Fruits and seedsTonifyingFructus Psoraleae

Bu Gu Zhi (Psoralea Fruit)

A practical guide to Bu Gu Zhi: 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 Sep 25, 2026

Quick Facts

Latin NameFructus Psoraleae
Chinese Name & Pinyin 補骨脂 · Bu Gu Zhi
Medicinal PartFruits and seeds
The herbBu Gu Zhi is the dried ripe fruit of psoralea. Common forms: raw and salt-fried. External products are usually a prepared tincture or powder from a clinic. Home-soaked wine is not a protocol.
Nature and channelsAcrid, bitter, warm. Enters the Kidney and Spleen. Acrid warmth fortifies the lower origin and helps hold what is slipping.
Pharmacopoeia lineWarms Kidney yang, grasps qi, and stops diarrhea. Used for impotence and seminal emission, frequent urination or enuresis, cold lumbar and knee pain, Kidney-deficiency wheezing, and fifth-watch diarrhea. External use for vitiligo and alopecia areata.
Pattern cuesCold low back and knees. Impotence or emissions. Frequent night urine. Exertional wheeze. Dawn diarrhea. Fear of cold. Pale tongue with white coating.
In this articleRaw versus salt-fried Bu Gu Zhi. How it differs from Du Zhong, Rou Dou Kou, and Wu Wei Zi. Why yin-deficiency fire is a stop sign. Photosensitivity, liver-function caution, and who should skip it.

What Is Bu Gu Zhi?

Bu Gu Zhi (补骨脂; Bǔ Gǔ Zhī; Latin: Psoraleae Fructus; English: psoralea fruit) is the dried ripe fruit of Psoralea corylifolia L. (now often Cullen corylifolium). In Chinese medicine it is a warm yang-tonifying herb. It is acrid, bitter, and warm, enters the Kidney and Spleen channels, and its core actions are to warm Kidney yang, grasp qi and calm wheezing, and warm the Spleen and stop diarrhea. Used externally, it may dispel wind and fade pale patches. Older names include po-gu-zhi and black scurfpea.

It is used most often for three patterns:

  • Kidney yang deficiency — cold low-back and knee pain, impotence or seminal emission, frequent urination or enuresis
  • Kidney failing to grasp qi — wheezing worse on exertion, more exhalation than inhalation
  • Spleen–Kidney yang deficiency — fifth-watch diarrhea (pain and loose stools before dawn)

The raw fruit is more drying and warming. Salt-fried Bu Gu Zhi is milder and guided to the Kidney, and is used more often to grasp qi and stop diarrhea. The usual decoction dose is 6–10 g. It is a poor fit in yin-deficiency fire or dry, bound stools.

External use for vitiligo or alopecia areata needs a practitioner. Avoid strong sun after topical use. Case reports of liver injury exist with long-term or high-dose self-use. This is not a daily “yang snack.”

Bu Gu Zhi warms Spleen and Kidney yang, which is why it appears in Si Shen Wan. It is warm and drying. Tidal heat, night sweats, and a red dry tongue are the wrong picture. Not every “kidney weakness” is an indication.

Bu Gu Zhi is not a catch-all for low energy, night urine, or diarrhea. In yin-deficiency heat, known liver disease, or fatigue without yang-deficiency signs, using it alone can stir fire and burden the liver. Internal or external use should be decided by a licensed Chinese medicine practitioner after pattern diagnosis. Do not take it long-term on your own.

Bu Gu Zhi Psoralea Fruit

Bu Gu Zhi: Materia Medica Profile

Identification & Quality Standard

Fructus Psoraleae

Botanical Origin

The dried mature fruit of Psoralea corylifolia L.(Fabaceae)

Production Regions

Primarily produced in Chinese provinces of Henan, Sichuan, Anhui.

Quality Requirements

Superior medicinal material is large, full, black.

Macroscopic Features

Fruit is flat round and kidney-shaped; one end relatively pointy, rare persistent calyx. Huai bu gu zhi is 4~5.5mm long, 2~4mm wide, 1mm thick; chuan bu gu zhi is relatively small. Externally blackish-brown or brown, with intricate net-like wrinkles. Relatively hard and brittle texture. After being broken, fruit skin and seed outer coat are tightly connected, the seed indented side has spotted hilum below the apex, chalaza at the other end, unobvious raphe. Outer skin is harder, inner is membranous, grayish-white; 2 cotyledons, thick, pale yellow to pale yellowish-brown, getting darker with prolonged storage. White material can be seen on both surfaces as small needle-like crystals when magnified. Embryo is extremely small. Connected petiole bases, with 5 breaches, grayish-yellow, hairy, with dense brown gland points. Distinctive aromatic odor; taste slightly acrid.

Authentic Regions (Dao Di) & Quality Identification

  • Traditional Origins: Historically sourced from regions like Henan, Sichuan, and Anhui. Quality is heavily influenced by harvest time and processing methods.
  • Signs of Quality: Premium Bu Gu Zhi (Psoralea Fruit) features hard, flat, and dark brown seeds.
  • Aroma & Taste: It has a fragrant scent with a spicy and slightly bitter taste. The salt-fried version will be slightly darker and have a mildly salty taste. While fakes are rare, purchasing from reputable sources ensures purity.

Traditional Properties & Historical Lineage

Nature, Flavour & Channel Tropism

Acrid, Bitter; WarmKidneySpleen

1. Historical Records

  • Classic Texts: The ancient text Kai Bao Ben Cao notes its use for exhaustion, internal cold, bone marrow damage, and Kidney coldness. The famous Ben Cao Gang Mu highlights its ability to treat cold-type diarrhea, warm the Dan Tian (lower abdomen), and gather vital spirit.

2. Evolution of Medicinal Understanding

  • Shifting Focus: TCM practitioners universally recognize it as a core herb for treating Kidney Yang deficiency. Some experts focus heavily on its warming and tonifying power, while others emphasize its astringent ability to treat bedwetting or frequent urination.
  • Safety Cautions: Because of its noticeably warm and hot nature, traditional practitioners carefully control the dosage to prevent adverse reactions like internal heat or dryness from over-warming.
Bu Gu Zhi Psoralea Fruit

Core Efficacies & Traditional Applications

Traditional Functions

Warms kidney, assists yang, promotes qi absorption, regulates gasping, warm spleen, relieves diarrhea. Deficiency of kidney yang, cold of low, cold pain of waist and knees, impotence and seminalemission, frequent urination, urine emission, loose qi due to kidney, deficiency and gasping, deficiency of spleen and kidney, chronicle diarrhea, vitiligo, alopecia areata, psoriasis.

1. Primary Focus: Tonifying Kidney and Strengthening Yang

  • Traditional Efficacy: Traditionally used for tonifying the Kidney and strengthening Kidney Yang.
  • Target Symptoms: Commonly applied for conditions caused by Kidney Yang deficiency, which often manifest as soreness and weakness in the lower back and knees, an aversion to cold, and reproductive issues like impotence or premature ejaculation.
  • Common Combinations: Frequently paired with herbs like Tu Si Zi (Dodder Seed) and Du Zhong (Eucommia Bark) to enhance its Kidney-warming effects.
  • Caution: Individuals with Yin deficiency and excessive fire (showing signs of heat and dryness) should not use this without professional guidance, as its warming nature can aggravate these symptoms.

2. Secondary Focus: Securing Essence and Reducing Urination

  • Traditional Efficacy: Acts as an astringent to secure essence and reduce frequent urination.
  • Target Symptoms: Mostly used for managing symptoms like frequent urination, enuresis (bedwetting), and spermatorrhea.
  • Common Combinations: Often used alongside Yi Zhi Ren (Alpinia Oxyphylla Fruit) or Sang Piao Xiao (Mantis Egg-case).
  • Caution: If urinary frequency is caused by damp-heat in the lower burner (often mimicking an active infection), this herb should be avoided as it can trap the dampness and generate more heat.

3. Common Single Herb Pairs: Herb Relationships

  • Bu Gu Zhi + Yi Zhi Ren: A classic TCM herb pair. Bu Gu Zhi (Psoralea Fruit) focuses on tonifying Kidney Yang and securing essence, while Yi Zhi Ren (Alpinia Oxyphylla Fruit) warms the Spleen and Kidneys to assist in this securing action.
  • Synergy: Together, they strongly enhance the body's ability to tonify the Kidneys and reduce urination. This combination is highly effective for traditional syndromes of Kidney Yang deficiency paired with frequent urination or bedwetting.
  • Note: This pairing requires proper TCM pattern diagnosis and should not be mixed casually at home.
Bu Gu Zhi Psoralea Fruit

Modern Research

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

1. Key Chemical Components

  • Active Ingredients: Rich in coumarins, flavonoids, and volatile essential oils.
  • Lab Findings: Test-tube studies indicate that certain components possess mild antibacterial and anti-inflammatory properties.
  • Physiological Support: Animal studies suggest it can improve symptoms linked to Kidney Yang deficiency and boost immune function. However, robust human clinical trials are still needed to map out its exact mechanisms in the human body.

2. Modern Pharmacological Focus

  • Current Research: Modern science is exploring its potential in supporting bone health (anti-osteoporosis) and regulating blood lipids by interacting with specific cellular signaling pathways.
  • Ongoing Studies: Scientists are currently focusing on isolating active compounds for potential chronic disease management, though clinical safety and efficacy in humans require further validation.

3. Limitations of Modern Research

  • Lab vs. Real Life: Results from animal studies or test tubes cannot be directly translated to human patients.
  • Extracts vs. Whole Herb: Isolated, concentrated chemicals do not behave the same way as traditional herbal decoctions.
  • Inconsistent Methods: Different studies use varying dosages and extraction methods, making it hard to compare results uniformly.
  • Synergy is Key: In TCM, the holistic combination of all compounds within Bu Gu Zhi (Psoralea Fruit) creates its complex therapeutic effect. Evaluating the herb based on a single chemical component misses the complete picture.
Bu Gu Zhi Psoralea Fruit

Comparing Similar Herbs

1. Common Ground: Bu Gu Zhi vs. Yin Yang Huo

  • Both Bu Gu Zhi (Psoralea Fruit) and Yin Yang Huo (Epimedium) tonify the Kidneys and are used to improve symptoms related to Kidney deficiency.
  • Both are frequently found in formulas or dietary therapies aimed at warming the Kidneys.
  • Both require careful consideration of a person's constitution and correct dosage to avoid improper use.

2. Core Differences

  • Properties & Natures: Bu Gu Zhi is spicy, bitter, and warm, leaning heavily towards warm tonification. Yin Yang Huo is spicy, sweet, and warm; its drying nature is slightly milder, but it possesses a strong ability to dispel wind and dampness.
  • Core Strengths: Bu Gu Zhi focuses intensely on tonifying Kidney Yang, securing essence, and reducing urination. Yin Yang Huo excels at tonifying Kidney Yang while also strengthening bones and sinews, making it superior for treating rheumatic joint pain combined with Kidney deficiency.
  • Direction of Action: Bu Gu Zhi has a descending and sinking energetic nature, focusing on locking in essence. Yin Yang Huo has an ascending and dispersing nature, helping to stimulate and lift Yang energy.
  • Target Symptoms: Choose Bu Gu Zhi for cold pain in the lower back and knees with frequent urination. Choose Yin Yang Huo for impotence, weak limbs, and rheumatic pain linked to Yang deficiency.
  • Contraindications: Bu Gu Zhi is strictly avoided in Yin deficiency with fire. Yin Yang Huo is avoided in Yin deficiency where the "ministerial fire" is hyperactive.

3. Summary of Differences

In short: Bu Gu Zhi (Psoralea Fruit) is highly focused on tonifying Kidney Yang and acting as an astringent for bodily fluids. Yin Yang Huo (Epimedium) has a broader action, adding the benefits of strengthening bones and clearing wind-dampness. While both treat Kidney Yang deficiency, they are not simply interchangeable.

Bu Gu Zhi Psoralea Fruit

Classical Formulas Containing Bu Gu Zhi

3 Formulas vs. Single Herbs

  • Synergy is Key: A formula is a balanced team. The healing power comes from how the herbs interact, so a single herb cannot simply replicate a full formula's effects.
  • Holistic Balance: The exact dosage and combination in a formula affect the entire body. Never try to mix or alter these formulas at home based on internet articles.

Diet & Daily Home Use

1. Home Recipes & Teas

  • Bu Gu Zhi and Walnut Porridge:
    • Ingredients: 10g Bu Gu Zhi (Psoralea Fruit), 30g walnuts, and an appropriate amount of rice.
    • Method: Wash the herb, crush the walnuts, rinse the rice, and simmer everything together in water until it forms a porridge.
    • Application: Ideal for those with Kidney Yang deficiency experiencing lower back and knee weakness. Consume 2-3 times a week.
    • Caution: Not suitable for those with Yin deficiency and excessive fire. Because this is a medicinal herb, keep servings moderate and do not consume in excessively large amounts.

2. Preparation & Brewing Differences

  • Processing Matters: Raw Bu Gu Zhi tends to move toward the exterior and excels at warming the Kidneys to boost Yang. The salt-fried version (processed with saltwater) directs the herb's action deeper into the Kidneys, specifically enhancing its ability to secure essence.
  • Brewing Basics: It generally does not require special brewing methods (like pre-boiling or wrapping) and can be decocted conventionally with other herbs using low heat to reach the right concentration.
  • Forms Matter: Dosages for teas or decoctions cannot be directly translated to pills or powders, as their absorption and strength differ.

3. Dosage & Usage Cycle

  • Standard Range: Typical clinical doses in a prescription range from 6 to 10 grams.
  • Dietary vs. Medical Use: Doses used in home cooking (like porridge) should be kept on the lower end, whereas medicinal doses are determined by a doctor based on your condition.
  • Cycle: It is not recommended for long-term, continuous use to prevent heat accumulation or adverse reactions.
  • Vulnerable Populations: Pregnant women, children, the elderly, and those with compromised liver or kidney function must consult a healthcare provider before use.
Bu Gu Zhi Psoralea Fruit

Contraindications & Safety Warnings

1. Who Should Avoid It

  • Yin Deficiency: Those with Yin deficiency and internal heat must avoid it, as its warm nature will severely aggravate symptoms like dry mouth or night sweats.
  • Special Populations: Strictly contraindicated for pregnant and nursing women, as its heating properties may impact fetal or infant health. Children and the elderly should only use it under strict medical supervision.
  • Organ Health: Individuals with abnormal liver or kidney function should use it with extreme caution to avoid adding stress to these organs.
  • Allergies & Medications: Anyone allergic to the plant family must avoid it. If you are taking specific treatments like blood thinners or blood pressure medications, consult a doctor before use.

2. Medication Clashes & Dietary Notes

  • Interaction Risks: Bu Gu Zhi (Psoralea Fruit) may interact with modern pharmaceuticals. For example, it might alter blood coagulation if taken with anticoagulants, or interfere with the efficacy of blood pressure and blood sugar medications.
  • Professional Review: While there is little evidence of general "food clashing," active herbal components can interact with prescription drugs. Always inform your doctor or pharmacist if you are combining this herb with western medications.

3. Adverse Reactions & Overdose Risks

  • Common Signs: Minor adverse reactions can include dry mouth, bitter taste, or mild nausea.
  • When to Seek Emergency Care: Stop usage immediately and seek medical help if you experience severe allergic reactions, persistent vomiting, difficulty breathing, altered consciousness, or any rapid worsening of your symptoms.

Frequently Asked Questions About Bu Gu Zhi

What is Bu Gu Zhi? Are po gu zhi and hu jiu zi the same herb?
Bu Gu Zhi (补骨脂) is the dried ripe fruit of Psoralea corylifolia L. (also Cullen corylifolium). The pharmacopoeial name is Psoraleae Fructus. Older names include po-gu-zhi (破故纸), po-gu-zhi (婆固脂) and hu jiu zi. It is a Kidney-Yang tonic, not a snack. The characters “mend-bone-fat” must not be read as a license to chew it like a health nut.
What are the TCM properties and traditional uses of Bu Gu Zhi?
According to the Chinese Pharmacopoeia, Bu Gu Zhi is acrid, bitter and warm, enters the Kidney and Spleen channels, and acts to warm Kidney Yang, grasp Qi and calm wheezing, and warm the Spleen to stop diarrhea. It is used for Kidney-Yang insufficiency with impotence, seminal emission, frequent urination, cold lumbar and knee pain, deficient wheezing and cock-crow diarrhea. Topically it dispels wind and helps pigment in vitiligo and alopecia areata. It is acrid-warm and drying: it stokes Ming Men fire and warms Earth.
What is the difference between raw and salt-fried Bu Gu Zhi?
Raw Bu Gu Zhi is more acrid, warm and drying, stronger to warm Spleen and Kidney and stop diarrhea; the raw form is also common topically. Salt-fried Bu Gu Zhi is the usual official processed form: salt guides it to the Kidney, softens dryness and is preferred for impotence, cold lumbar pain, deficient wheezing and dawn diarrhea. Internal use is mostly the salted slice. Home pan-frying does not replace official processing and does not cancel liver-injury or photosensitivity risk.
What is the usual dosage of Bu Gu Zhi?
The common internal dose is 6–10 g in decoction; it may also enter pills or powders. Topically use a suitable amount as a wine soak or tincture. Reduce or avoid the dose in children, older adults and anyone with abnormal liver tests. Courses should be short; do not self-prescribe high-dose monotherapy. Patent medicines that already contain Psoralea must not be stacked.
What are the key safety issues and contraindications?
Contraindicated in Yin-deficiency fire and dry bound stool; avoid in pregnancy. It is warm and drying. Modern reports link high-dose or prolonged use with drug-induced liver injury—do not use it if there is known liver disease, jaundice or unexplained fatigue, and watch for anorexia, dark urine or yellow skin. It contains psoralens and is photosensitising by mouth and on the skin: use sun protection and do not add other photosensitising drugs. Stop and seek care for rash, blisters or right-upper-quadrant discomfort.
Can Bu Gu Zhi tonify the Kidney and treat low back pain?
The traditional target is Kidney Yang deficiency: cold lumbar and knee pain, aversion to cold, impotence, frequent night urination. It is not a generic backache or osteoporosis supplement, and not an over-the-counter aphrodisiac. Night sweats, a red dry tongue or Liver-Yang hypertension may worsen. Progressive bone pain or fracture risk still needs imaging and specialist care.
Why is Bu Gu Zhi used for cock-crow diarrhea and deficient wheezing?
Dawn diarrhea from Spleen-Kidney cold is treated by warming Kidney and Spleen, classically with nutmeg, Schisandra and Evodia in Si Shen Wan. Deficient wheezing from Kidney failing to grasp Qi—shortness of breath on exertion, more exhalation than inhalation—may be helped with walnut in Qing E Wan–type formulas. Damp-heat diarrhea, exterior wheezing and an asthma attack are the wrong patterns.
What should one watch for when using Bu Gu Zhi topically for vitiligo?
Topical use relies on photosensitisation and “dispelling wind to aid pigment” in vitiligo and alopecia areata, usually as a tincture or wine soak. Limit sun and UV exposure—overdose of light causes burn, blisters and extra pigment. Avoid broken or acutely inflamed skin. Vitiligo belongs under dermatology; topical Psoralea does not replace supervised phototherapy, and oral herb is not a “pigment supplement.”
Which herbs is Bu Gu Zhi combined with? What are the representative formulas?
With nutmeg, Schisandra and Evodia it forms Si Shen Wan for dawn diarrhea. With Eucommia and walnut it appears in Qing E Wan–type Kidney-bone formulas. For grasping Qi it may join walnut and fluorite. Keep courses short, do not stack Psoralea-containing patents, use sun protection, and tell the prescriber about other medicines, especially those handled by the liver.
How do you choose and store Bu Gu Zhi?
Choose full, hard, blackish-brown fruits with a distinctive odor. Salt-fried pieces look darker and may show a light salt frost. Store sealed and dry, protected from insects. Discard moldy, oily or sour lots. Buy only labeled Bu Gu Zhi or salt-fried Bu Gu Zhi from a regulated supplier—not anonymous “Yang-tonic powder” or folk vitiligo powder for self-ingestion.

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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.

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Bu Gu Zhi (Psoralea Fruit): Warm Kidney Yang, Grasp Qi, and Firm the Spleen