LeavesDampness-drainingPyrrosiae Folium

Shi Wei (Japanese Felt Fern)

Q: What are the contraindications of Shiwei? Can pregnant women use it?

It is not suitable for yin deficiency without damp-heat. Pregnant women require physician evaluation. Stop if dry mouth or lumbar soreness occur. Seek immediate medical care for severe stones or high fever.

A practical guide to Shi Wei: 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	Pyrrosiae Folium
Chinese Name & Pinyin	石韋 · Shi Wei
Medicinal Part	Leaves
The item	Shi Wei is the dried leaf of the pyrrosia fern, used raw as cut segments. It goes straight into a normal decoction.
Nature and channels	Bitter, sweet, cold. Enters the Lung and Bladder. It drains downward and clears dampness-heat, with no tonifying action.
Pharmacopoeia line	Promotes urination and relieves strangury. Clears heat and stops bleeding. Used for heat strangury, stone strangury, painful scanty urine, and blood in the urine.
Pattern cues	Burning painful urination. Dark-yellow scanty urine. Blood in the urine. Lower abdominal fullness.
In this article	Shi Wei versus Qu Mai. Stop-bleeding versus break-blood-unblock-menses. Why pregnancy is a caution. Why a cold weak stomach is a poor match. Why blood in the urine needs a clinic. Who should skip it.

What Is Shi Wei?

Shi Wei (石韦; Shí Wéi; Latin: Pyrrosiae Folium; English: pyrrosia leaf) in the current pharmacopoeia is the dried leaf of the pyrrosia fern, used raw as cleaned cut segments. It is bitter and sweet and cold, enters the Lung and Bladder channels, and its core actions are to promote urination and relieve strangury, and to clear heat and stop bleeding. It goes straight into a normal decoction, with no special preparation. The usual amount is 6–12 g. It is not a daily urinary tea.

It is not Qu Mai. Pink herb is bitter and cold, enters the Heart and Small Intestine, and breaks blood to unblock the menses. Shi Wei is bitter-sweet and cold, enters the Lung and Bladder, and its second talent is cooling to stop bleeding rather than breaking stasis. Spleen-stomach deficiency-cold, with abdominal pain, loose stools, and cold limbs, is a poor match. Yin deficiency without damp-heat should not self-use a draining herb. Use caution in pregnancy. Blood in the urine needs a clinic first.

It is used most often for three patterns:

Heat strangury: painful burning urination, dark-yellow scanty urine
Frequent hesitant urination with lower abdominal fullness
Blood in the urine with a burning urethra — seek care

Bitter, sweet, and cold, it is not a daily “urine tea” to keep brewing. Draining when there is no damp-heat, in a cold weak stomach, damages yang and loosens the stools.

When dampness-heat clogs the bladder and scorches the waterways, painful urination, dark urine, and even blood in the urine are common. Shi Wei is bitter, sweet, and cold. It clears dampness-heat, promotes urination, and cools to stop bleeding, which is why it appears in Shi Wei San (Pyrrosia Powder)–type formulas. It drains more than it tonifies. A spleen and stomach that already run cold, with abdominal pain and loose stools, get worse if more is added.

Shi Wei is not a catch-all urinary or cooling leaf. In spleen-stomach deficiency-cold, in yin deficiency without damp-heat, or in pregnancy without guidance, using it alone is a poor match. Raw cut leaf or a paired formula, and whether it belongs in a prescription, should be decided by a licensed Chinese medicine practitioner after pattern diagnosis.

Shi Wei: Materia Medica Profile

Identification & Quality Standard

Pyrrosiae Folium

Botanical Origin

The dried leaf of Pyrrosia sheareri (Bak.) Ching, Pyrrosia lingua (Thunb.) Farwell, Pyrrosia petiolosa (Christ) Ching. (Polypodiaceae).

Production Regions

Primarily produced in eastern, central and northeastern China.

Quality Requirements

Superior medicinal material has intact leaf, thick and large, red back side with small spots.

Macroscopic Features

Pyrrosia sheareri (Bak.) Ching: Leaf is slightly wrinkled, lanceolate shape after being flattened, 10~25cm long, 3~5cm wide. Apex is gradually pointed, base is ear-like and sloped, entire, edge often rolled inward; upper surface is yellowish-green or grayish-green, scattered black round small indented spots; lower surface has dense reddish-brown star-like hairs, sometimes has an interval of side veins with many brown round spotted spores. Leaf stem has 4 ridges, 10~20cm long, 1.5~3mm diameter, slightly curved, with longitudinal grooves. Leaf is leathery. faint odor, slightly astringent and bitter taste. Pyrrosia lingua (Thunb.) Farwell: Lanceolate or elliptical-lanceolate shape, 8~12cm long, 1~3cm wide, base is wedge-like shape, symmetrical. Spores are between the veins, arranged densely and even. Leaf stem is 5~10cm long, about 1.5mm diameter. Pyrrosia petiolosa (Christ) Ching: Often rolled in tubes, elliptical or oval-elliptical shape after flattened, 3~8cm long, 1~2.5cm wide, base is wedge-like and symmetrical. Lower surface side vein is indistinct, densely covered in spores. Leaf stem is 3~12cm long, about 1mm diameter.

Main Regions and Quality Identification

Traditional materia medica and industry experience value certain regions south of the Yangtze, but actual quality also depends on variety, harvest time, processing, and storage. The main regions include Zhejiang, Hubei, Hebei, and Jiangsu; the plant size and leaf thickness differ slightly by region. Good-quality raw Shi Wei has intact, leathery leaves, a smooth surface with a slight leathery feel, gray-green star-shaped hairs on the underside, a faint odor, and a slight bitter-astringent taste; the processed form is mostly the dried leaf cut into segments — the appearance is the same as the raw form, only a size adjustment. The common look-alikes are other ferns of the same family — such as Lu Shan Shi Wei and You Bing Shi Wei — to be distinguished carefully; the true medicinal Shi Wei must fit the variety range specified by the Pharmacopoeia of the People's Republic of China.

Traditional Properties & Historical Lineage

Nature, Flavour & Channel Tropism

Sweet, Salty; Slightly coldLungBladder

1. Records in Classic Materia Medica

Shen Nong Ben Cao Jing: lists Shi Wei as upper grade — "mainly treats labor-heat evil qi and the five strangury closed and unblocked; benefits urination and the water passage."
Ming Yi Bie Lu: adds that it can "stop vexation, descend qi, free bladder fullness, tonify the five strains, settle the five viscera, remove evil wind, and boost essence qi."
Xin Xiu Ben Cao: says it "mainly treats flooding with leaking blood and golden-wound blood leaking internally; stops pain and generates flesh."
Ben Cao Gang Mu: summarizes that it "mainly treats stool not passing and bladder evil qi, and treats back carbuncle sores."
De Pei Ben Cao: points out that it "clears the metal (lung), drains heat, frees water, and relieves strangury."
Zhong Hua Ben Cao: records that it can "promote urination, relieve strangury, clear heat, and stop bleeding."

2. How Views of Its Nature Changed

Views among physicians differ somewhat. Some, like the Ming Yi Bie Lu, mention a tonifying action — holding that it can "tonify the five strains and settle the five viscera"; but more later physicians — such as the De Pei Ben Cao — stress its clearing-draining character, emphasizing its use for the painful urination of dampness-heat pouring downward rather than a tonifying action. Some physicians think its scope is broad — usable for various dampness-heat-related patterns; others stress its cold nature — not for people with spleen-stomach deficiency-cold. This difference reflects Shi Wei's clear positioning as a clearing-draining herb, avoiding the misconception of treating it as a universal tonic.

Core Efficacies & Traditional Applications

Traditional Functions

Promotes diuresis and relieves stranguria, clears lung and stops cough, cools blood and stops bleeding.

1. First Direction: Promoting Urination and Relieving Strangury

Traditional action: clear the lower-jiao dampness-heat and free the water passage, improving the state of urination.
Typical signs: dampness-heat accumulating in the bladder — painful urination, dark-yellow urine, frequent but hesitant urination, even urine that will not pass at all.
Usual combinations: often paired with other dampness-heat-clearing herbs — such as Che Qian Zi and Qu Mai — to strengthen the clearing effect; if lower-jiao stasis accompanies, blood-activating, stasis-resolving herbs can be added.
Who should not self-use: those with spleen-stomach deficiency-cold — because Shi Wei is cold, it may worsen the deficiency-cold abdominal pain and diarrhea.

2. Second Direction: Clearing Heat and Stopping Bleeding

Traditional action: clear the lower-jiao dampness-heat to stop bleeding — mostly for the blood in the urine of dampness-heat damaging the lower-jiao vessels, or with a burning urethra.
Typical signs: urinary bleeding with blood in the urine, possibly with a hot, burning urethra.
Usual combinations: often paired with blood-cooling, hemostatic herbs — such as Xiao Ji and Bai Mao Gen — to strengthen the bleeding-stopping effect; if dampness-heat blockage accompanies, combine with diuretic, strangury-relieving herbs.
Who should not self-use: the bleeding of yin-deficiency fire-flaring — the cold nature may further damage the yin fluids and worsen the yin-deficiency symptoms.

3. Classic Pairing: Shi Wei With Che Qian Zi

Shi Wei with Che Qian Zi is a common pair — both have the promote-urination, relieve-strangury action; Shi Wei leans to clearing the lower-jiao dampness-heat while stopping bleeding, Che Qian Zi leans to clearing heat, freeing water, and brightening the eyes. Combined, they strengthen the clear-dampness-heat, free-water-passage action — fitting the painful urination with scanty, reddish urine of dampness-heat accumulating in the bladder. This pair needs the physician's pattern diagnosis — only after confirming the lower-jiao dampness-heat pattern can it be used; do not pair blindly 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 the plant include flavonoids (such as quercetin and kaempferol), triterpenoids, organic acids, polysaccharides, and small amounts of volatile oils. In in vitro experiments, some flavonoid constituents showed a certain inhibiting effect on some pathogenic bacteria; in animal experiments, the water extract of Shi Wei increased the urine output of rats — showing a certain diuretic effect. As for human clinical research, only a few small-sample studies have observed that, under a practitioner's pattern-differentiated guidance, Shi-Wei-related compound formulas may help improve some urinary-system symptoms — but larger human studies are still needed to verify this.

2. Current Research Directions

Current research on Shi Wei mainly focuses on the material basis of its diuretic action, its influence on urinary-system-related cells, and the in vitro antibacterial activity of some constituents:

Its diuretic action may relate to regulating the kidney-related ion transport.
In in vitro experiments, some flavonoid constituents can inhibit the growth of Escherichia coli and Staphylococcus aureus.

Research currently mainly explores its potential value in urinary-system regulation and the separation and identification of the active constituents.

3. Limitations of Current Research

Lab results are not clinical efficacy — in vitro and animal results cannot be directly equated with the effect after taking Shi Wei.
Extracts and monomers are not the same as traditional decoction pieces — the constituent concentration used in experiments differs greatly from the slice dose taken daily.
Doses and preparation methods vary between studies — the comparability of the results is limited.
A single component does not define the whole herb — Shi Wei's action is the result of many constituents working together; a single constituent's activity cannot represent the whole herb's effect.

Comparing Similar Herbs

1. What They Share

Choosing Qu Mai as the similar herb, the two share these points:

Both have the promote-urination, relieve-strangury action, and both are used for the traditional patterns of difficult urination and urethral pain from lower-jiao dampness-heat.
Both need pattern-differentiated use according to the constitution under a practitioner's guidance.
Both may appear in classic formulas for urinary discomfort.

2. The Key Differences: Shi Wei vs. Qu Mai

Nature and flavors: Shi Wei is cold with bitter and sweet flavors, entering the lung and bladder channels; Qu Mai is cold with a bitter flavor, entering the heart and small-intestine channels. Both are cold clearing-draining herbs, but Shi Wei carries a sweet flavor — able to attend to some lung-moistening — while Qu Mai mainly clears and discharges with the bitter flavor; the subtle nature difference affects the suited focus.
Focus: Shi Wei's core actions are promoting urination, relieving strangury, and clearing heat to stop bleeding — besides improving urination, it can be used for the lower-jiao bleeding of dampness-heat; Qu Mai's core actions are promoting urination, relieving strangury, and breaking the blood to free the channels — besides freeing the water passage, it can be used for the amenorrhea and dysmenorrhea of blood-stasis blockage. There is a clear difference between the stop-bleeding and activate-blood directions.
Qi tendency: Shi Wei's action leans sinking — mainly acting on the bladder channel, freeing the water passage and clearing the lower-jiao dampness-heat — its influence on qi movement is mainly making the lower-jiao qi flow through clearing; Qu Mai's action is also sinking, but it also acts on the heart channel — clearing heart fire, breaking stasis, and freeing the channels — with a more obvious regulation of qi-blood stasis.
Best fit: Shi Wei's traditional fit is painful urination with dark-yellow urine, possibly with blood in the urine — mostly without obvious blood-stasis manifestations; Qu Mai's traditional fit is dribbling, painful urination, possibly with the blood-stasis menstrual irregularity, amenorrhea, and abdominal pain — the fit includes blood-stasis-related symptoms.
Not suitable: Shi Wei's cold quality is stronger — those with spleen-stomach deficiency-cold and frequent abdominal pain or diarrhea should not use it; Qu Mai has a blood-breaking action — pregnant women and those with heavy menstruation should not use it; both are clearing-draining herbs — those with yin deficiency without dampness-heat should be cautious with either.
Use scenes: Shi Wei more often appears in the formulas for urinary bleeding and painful urination — such as the formulas for blood strangury; Qu Mai more often appears in the formulas combining menstrual regulation and urinary discomfort — such as the formulas for blood-stasis amenorrhea with difficult urination — more common in the scenes combining gynecological and urinary regulation.

3. One-Sentence Summary

Simply put, Shi Wei leans toward clearing the lower-jiao dampness-heat while also stopping bleeding, whereas Qu Mai leans toward clearing the lower-jiao dampness-heat while also activating blood. Both can be used for the lower-jiao dampness-heat pattern of painful urination, but they are not interchangeable.

Classical Formulas Containing Shi Wei

Classic Formula 1: Shi Wei San (Pyrrosia Powder)

Combination logic: In Shi Wei San, Shi Wei is the lord — performing the core action of promoting urination, relieving strangury, and clearing dampness-heat; Qu Mai and Che Qian Zi strengthen the clearing effect; Hua Shi clears heat and frees water; Dong Kui Zi slides and frees the orifices — the herbs work together to solve the dribbling, painful urination of dampness-heat accumulating in the lower jiao. Shi Wei is the core herb here, but it cannot be used alone — a single herb cannot attend to the multiple clearing needs, and the synergy of the other herbs is missing.

Traditional use: used to treat heat strangury and stone strangury — frequent urination, painful urination, blood in the urine, or urine that will not pass at all.

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 a urinary-system disease.

Classic Formula 2: Shi Wei Tang (Pyrrosia Decoction)

Combination logic: In Shi Wei Tang, Shi Wei is the lord — performing the clear-heat, stop-bleeding, promote-urination, relieve-strangury action; Xiao Ji and Bai Mao Gen strengthen the blood-cooling, bleeding-stopping effect; Pu Huang and Dang Gui activate the blood and dissolve stasis — the herbs work together to solve the urinary bleeding and urethral pain of lower-jiao dampness-heat damaging the vessels. Shi Wei is the core herb here, but it cannot be used alone — a single herb cannot attend to both the stop-bleeding and activate-blood needs, and the synergy of the other herbs is missing.

Traditional use: used to treat blood strangury — urinary bleeding with blood in the urine, with a hot, burning, painful urethra.

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 urinary bleeding.

Formulas vs. Single Herbs

A formula is the joint action of many herbs — through the lord-minister-assistant-envoy combination, it attends to multiple symptoms and mechanisms and achieves an overall regulating effect. A single herb cannot simply replicate a full formula's effect — its action is one-sided and cannot reach the formula's synergy. The doses and combinations in a formula are holistic — the dose ratios of the different herbs directly affect the formula's direction; casually adjusting may change its action. Do not build formulas from online articles — online information often lacks pattern-differentiated guidance and easily leads to medication that misses the pattern. The common misunderstanding: a herb that works in a formula does not mean taking it alone produces the same effect — the formula's action is the result of many constituents working together; the constituents and dose of the single herb differ from the formula's, so the effect also differs.

Diet & Daily Home Use

1. Home Tea

Tea — Shi Wei Che Qian Zi Cha: dried Shi Wei 5 g, Che Qian Zi 3 g. Wrap both in gauze, put into a thermos, steep in boiling water, cover 15 minutes, and drink. Suited to the daily regulation of mild dampness-heat — difficult urination with yellowish urine, without obvious urethral pain. Not for those with spleen-stomach deficiency-cold, frequent abdominal pain or diarrhea, or for pregnancy and breastfeeding women. Suggested: 2–3 times a week; do not drink continuously long-term. Note: Shi Wei is a medicinal slice — do not eat large amounts as an ordinary food; mind the difference between the slice and daily ingredients.

2. Decoction and Processing Differences

The difference between raw and processed: the raw Shi Wei mainly clears dampness-heat — fit for regulating the urinary discomfort of dampness-heat; the processing is mostly just cutting into segments — a size adjustment with no obvious functional difference from the raw form — no special processing needed. Shi Wei needs no pre-boiling, late addition, bag-boiling, or direct swallowing. The basic home method: wash the slices, put into the pot with enough clean water, and decoct 15–20 minutes. Different forms cannot be converted directly — the tea dose is far smaller than the medicinal prescription dose; do not equate the tea dose with the medicinal dose.

3. Dosage and Course

The common dose range in traditional prescriptions is 6–12 g — the exact dose must be adjusted according to the pattern-differentiation result. The difference between food and medicinal doses: the food dose is usually 1/2 to 1/3 of the medicinal dose, with gentle regulation as the principle. Long-term continuous use is not advised — generally do not use beyond 1 week; if the symptoms do not improve, consult a physician or pharmacist. Special groups — such as children, the elderly, and pregnant women — should have the dose and course adjusted under a physician's guidance.

Contraindications & Safety Warnings

1. Who Should Avoid It

Spleen-stomach deficiency-cold — frequent abdominal pain, diarrhea, and cold hands and feet — not for use, because the cold nature may worsen the deficiency-cold symptoms.
Pregnancy and breastfeeding — use cautiously; there is currently a lack of sufficient safety data.
Children and the elderly — weaker body metabolic ability — use under a physician's guidance.
Liver or kidney impairment — Shi Wei is metabolized through the liver and kidneys — consult a doctor before use.
Allergy to ferns — may have an allergic reaction to Shi Wei.
Those in special treatment — such as anticoagulants or blood-pressure medications — consult a doctor or pharmacist first, to avoid drug interactions.

2. Interactions and Diet Notes

Shi Wei may interact with anticoagulants, blood-pressure medications, and glucose-lowering medications — those taking such drugs should use cautiously, to avoid affecting the drug effect. 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.

3. Adverse Reactions and Overdose Risk

Shi Wei has relatively few adverse reactions, but overdose may bring abdominal pain and diarrhea in those with spleen-stomach deficiency-cold. If marked discomfort, allergy signs, persistent vomiting, breathing difficulty, altered consciousness, or rapidly worsening symptoms appear, stop at once and seek medical care.

Frequently Asked Questions About Shi Wei

What is Shiwei? Is it the same as Haijinsha or Cheqianzi?

Shiwei is the dried leaf of Pyrrosia sheareri, Pyrrosia lingua or Pyrrosia petiolosa, Latin name Pyrrosiae Folium. It is a common Chinese medicine centered on promoting urination to relieve strangury, clearing the lung and stopping cough, and cooling the blood to stop bleeding. Haijinsha promotes urination and relieves pain for stone strangury. Cheqianzi promotes urination for heat strangury. They cannot be used interchangeably in equal amounts. Prescribe as Shiwei. Caution in yin deficiency without damp-heat.

What are the composition and effects of Shiwei?

Pharmacopoeial name Shiwei, Latin Pyrrosia sheareri (Bak.) Ching etc. Sweet and bitter in taste, slightly cold in nature, enters the Lung and Bladder meridians. Functions to promote urination to relieve strangury, clear the lung and stop cough, and cool the blood to stop bleeding. Used for heat strangury, blood strangury, stone strangury, urinary obstruction, lung heat cough and dyspnea, hematemesis and epistaxis. Promotes urination and clears the lung.

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

Leaves are used raw. Haijinsha emphasizes stone strangury rather than strongly clearing the lung, and cannot replace it in equal amounts. Commercial products are standardized; do not adjust arbitrarily.

What is the dosage of Shiwei? Can it be used daily as a strangury-relieving tea?

Decoction, 9-15g. Modern use requires physician-determined dosage. It is not a year-round "Shiwei tea." Yin deficiency without damp-heat will be further injured by prolonged use. Strangury requires short-term, physician-determined dosage and cannot replace evaluation.

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

Not suitable for yin deficiency without damp-heat. Pregnant women require physician evaluation. Stop if dry mouth or lumbar soreness occur. Seek immediate medical care for severe stones or high fever.

Can Shiwei promote urination, clear the lung, and stop bleeding?

It can assist heat strangury, blood strangury, stone strangury, urinary obstruction, lung heat cough and dyspnea, hematemesis and epistaxis. It promotes urination to relieve strangury, clears the lung and stops cough, and cools the blood to stop bleeding, but is not a specific remedy for all strangury or all cough.

Can Shiwei be taken daily as a strangury-relieving or cough-stopping tea?

Damp-heat strangury can be used short-term in formulas; yin deficiency without damp-heat will be further injured. The idea that "Shiwei must promote urination" cannot replace evaluation. Promoting urination and clearing the lung requires physician-determined formulation and dosage.

How to choose between Shiwei, Haijinsha, Cheqianzi, Jinqiancao, and Qumai?

Shiwei promotes urination and clears the lung, suited to stone strangury. Haijinsha promotes urination and relieves pain for stone strangury. Cheqianzi promotes urination for heat strangury. Jinqiancao drains dampness and promotes urination. Qumai promotes urination for blood strangury. Choose Shiwei for promoting urination; Haijinsha for relieving pain; Cheqianzi for heat strangury; Jinqiancao for stones; Qumai for blood strangury. Pattern differentiation applies, but large doses of Shiwei are contraindicated in yin deficiency without damp-heat.

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

Modifications depend on the pattern. Add Jinqiancao for stone strangury; add Huangqin for lung heat. Specify Shiwei; do not substitute Haijinsha in equal amounts for clearing the lung.

How to select and store Shiwei?

Choose regular Chinese medicinal materials with intact leaves. Discard if moldy, damp, or abnormal in odor. Store in a dry place. Purchase "Shiwei"; do not substitute Haijinsha or Cheqianzi in equal amounts for promoting urination, clearing the lung, and stopping bleeding.

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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.