness, while Zào Xīn Tǔ warms the Middle Burner and consolidates the intestines. Together they address both weakness and cold of the Spleen, making them effective for chronic diarrhea and loose stools from Spleen Yang deficiency.

When to use: Spleen-deficiency diarrhea and chronic loose stools with fatigue, poor appetite, and abdominal bloating.

E Jiao
E Jiao Zào Xīn Tǔ 30g : Ē Jiāo 9g

Ē Jiāo nourishes Blood and stops bleeding through its rich, nourishing quality, while Zào Xīn Tǔ warms the Spleen Yang to restore its Blood-governing function. The pair treats both the cause of bleeding (cold deficiency) and the consequence (Blood loss), balancing warming with nourishing so neither approach overshoots.

When to use: Deficiency-cold bleeding with concurrent Blood deficiency: dark bloody stool, chronic uterine bleeding, or vomiting blood with pallor, dizziness, and fatigue.

Gan Jiang
Gan Jiang Zào Xīn Tǔ 30–60g : Gān Jiāng 6–9g

Both warm the Middle Burner but from different angles. Gān Jiāng is powerfully dispersing, driving cold out of the Spleen and Stomach, while Zào Xīn Tǔ is more settling and consolidating, anchoring warmth and stopping bleeding. Together they create both a dispersing and stabilising warming effect.

When to use: Severe Spleen-Stomach cold with both vomiting and diarrhea, or deficiency-cold bleeding that needs stronger warming than Zào Xīn Tǔ alone.

Key Formulas

These well-known formulas feature Zao Xin Tu in a prominent role

Huang Tu Tang 黄土汤 King

Huáng Tǔ Tāng (Yellow Earth Decoction) from the Jīn Guì Yào Lüè is the definitive formula for Zào Xīn Tǔ, named directly after it. It uses Zào Xīn Tǔ at a large dose (30g) as King to warm the Spleen Yang and stop bleeding, perfectly showcasing the herb's core mechanism of warming the Middle Burner to restore the Spleen's blood-governing function in chronic bloody stool, vomiting blood, and uterine bleeding from Yang deficiency.

Comparable Ingredients

These ingredients have overlapping uses — here's how to tell them apart

Gan Jiang
Zao Xin Tu vs Gan Jiang

Both warm the Middle Burner and stop bleeding from Yang deficiency. Pào Jiāng has a stronger warming and cold-dispersing action and is better for abdominal pain from cold. Zào Xīn Tǔ has a particular strength in settling the Stomach to stop vomiting, and its earthy heaviness makes it especially effective for calming a rebellious Stomach that rejects all food and medicine.

Chi Shi Zhi
Zao Xin Tu vs Chi Shi Zhi

Both are mineral/earthy substances that warm the Middle Burner and stop bleeding and diarrhea. Chì Shí Zhī is more astringent and enters the Large Intestine, giving it stronger bowel-consolidating action for severe diarrhea. Zào Xīn Tǔ has a broader range including effective anti-emetic action and stopping bleeding from any location. When Zào Xīn Tǔ is unavailable, Chì Shí Zhī is sometimes used as a substitute.

Ai Ye
Zao Xin Tu vs Ai Ye

Both warm channels and stop bleeding from cold deficiency. Ài Yè enters the Liver, Spleen, and Kidney channels and is particularly strong for warming the uterus and stopping uterine bleeding and menstrual pain. Zào Xīn Tǔ focuses on the Spleen and Stomach, excelling at stopping vomiting, settling the Stomach, and treating gastrointestinal bleeding where Ài Yè is less effective.

Common Substitutes & Adulterants

Related species and common adulterations to be aware of when sourcing Zao Xin Tu

Because Zao Xin Tu requires a traditional wood-burning clay stove that has been fired for many years, authentic material is increasingly scarce as such stoves have largely disappeared from modern life. The most important distinction is between earth from wood/grass-burning stoves (acceptable) and earth from coal-burning stoves (unacceptable and potentially toxic due to coal combustion residues). When Zao Xin Tu is unavailable, Chi Shi Zhi (赤石脂, Halloysitum Rubrum / Red Halloysite) is sometimes used as a substitute. Both are warm, astringent earth-based substances that can stop bleeding and diarrhea, though Chi Shi Zhi lacks the specific stomach-settling and anti-vomiting properties of Zao Xin Tu. Ordinary soil or kiln earth should not be confused with authentic Zao Xin Tu, which requires years of continuous fire exposure to develop its medicinal properties.

Educational content — always consult a qualified healthcare provider or TCM practitioner before using any ingredient.

Toxicity Classification

Classical Chinese pharmacopoeia toxicity rating for Zao Xin Tu

Non-toxic

Zao Xin Tu is classified as non-toxic in the classical literature. The Ben Cao Gang Mu records its properties as 'acrid, slightly warm, non-toxic' (辛，微温，无毒). The Ri Hua Zi Ben Cao described it as 'slightly toxic' and 'hot', but this minority view was not adopted by the mainstream tradition. The substance is composed of common earth minerals (silicic acid, aluminium oxide, iron oxide, calcium oxide, etc.) and poses no inherent chemical toxicity. The primary safety concern is sourcing: only earth from stoves that burned wood or dried grass is acceptable. Earth from coal-burning stoves must never be used medicinally, as it may contain harmful combustion residues, heavy metals, or toxic compounds.

Contraindications

Situations where Zao Xin Tu should not be used or requires extra caution

Avoid

Yin deficiency with Empty Heat causing bleeding. Zao Xin Tu is warm in nature and designed for cold-deficiency patterns. Using it in Yin-deficient bleeding (where Heat is driving the blood out of the vessels) would worsen the condition by adding warmth to an already overheated system.

Avoid

Vomiting or nausea caused by Heat patterns (e.g. Stomach Heat or Liver Fire). The warming nature of Zao Xin Tu would aggravate Heat-type vomiting. It should only be used for vomiting due to Spleen-Stomach cold deficiency.

Avoid

Diarrhea due to Damp-Heat or Heat toxins. As a warming and astringent substance, Zao Xin Tu would trap pathogenic Heat inside, potentially worsening the condition.

Avoid

Bleeding from excess Heat or Blood Heat patterns (e.g. bright red, forceful bleeding with signs of Heat such as red tongue, yellow coating, rapid pulse). This substance is only appropriate for pale, slow bleeding associated with Spleen Yang deficiency.

Caution

Patients without dampness or cold. As noted in the classical text Ben Cao Cong Xin (《本草从新》): without dampness, do not use.

Special Populations

Important considerations for pregnancy, breastfeeding, and pediatric use

Pregnancy

Classical sources actually list Zao Xin Tu as a substance that can 'protect the fetus' (护胎) and treat morning sickness (妊娠恶阻). It has been traditionally used for pregnancy-related nausea and vomiting when caused by Spleen-Stomach cold deficiency. However, it should not be used during pregnancy if there are any signs of Heat or Yin deficiency. As with any medicinal substance during pregnancy, use should be guided by a qualified practitioner.

Breastfeeding

No specific classical or modern contraindications exist for breastfeeding. Zao Xin Tu is a mineral-earth substance composed of common inorganic compounds (silicates, metal oxides) that are unlikely to transfer into breast milk in meaningful quantities. However, as with any warming medicinal, it should only be used when clearly indicated (cold-deficiency pattern) and not taken long-term without practitioner guidance.

Children

Zao Xin Tu has a long history of pediatric use. Classical sources record its application for childhood conditions including night crying (小儿夜啼), navel sores (脐疮), and childhood skin eruptions (丹毒). For internal use in children, dosage should be reduced proportionally based on age and body weight, typically one-third to one-half of the adult dose. The substance should always be wrapped in cloth (布包) for decoction to prevent grit in the liquid. For very young children, it may be more practical to use the decoction-as-water method (煎汤代水), decocting a larger amount (60-120g) first, then using the clarified liquid as the base for other medicines.

Drug Interactions

If you are taking pharmaceutical medications, be aware of these potential interactions with Zao Xin Tu

No well-documented pharmacological drug interactions have been established for Zao Xin Tu. The substance is composed of common inorganic minerals (silicic acid, aluminium oxide, iron oxide, calcium and magnesium oxides), which are largely insoluble and poorly absorbed. However, there are two theoretical considerations:

  • Antacid-like effects: The mineral composition may have mild acid-neutralizing properties. Patients taking medications whose absorption depends on stomach acidity (e.g. certain antifungals like ketoconazole, or iron supplements) should separate dosing times.
  • Adsorption potential: As an earth-based substance with high surface area (honeycomb-like pores), Zao Xin Tu may physically adsorb other drugs in the gastrointestinal tract, potentially reducing their bioavailability. Pharmaceutical medications should be taken at least 2 hours apart from Zao Xin Tu preparations.

Dietary Advice

Foods and dietary considerations when taking Zao Xin Tu

When taking Zao Xin Tu for cold-deficiency bleeding or diarrhea, avoid cold and raw foods, iced drinks, and excessively greasy or rich foods, as these can damage Spleen Yang and counteract the warming effect of the herb. Bland, easily digestible foods like rice porridge (白粥) are traditionally recommended alongside treatment, as noted in classical sources. If being used for nausea and vomiting, take in small sips rather than large quantities at once.

Botanical Description

Physical characteristics and morphology of the Zao Xin Tu source source material

Zao Xin Tu (灶心土) is not a plant-derived herb. It is a mineral and earth-based substance: specifically, the baked yellowish-red earth taken from the center bottom of a traditional wood- or straw-burning clay cooking stove (灶, zào) that has been fired for many years. Over prolonged exposure to heat, the clay at the stove's center undergoes slow transformation, becoming hardened, porous, and infused with fire's warmth.

The substance appears as irregular blocks of reddish-brown or orange-yellow earth, relatively hard but easily crumbled, with a fine, soft cross-section showing characteristic honeycomb-like pores. It has a faint smoky smell and a bland taste. The material is chemically composed primarily of silicic acid, aluminium oxide, and iron oxide, with smaller amounts of sodium oxide, potassium oxide, magnesium oxide, calcium oxide, and calcium phosphate.

Only earth from stoves that burned wood or dried grass is acceptable for medicinal use. Earth from coal-burning stoves must not be used. The stove should ideally have been in use for at least ten years to develop the proper qualities.

Sourcing & Harvesting

Where Zao Xin Tu is sourced, when it's harvested or collected, and how to assess quality

Harvesting season

Can be collected year-round, whenever a traditional wood- or grass-burning clay stove is being dismantled or renovated. The stove should ideally have been in use for at least ten years.

Primary growing regions

Zao Xin Tu is not cultivated or grown. It is produced wherever traditional wood- or straw-burning clay stoves have been in use for many years. Historically, it was widely available across all rural areas of China. As traditional clay stoves have largely been replaced by modern cooking methods, authentic Zao Xin Tu has become increasingly scarce. There is no specific 'terroir' region (道地药材), as quality depends on the stove's age, fuel type, and construction rather than geographic origin. The best quality comes from stoves that have burned wood or dried grass (not coal) for at least ten years.

Quality indicators

Good quality Zao Xin Tu should come from a stove that has burned wood or dried grass (never coal) for at least ten years. The blocks should be large and well-formed, with a uniform reddish-brown or orange-yellow colour. The surface typically shows knife-scraping marks from removal. The texture should be relatively hard but easily crumbled by hand, with powder falling away on handling. The cross-section should appear fine and soft with a slightly deeper colour, showing characteristic honeycomb-like small pores throughout. It should have a distinct but mild smoky aroma and a bland taste. Avoid pieces that are overly black or charred (indicating surface material that should have been trimmed away), excessively hard and stone-like, or that lack the characteristic porous internal structure.

Classical Texts

Key passages from the classical Chinese medical texts that describe Zao Xin Tu and its therapeutic uses

《名医别录》(Ming Yi Bie Lu / Supplementary Records of Famous Physicians)

Original: 伏龙肝，味辛，微温。主治妇人崩中，吐下血，止咳逆，消痈肿毒气。

Translation: Fu Long Gan (Stove-Heart Earth) is acrid in flavour and slightly warm. It treats uterine flooding in women, vomiting and downward bleeding, stops cough with counterflow, and disperses swelling of abscesses and toxic Qi.

《本草经集注》(Ben Cao Jing Ji Zhu / Tao Hongjing's Collected Commentaries)

Original: 此灶中对釜月下黄土也。以灶有神，故号为伏龙肝，并以迂隐其名尔。

Translation: This is the yellow earth from inside the stove, directly beneath the cauldron. Because the stove has a presiding spirit, it was given the name 'Fu Long Gan' (Hidden Dragon's Liver), using an indirect and concealed name.

《本草便读》(Ben Cao Bian Du)

Original: 伏龙肝即灶心土，须对釜脐下经火久炼而成形者，具土之质，得火之性，化柔为刚，味兼辛苦。其功专入脾胃，有扶阳退阴散结除邪之意。凡诸血病，由脾胃阳虚而不能统摄者，皆可用之，《金匮》黄土汤即此意。

Translation: Fu Long Gan is stove-heart earth. It must be taken from directly beneath the cauldron where prolonged fire has transformed it. It has the substance of earth and has acquired the nature of fire, transforming softness into firmness, with both acrid and bitter flavours. Its action focuses on the Spleen and Stomach, with the intention of supporting Yang, withdrawing Yin, dispersing accumulations, and expelling pathogenic factors. For all bleeding disorders caused by Spleen-Stomach Yang deficiency failing to contain the Blood, this substance may be used. The Huang Tu Tang (Yellow Earth Decoction) in the Jin Gui Yao Lue embodies this idea.

《本草汇言》(Ben Cao Hui Yan)

Original: 伏龙肝，温脾渗湿，性燥而平，气温而和，味甘而敛，以藏为用者也。故善主血失所藏。

Translation: Fu Long Gan warms the Spleen and drains dampness. Its nature is dry yet balanced, its Qi warm yet harmonious, its flavour sweet yet astringent, functioning through the principle of storage. Therefore it excels at treating Blood that has lost its proper containment.

Historical Context

The history and evolution of Zao Xin Tu's use in Chinese medicine over the centuries

Origin and Etymology of the Name

Zao Xin Tu (灶心土, "stove-heart earth") is the common name for this substance, but its more literary classical name is Fu Long Gan (伏龙肝, "Hidden Dragon's Liver"). This poetic name derives from the association between the cooking stove and its presiding deity. The "Hidden Dragon" (伏龙, Fú Lóng) is actually the name of the stove god (灶神, Zào Shén), one of the five household spirits in Chinese folk religion. The character "liver" (肝, gān) was used as a literary substitute for "earth" or "soil" (土, tǔ). As Tao Hongjing explained in his commentary, the elegant name was deliberately chosen to conceal the humble origin of the substance.

Famous Clinical Use

A well-known story links this substance to the Song Dynasty pediatric physician Qian Yi (钱乙). According to tradition, the crown prince of Emperor Shenzong suffered from intractable diarrhea that resisted all treatment. Qian Yi prescribed Huang Tu Tang (Yellow Earth Decoction), whose key ingredient was Zao Xin Tu. The emperor was initially incredulous that mere stove earth could serve as medicine, but after Qian Yi's thorough explanation, the prescription was prepared. The prince reportedly recovered after just two doses. This anecdote helped cement both Qian Yi's reputation and the status of Zao Xin Tu in clinical practice.

Classical Significance

The substance was first recorded in the Ming Yi Bie Lu (《名医别录》, circa 2nd-3rd century CE), classified as a "lower grade" drug. Its most famous formula application is in Huang Tu Tang (黄土汤) from Zhang Zhongjing's Jin Gui Yao Lue (《金匮要略》, circa 3rd century CE), where it serves as the chief herb for treating chronic bleeding due to Spleen Yang deficiency. Li Shizhen in the Ben Cao Gang Mu (《本草纲目》, 1590) placed it in the Earth section (土部) and greatly expanded its recorded indications. With the disappearance of traditional clay stoves in modern China, this once-common household medicinal has become increasingly rare, sometimes replaced by similar earth-based substances like Chi Shi Zhi (赤石脂, Halloysitum Rubrum).