Zoological substancesWind-damp dispellingBombycis Faeces

Can Sha (Silkworm Excrement)

A practical guide to Can Sha: what it is, how Traditional Chinese Medicine uses it, the classical formulas it appears in, and who should be careful with it.

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Last reviewed Oct 29, 2026

Quick Facts

Latin Name	Bombycis Faeces
Chinese Name & Pinyin	蠶沙 · Can Sha
Medicinal Part	Zoological substances
The item	Can Sha is the dried feces of the domestic silkworm. It is used raw and is wrapped in a cloth bag for decocting.
Nature and channels	Sweet, acrid, neutral. Enters the Spleen, Stomach, and Liver. It is mild — disperses without being harsh and harmonizes the middle.
Pharmacopoeia line	Dispels wind-dampness and harmonizes the stomach. Used for wind-damp bi pain, heavy sore limbs, poor appetite, abdominal fullness, vomiting and diarrhea, and summer-dampness heaviness.
Pattern cues	Stiff sore joints in damp weather. Heavy limbs. Poor appetite and bloating in muggy heat.
In this article	Can Sha versus Du Huo. Mild stomach-harmonizing dampness-dispersing versus warm channel-scattering. Why it is wrapped in cloth. Why a dry yin-deficient stomach is a poor match. Why pregnancy is a caution. Who should skip it.

What Is Can Sha?

Can Sha (蚕沙; Cán Shā; Latin: Faeces Bombycis; English: silkworm droppings) in the current pharmacopoeia is the dried feces of the domestic silkworm, collected after cocooning and used raw. It is sweet and acrid and neutral, enters the Spleen, Stomach, and Liver channels, and its core actions are to dispel wind-dampness, and to harmonize the stomach and transform dampness. It is light and floats, so it is wrapped in a cloth bag for the decoction. The usual amount is 5–15 g. It is mild enough for a gentle tea, but not meant for long daily drinking. A warm-soaked bath can also be used externally for itchy rash.

It is not Du Huo. Angelica Pubescentis is acrid, bitter, and warm. It warms and frees the channels to drive out deep cold-wind from the joints, but it does not harmonize the stomach at all. Spleen-stomach yin deficiency, with a dry mouth and dry stools, is a poor match. Red, swollen, hot, painful joints of damp-heat bi should not be self-treated. Use caution in pregnancy. Sudden summer vomiting and diarrhea that keeps worsening needs a clinic first.

It is used most often for three patterns:

Wind-damp bi pain: stiff sore joints, heavy limbs, worse in damp weather
Dampness obstructing the stomach: poor appetite, bloating, nausea in muggy heat
Summer-dampness vomiting and diarrhea with abdominal pain — seek care

Sweet, acrid, and neutral, it is not a daily “dampness tea” to keep brewing. Using it when there is no dampness, in a yin-deficient dry stomach, dries the fluids and adds to the discomfort.

When wind-dampness lodges in the muscles and joints, or dampness clogs the spleen and stomach, heavy limbs, stiff joints, and poor appetite are common. Can Sha is sweet, acrid, and neutral. It dispels wind-dampness and harmonizes the stomach, which is why it appears in Can Shi Tang (Silkworm Droppings Decoction)–type formulas. It harmonizes more than it attacks. A yin-deficient stomach, with a dry mouth and dry stools, gets worse if more is added.

Can Sha is not a catch-all dampness or joint powder. In spleen-stomach yin deficiency, in red swollen hot joints, or in pregnancy without guidance, using it alone is a poor match. Raw granules or a paired formula, and whether it belongs in a prescription, should be decided by a licensed Chinese medicine practitioner after pattern diagnosis.

Can Sha: Materia Medica Profile

Identification & Quality Standard

Bombycis Faeces

Botanical Origin

The dried feces of the larva of Bombyx mori Linnaeus (Bombycidae).

Production Regions

Produced in silkworm-rearing regions of China; main production in Jiangsu, Zhejiang, Sichuan, Guangdong.

Quality Requirements

Superior material is dry, dark brown, even and free of mildew.

Macroscopic Features

Short oval or cylindrical granules, 2~5 mm long, 1.5~3 mm diameter; externally dark brown or brownish-black, rough, with 6 subtle longitudinal ridges; light, brittle; fractured granular; faint odor; slightly sweet and pungent taste.

Main Regions and Quality Identification

Traditional materia medica and industry experience value the Jiang-Zhe region — such as Zhejiang, Jiangsu, and Sichuan — because the local sericulture is developed, the silkworm-raising scale is large, and the raw-material supply is stable. But actual quality also depends on variety, harvest time, processing, and storage. In appearance, good-quality Can Sha is granular, 2–5 mm long and 1–2 mm in diameter, gray-black or black-brown on the surface, rough, with 6 obvious longitudinal ridges, somewhat hard in texture, not easy to crush between fingers, with a faint mulberry-leaf fragrance and no musty or sour off-odors. The common look-alikes are the feces of other insects, such as cockroach droppings — irregular in form, without Can Sha's longitudinal ridges, and usually with a different odor — to be distinguished carefully.

Traditional Properties & Historical Lineage

Nature, Flavour & Channel Tropism

Sweet, Acrid; WarmLiverSpleenStomach

1. Records in Classic Materia Medica

Shen Nong Ben Cao Jing: lists Can Sha as middle grade — mainly used for intestinal rumbling, wasting-thirst, and wind-damp bi pain.
Ming Yi Bie Lu: adds that it mainly treats intestinal rumbling, heat wasting-thirst, wind bi, and urticaria.
Xin Xiu Ben Cao: mentions that Can Sha can be made into a bath decoction to remove wind-itching and urticaria.
Ben Cao Gang Mu: further states it can treat wasting-thirst, masses, women's blood collapse, head wind, wind-red eyes — dispelling wind and removing dampness.
De Pei Ben Cao: stresses that it can harmonize the spleen and stomach, dispel wind-dampness, and transform turbidity to descend rebellion.

These records all revolve around Can Sha's wind-damp-dispelling and stomach-harmonizing actions, without mentioning overly broad other effects.

2. How Views of Its Nature Changed

Views among physicians differ somewhat. The early Shen Nong Ben Cao Jing stressed its treatment of wind-damp bi pain and the spleen-stomach-related intestinal rumbling and wasting-thirst — leaning to dispel the evil while regulating the spleen and stomach; Ben Cao Gang Mu added applications for gynecological bleeding and head-wind eye diseases on the original basis, extending its scope; some later physicians stressed Can Sha's balanced nature, holding that it fits people with spleen-stomach weakness complicated by dampness evil, and should not be used for the extremes of pure excess or pure deficiency. This difference reflects Can Sha's character as a balanced herb — it does not fit every constitution and must be adjusted according to the specific pattern.

Core Efficacies & Traditional Applications

Traditional Functions

Dispels wind-dampness, harmonizes stomach and transforms dampness.

1. First Direction: Dispelling Wind and Removing Dampness

Traditional action: dispel the dampness evil and wind evil lodged in the muscles and joints — one of Can Sha's core traditional actions.
Typical signs: wind-damp bi pain with stiff, limited joints and sore limbs, and the heavy limbs and skin numbness of dampness invasion — such patterns mostly appear in the plum-rain season or in people long in damp environments.
Usual combinations: clinically often paired with wind-damp-dispelling herbs such as Du Huo and Wei Ling Xian to strengthen the evil-dispelling force; if cold signs accompany, Gui Zhi and other channel-warming herbs can be added.
Who should not self-use: those with a heat-prone constitution and the dampness-heat bi pattern of red, swollen, hot, painful joints; pregnant women should be cautious — consult a physician before considering use.

2. Second Direction: Harmonizing the Stomach and Resolving Dampness

Traditional action: act on the spleen and stomach — resolve the internal dampness evil and harmonize the spleen-stomach function.
Typical signs: dampness obstructing the spleen and stomach — poor appetite, abdominal distension, vomiting and diarrhea; and the heavy head and body, chest tightness, and nausea of the summer-dampness season — mostly related to food accumulation or external summer-dampness invasion.
Usual combinations: pair with dampness-transforming, stomach-harmonizing herbs such as Huo Xiang and Pei Lan to strengthen the stomach-harmonizing effect; if food stagnation accompanies, add Shan Zha and Mai Ya to guide digestion.
Who should not self-use: those with spleen-stomach yin deficiency — dry mouth and tongue, dry, bound stool; children and the elderly should mind the dose, to avoid damaging the spleen-stomach healthy qi.

3. Classic Pairing: Can Sha With Yi Yi Ren

Can Sha with Yi Yi Ren is a common pairing. Can Sha's actions are dispelling wind-dampness and harmonizing the stomach to resolve dampness; Yi Yi Ren's actions are draining water and dampness, strengthening the spleen, and stopping diarrhea. The two coordinate — removing the dampness evil of the muscles and joints while resolving the damp stagnation of the spleen and stomach — fitting the patterns of dampness evil with spleen-stomach weakness, commonly shown as heavy limbs, poor appetite, and loose stool. To be stressed: this pairing needs the physician's pattern diagnosis before use — do not pair casually on your own.

Modern Research

Modern research offers useful context, but Traditional Chinese Medicine prescribes on whole-pattern diagnosis rather than isolated compounds.

1. Main Chemical Constituents

The constituents detected in Can Sha mainly include flavonoids, coumarins, organic acids, amino acids, vitamins, and minerals. The roles should be clearly distinguished: the flavonoid constituents detected in the material showed a certain antioxidant activity in in vitro experiments; in animal experiments, a high dose of the Can Sha extract showed a slight inhibiting effect on joint inflammation. There is not yet sufficient human clinical research confirming the specific action of the Can Sha extract on humans.

2. Current Research Directions

Current research on Can Sha mainly focuses on the separation and identification of its active constituents, and preliminary exploration of its inflammation-response and antioxidant actions:

In in vitro cell experiments, some extracts can reduce the release of inflammatory factors.
Research currently concentrates on screening the active constituents and exploring their potential in regulating metabolism.

Such results cannot be directly equated with Can Sha's efficacy on humans — more human research is needed to verify its actual effect.

3. Limitations of Current Research

Lab results are not clinical efficacy — in vitro and animal results are obtained under controlled conditions, differing greatly from the complex human physiological environment — they cannot be directly inferred as therapeutic effects on humans.
Extracts and monomers are not the same as traditional decoction pieces — modern studies mostly use the extract or single constituents, while daily use is the whole slice; the material basis and dose form differ completely and cannot be converted directly.
Doses and preparation methods vary between studies — some studies use high-concentration extracts while the daily slice dose is lower, and differences in the extraction process affect the constituent composition, making the results hard to unify.
A single component does not define the whole herb — Can Sha's action is the result of many constituents working together; a single constituent's activity cannot represent the whole herb's overall action.

Comparing Similar Herbs

1. What They Share

Choosing Du Huo as the similar herb, the two share these points:

Both have the wind-damp-dispelling action, and both can be used for the limb soreness and joint stiffness of wind-damp bi pain.
Both need constitution and dose considered — those with a heat-prone constitution should use cautiously, to avoid worsening the heat.
In daily regulation, both can serve as auxiliary herbs in food therapy or teas for wind-damp discomfort.

2. The Key Differences: Can Sha vs. Du Huo

Nature and flavors: Can Sha is balanced with sweet and pungent flavors — gentle, neither cold nor hot; Du Huo is warm with pungent and bitter flavors — leaning warm, able to warm and free the channels.
Focus: besides dispelling wind-dampness, Can Sha also harmonizes the stomach and resolves dampness, attending to the spleen-stomach — fitting people with dampness plus spleen-stomach discomfort; Du Huo's action centers on dispelling wind-dampness — good at removing the deep wind evil of the joints, with more prominent improvement of joint cold pain, and basically not involving the spleen-stomach.
Qi tendency: Can Sha's action leans harmony — scattering the dampness of the muscle surface while regulating the spleen-stomach qi — a "harmonize-the-middle" action; Du Huo's action leans warm-scattering — warming and freeing the channels and driving out the deep cold-wind evil — a "scatter-the-evil" action, regulating the qi of the channels and joints without involving the spleen-stomach.
Best fit: Can Sha fits the cases of dampness with spleen-stomach discomfort — heavy limbs, poor appetite, and loose stool together; Du Huo fits pure wind-damp bi pain, especially joint cold pain worsening in cold, without obvious spleen-stomach discomfort.
Not suitable: Can Sha is not for those with spleen-stomach yin deficiency and dry mouth; Du Huo is not for those with a heat-prone constitution and red, swollen, hot, painful joints; both need attention — pregnant women should be cautious with either.
Use scenes: Can Sha more often appears in daily food therapy — boiled as tea or added to tonic food — for mild damp spleen-stomach and joint discomfort; Du Huo more often appears in physician-prescribed formulas — for the more obvious wind-damp bi pain, especially joint cold pain.

3. One-Sentence Summary

Simply put, Can Sha leans toward balanced dampness-dispelling that also attends to the spleen and stomach, whereas Du Huo leans toward warming and freeing the channels to scatter cold and wind. Both can be used for wind-damp bi pain, but they are not interchangeable.

Classical Formulas Containing Can Sha

Classic Formula 1: Can Shi Tang (Silkworm Droppings Decoction)

Combination logic: Can Shi Tang is a classic formula from the Huo Luan Lun. Can Sha is the lord — mainly dispelling wind-dampness and harmonizing the stomach to transform turbidity — combined with Yi Yi Ren and Da Dou Huang Juan to resolve the dampness-heat and turbidity inside, together with Huang Lian and Huang Qin to clear dampness-heat, and Ban Xia and Chen Pi to harmonize the stomach and stop vomiting. As the lord, Can Sha attends to both dispelling wind and harmonizing the stomach — the key to solving the heavy limbs and the spleen-stomach discomfort at once. The herb alone cannot be used, because a formula needs the synergy of many herbs to attend to both clearing dampness-heat and harmonizing the spleen and stomach.

Traditional use: traditionally used for dampness-heat internal accumulation with Huo Luan vomiting and diarrhea — abdominal pain with diarrhea, vexation and thirst, and limb soreness — while also attending to the discomforts of dampness blockage.

Modern note: modern clinical use requires a doctor's pattern diagnosis and standard care — do not self-apply just because the formula name relates to "Huo Luan" (cholera); adjust the use according to your specific pattern.

Classic Formula 2: Er Miao San Jia Can Sha (Two Marvels Powder with Can Sha)

Combination logic: Er Miao San is a classic heat-clearing, dampness-removing formula from the Dan Xi Xin Fa, originally centered on Huang Bai and Cang Zhu for dampness-heat bi pain. With Can Sha added, Can Sha serves as an auxiliary — strengthening the stomach-harmonizing, dampness-resolving action while attending to dispelling wind — better improving the cases of dampness-heat with spleen-stomach discomfort.

Traditional use: traditionally used for dampness-heat bi pain with spleen-stomach disharmony — red, swollen, painful joints, poor appetite, and sticky stool.

Modern note: modern clinical use of this modified formula likewise requires a doctor's pattern diagnosis and standard care — do not self-prepare; adjust the dose and combination according to the individual constitution.

Formulas vs. Single Herbs

A formula is the result of many herbs acting together — the effects of Can Shi Tang and the modified Er Miao San come from the synergy of many herbs; single Can Sha cannot simply replicate a full formula's effect. The doses and combinations in a formula are holistic — for example, in Can Shi Tang, Can Sha's dose works together with the other herbs to perform the dispel-wind-and-harmonize-stomach action; taking Can Sha alone cannot reach the same effect. Readers often misunderstand: a herb that works in a formula means taking it alone is also effective — in fact, a single herb's action is limited and cannot replace the formula's overall effect. Do not build formulas from online articles.

Diet & Daily Home Use

1. Home Tea

Tea — Can Sha Chen Pi Cha: Can Sha 10 g, Chen Pi 5 g, a suitable amount of clean water. Wash the Can Sha and Chen Pi, put into a pot with 500 ml of clean water, decoct 15 minutes, take the liquid and drink as tea. Suited to the plum-rain or summer-dampness season with heavy head and body, poor appetite, and mild abdominal distension. Not for those with spleen-stomach yin deficiency — dry mouth and tongue, dry, bound stool — or pregnancy. Suggested: 2–3 times a week, 1 dose each time; do not drink continuously long-term.

2. Decoction and Processing Differences

The raw and processed forms of Can Sha differ little — generally the raw product is used, with no special processing needed. At home, Can Sha is light in texture and does not sink easily; it can be put into a gauze bag before adding to the pot, to avoid floating during decoction and affecting the drinking. Can Sha needs no pre-boiling, late addition, or direct swallowing — decoct normally. The basic home method: soak the herbs in clean water 30 minutes, bring to a boil over high heat, then turn to low heat and cook 15–20 minutes, take the liquid and drink.

3. Dosage and Course

The common dose in traditional prescriptions is 5–15 g; the food-therapy dose is generally 5–10 g — somewhat smaller than the medicinal dose. Long-term continuous use is not advised — generally do not use beyond 7 days each time; if the symptoms do not ease, consult a physician. Special groups — such as children and the elderly — should halve the dose and use it under a physician's or pharmacist's guidance.

Contraindications & Safety Warnings

1. Who Should Avoid It

Spleen-stomach yin deficiency — dry mouth and tongue, dry, bound stool — and the dampness-heat bi pattern of red, swollen, hot, painful joints — not for use.
Pregnancy and breastfeeding — use cautiously — consult a physician before deciding whether to use it.
Children and the elderly — weaker spleen-stomach function — strictly control the dose, to avoid damaging the healthy qi.
Liver or kidney impairment — Can Sha is metabolized through the liver and kidneys — consult a doctor before use.
Allergy to Can Sha or silkworm-related substances — not for use.

2. Interactions and Diet Notes

There is no sufficient evidence of a general "food clash" between ordinary foods, but certain herbs can interact with specific drugs — those on medication should consult a doctor or pharmacist first. Research on Can Sha's interactions with anticoagulants, blood-pressure medications, and glucose-lowering medications is still limited — if you take such drugs, tell the doctor before using Can Sha, to avoid affecting the drug effect. Can Sha may affect the absorption of some drugs — it is suggested to take it 1–2 hours apart from other medications, to reduce the possibility of interaction.

3. Adverse Reactions and Overdose Risk

Can Sha has few adverse reactions, but overdose may bring spleen-stomach discomfort such as bloating and diarrhea. If marked discomfort, allergy signs (rash, itching), persistent vomiting, breathing difficulty, altered consciousness, or rapidly worsening symptoms appear, stop at once and seek medical care.

Frequently Asked Questions About Can Sha

What is Cansha? Is it the same as Jiangcan or Dilong?

Cansha is the dried feces of the silkworm larva Bombyx mori, Latin name Bombycis Faeces. It is a common Chinese medicine centered on dispelling wind-damp and harmonizing the stomach to transform turbidity. Jiangcan extinguishes wind and stops spasms. Dilong clears heat and unblocks collaterals. They cannot be used interchangeably in equal amounts. Prescribe as Cansha. Caution when blood fails to nourish the sinews.

What are the composition and effects of Cansha?

Pharmacopoeial name Cansha, Latin Bombyx mori L. Sweet and pungent in taste, warm in nature, enters the Liver, Spleen and Stomach meridians. Functions to dispel wind-damp and harmonize the stomach to transform turbidity. Used for wind-damp bi pain, vomiting and diarrhea with cramps, and wind rash itching. Dispels wind and transforms turbidity.

How to choose between raw and processed? Can Jiangcan replace it?

Feces are used raw, wrapped for decoction. Jiangcan emphasizes extinguishing wind rather than transforming turbidity, and cannot replace it in equal amounts. Commercial products are standardized; do not adjust arbitrarily.

What is the dosage of Cansha? Can it be used daily as a wind-dispelling tea?

Decoction, 10-15g, wrapped. Modern use requires physician-determined dosage. It is not a year-round "Cansha tea." Cases where blood fails to nourish the sinews will be further injured by prolonged use. Bi pain requires short-term, physician-determined dosage and cannot replace evaluation.

What are the contraindications of Cansha? Can pregnant women use it?

Not suitable when blood fails to nourish the sinews or for hemiplegia. Pregnant women require physician evaluation. Stop if loose stools or abdominal pain occur. Seek immediate medical care for joint redness and swelling or high fever.

Can Cansha dispel wind-damp and harmonize the stomach to transform turbidity?

It can assist wind-damp bi pain, vomiting and diarrhea with cramps, and wind rash itching. It dispels wind-damp and harmonizes the stomach to transform turbidity, but is not a specific remedy for all bi pain or all itching.

Can Cansha be taken daily as a wind-dispelling or turbidity-transforming tea?

Wind-cold-damp bi can be used short-term in formulas; cases where blood fails to nourish the sinews will be further injured. The idea that "Cansha must dispel wind" cannot replace evaluation. Dispelling wind-damp and transforming turbidity requires physician-determined formulation and dosage.

How to choose between Cansha, Jiangcan, Dilong, Mugua, and Yiyiren?

Cansha dispels wind-damp and harmonizes the stomach, suited to bi pain and cramps. Jiangcan extinguishes wind and stops spasms. Dilong clears heat and unblocks collaterals. Mugua relaxes sinews and activates collaterals. Yiyiren strengthens the spleen and drains dampness. Choose Cansha for dispelling wind; Jiangcan for extinguishing wind; Dilong for unblocking collaterals; Mugua for relaxing sinews; Yiyiren for draining dampness. Pattern differentiation applies, but large doses of Cansha are contraindicated when blood fails to nourish the sinews.

How is Cansha commonly modified? What is a representative usage?

Modifications depend on the pattern. Add Fangji for bi pain; add Mugua for cramps. Specify Cansha; do not substitute Jiangcan in equal amounts for transforming turbidity.

How to select and store Cansha?

Choose regular Chinese medicinal materials with intact feces. Discard if moldy, damp, or abnormal in odor. Store in a dry place. Purchase "Cansha"; do not substitute Jiangcan or Dilong in equal amounts for dispelling wind-damp and harmonizing the stomach to transform turbidity.

Related Products

Nong's Can Sha (Silkworm Droppings) Single Herb 5:1 Concentrated Granules $53.68

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Hoi Tin Can Sha (Silkworm Feces) Single Herb 10:1 Concentrated Granules $26.30

Medical Disclaimer — This article is provided for educational purposes only and describes traditional Chinese medicine concepts. It is not medical advice, and it is not intended to diagnose, treat, cure or prevent any disease. Always consult a qualified practitioner before using any herb, particularly if you are pregnant, nursing, taking medication or managing a diagnosed condition.