Herb

Long Kui

Black nightshade herb | 龙葵

Also known as:

Kǔ Cài (苦菜) , Kǔ Kuí (苦葵) , Tiān Qié Zi (天茄子)

Long Kui

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Properties

Heat-clearing herbs · Cold

Traditionally supports*

Skin Health Urinary Health Immune Support Inflammation Support

Parts Used

Whole plant / Aerial parts (全草 quán cǎo)

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

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About This Herb

Traditional Chinese Medicine background and properties

Herb Description

Long Kui (black nightshade) is a cooling herb used in Chinese medicine primarily for hot, inflamed conditions like boils, abscesses, skin infections, and sore throat. It also helps with difficult urination and swelling, and is widely used in China as a supportive herb alongside conventional cancer treatments. Because it contains small amounts of potentially toxic alkaloids, it should only be used under professional guidance.

Herb Category

Heat-clearing herbs Herbs that clear Heat and resolve Toxicity (清热解毒药)

Main Actions

  • Clears Heat and Resolves Toxicity
  • Invigorates Blood and Reduces Swelling
  • Promotes Urination and Reduces Edema
  • Cools the Blood and Stops Bleeding
  • Dissipates Nodules and Softens Hardness

How These Actions Work

'Clears Heat and resolves toxins' is Long Kui's primary action. Being Cold in nature and Bitter in taste, it powerfully drains Heat and eliminates toxic accumulations from the body. In practice, this means it is used for hot, inflamed conditions like boils, abscesses, sore throat, and skin infections (erysipelas, eczema). The bitter taste drives downward and dries Dampness, while the Cold nature directly opposes pathogenic Heat. This action also underlies its modern clinical use as a supportive herb in cancer treatment, where the accumulation of Heat-toxins is understood as a key factor in tumour formation.

'Invigorates Blood and reduces swelling' means Long Kui can move stagnant Blood and disperse swelling in injured or inflamed tissues. This is why classical texts such as the Ben Cao Zheng Yi describe it as "an excellent herb for surgery to clear Heat and reduce swelling" and note its use for traumatic injuries with bruising and Blood stasis. It can be applied topically as a poultice for swollen, painful injuries or sores.

'Promotes urination and reduces edema' reflects Long Kui's ability to open the water pathways through the Bladder channel. When Heat or Dampness accumulates in the lower body causing painful, scanty, or burning urination and edema, Long Kui helps by clearing the Heat and facilitating the passage of urine. This action connects directly to its use in acute kidney inflammation with swelling and reduced urine output.

'Cools Blood and stops bleeding' indicates that when Heat enters the Blood level, causing it to move recklessly and producing symptoms like vomiting blood or heavy uterine bleeding, Long Kui's Cold nature can cool the Blood and help stop the bleeding.

Patterns Addressed

In TCM, symptoms cluster into recognizable patterns of disharmony that reveal what's out of balance in the body. Long Kui is traditionally associated with these specific patterns.

The following describes this herb's classification within Traditional Chinese Medicine theory and is provided for educational purposes only.

Why Long Kui addresses this pattern

Toxic Heat is a pattern where pathogenic Heat concentrates and produces visible inflammation, often manifesting as painful red swellings, abscesses, boils, or infected sores. Long Kui is Cold in nature and Bitter in taste, giving it a strong downward-draining and Heat-clearing action. It enters the Bladder channel, which governs the body's lower waterways, but its toxin-resolving action has broad reach across skin and soft tissues. The herb directly counteracts the intense Heat and toxic accumulation at the root of this pattern, while its Blood-invigorating property helps disperse the local swelling and stagnation that accompany purulent infections.

A practitioner would look for one or more of these signs

Boils

Red, hot, painful skin abscesses

Skin Infection

Infected sores or carbuncles with pus

Sore Throat

Swollen, painful throat from Heat-toxins

Erysipelas

Fiery red skin rash (erysipelas / 丹毒)

TCM Properties

Temperature

Cold

Taste

Bitter (苦 kǔ), Sweet (甘 gān)

Channels Entered
Urinary Bladder
Parts Used

Whole plant / Aerial parts (全草 quán cǎo)

This is partial information on the herb's TCM properties. More detailed information is available on the herb's dedicated page

Product Details

Manufacturing, supplier, and product specifications

Product Type

Granules

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Botanical & Sourcing

Quality Indicators

Good quality dried Long Kui should have abundant leaves that are green or brownish-green in colour, with tender young stems. The stems should be hollow and cylindrical with visible surface wrinkling. Any remaining berries should be spherical with wrinkled brownish-yellow to brownish-black skin. The herb should have no significant odour, and the berries should taste bitter with a slight sourness. Preferred specimens are those with more leaves and less woody stem material. Avoid specimens that are yellowed, excessively dried and crumbly, or show signs of mould.

Primary Growing Regions

Long Kui (Solanum nigrum) is widely distributed across temperate to tropical regions of Europe, Asia, and the Americas. In China, it grows in nearly every province, commonly found along roadsides, field edges, wastelands, streambanks, and at forest margins. Unlike many Chinese herbs, Long Kui does not have a strongly defined dao di (terroir) region, as it is an extremely common and adaptable weed. It is native to Southeast Asia and has naturalized worldwide. The herb is collected from wild populations rather than being cultivated as a specialty crop in any particular region.

Harvesting Season

Summer and autumn (typically June to October), harvested as the whole above-ground plant, used fresh or dried.

Supplier Information

Treasure of the East

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Miscellaneous Info

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Usage & Safety

How to use this herb and important safety information

Important Medical Disclaimer

The information provided here is for educational purposes only and is not intended as medical advice or to replace consultation with a qualified healthcare professional. This herb is a dietary supplement and has not been evaluated by the FDA. It is not intended to diagnose, treat, cure, or prevent any disease.

Always consult with a qualified healthcare provider, particularly if you are pregnant, nursing, have a medical condition, or are taking other medications. Discontinue use and consult your healthcare provider if you experience any adverse reactions.

Recommended Dosage

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Instructions for safe storage and consumption

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Traditional Dosage Reference

Standard

15-30g

Maximum

Up to 30g (dried herb) or 60g (fresh herb) in decoction under practitioner supervision. Do not exceed without careful monitoring due to glycoalkaloid toxicity risk.

Notes

The standard decoction dose is 15 to 30g of the dried herb, or double (30-60g) when using fresh material. For external use, an appropriate amount of fresh herb is pounded and applied as a poultice, or the decoction is used as a wash. For chronic bronchitis, clinical reports have used approximately 30g dried whole herb daily (as a prepared tablet formulation) in 10-day treatment courses with 5-7 day rest intervals between courses. For anti-cancer applications in Chinese clinical practice, Long Kui is typically used in larger doses (up to 60g of fresh herb) combined with other herbs such as Bai Hua She She Cao, She Mei, and Bai Ying, always under close practitioner supervision. Due to its slight toxicity, treatment courses should be kept as short as clinically necessary. The herb has a mild stimulant quality (the classical texts note it 'reduces drowsiness'), so it is best taken during daytime rather than evening.

Toxicity Classification

Slightly toxic

Long Kui contains glycoalkaloids, primarily solanine, solasonine, and solamargine. These compounds are most concentrated in the unripe green berries (up to 4.2% alkaloid content) and decrease as the plant matures. Solanine acts similarly to saponins and can lyse (destroy) red blood cells. Overdose symptoms include headache, abdominal pain, nausea, vomiting, diarrhea, dilated pupils, heart rate irregularities (initially fast then slow), confusion, and in severe cases coma. Fatalities have been reported in children who ate unripe fruit. The toxicity mechanism involves cholinesterase inhibition and cell membrane disruption. At standard medicinal dosages (15-30g of dried herb in decoction), the toxicity is mild and clinically manageable. Boiling in decoction partially destroys solanine (it is nearly insoluble in water). The herb should be used for limited courses and discontinued once the acute Heat-toxin condition resolves. In cases of suspected overdose, gastric lavage with strong tea water is a traditional first-aid measure, followed by symptomatic treatment similar to that for sprouted potato poisoning.

Contraindications

Caution

Spleen and Stomach deficiency-cold (脾胃虚寒): Long Kui is bitter and cold in nature. People with cold-type digestive weakness, chronic loose stools, or poor appetite due to Spleen-Stomach Yang deficiency should avoid internal use, as it can further damage digestive function.

Avoid

Pregnancy: The glycoalkaloids in Long Kui (particularly solanine) have been shown in toxicological studies to affect embryonic development, with potential for miscarriage and birth defects. Avoid use during pregnancy.

Avoid

Consumption of unripe (green) fruit: The unripe green berries of Solanum nigrum contain the highest concentration of toxic glycoalkaloids. Ingesting unripe fruit can cause serious poisoning including vomiting, diarrhea, pupil dilation, confusion, and in severe cases coma or death (particularly dangerous in children). Never eat unripe Long Kui fruit.

Caution

Excessive or prolonged use: Due to its slight toxicity, Long Kui should not be taken at high doses or for extended periods without practitioner supervision. Overuse may lead to reduced white blood cell counts and elevated blood sugar. Discontinue once the Heat-toxin condition has resolved.

Caution

Diabetes or blood sugar concerns: Long Kui alkaloids (solanine, solasonine) have been shown to raise blood sugar levels in pharmacological studies. People with diabetes or impaired glucose tolerance should use with caution.

Special Populations

Pregnancy

Contraindicated during pregnancy. Toxicological studies have confirmed that solanine and related glycoalkaloids in Long Kui can affect embryonic development, potentially causing miscarriage and birth defects. Solanine glycoalkaloids have been shown to disrupt cell membranes and inhibit cholinesterase, mechanisms that pose direct risk to fetal development. Pregnant individuals should strictly avoid this herb in any form.

Breastfeeding

Not recommended during breastfeeding. Long Kui contains glycoalkaloids (solanine, solasonine, solamargine) that have a relatively long clearance time in the body (over 24 hours, meaning they can accumulate). While there are no specific studies on transfer of these alkaloids through breast milk, the known toxicity profile and the sensitivity of infants to even low doses of glycoalkaloids make it prudent to avoid this herb while nursing.

Pediatric Use

Use with great caution in children. Children are more susceptible to glycoalkaloid toxicity than adults, and there have been reports of fatalities in children who consumed unripe Long Kui berries. If prescribed for a child by a qualified practitioner (for example, for skin conditions as described in classical sources), the dosage should be significantly reduced from the adult range, typically one-third to one-half depending on age and body weight. External application (as a poultice of fresh herb) is generally safer for children than internal use. Never allow children to eat unripe green berries of this plant.

Drug Interactions

Hypoglycaemic agents: Long Kui alkaloids (solanine, solasonine) have been shown in pharmacological studies to raise blood sugar. This could potentially counteract the effects of insulin, metformin, sulfonylureas, or other glucose-lowering medications. Blood glucose should be monitored if Long Kui is used alongside diabetes medications.

Cholinesterase inhibitors: Solanine glycoalkaloids inhibit cholinesterase activity. Concurrent use with cholinesterase inhibitor drugs (such as donepezil, rivastigmine, or neostigmine, used for Alzheimer's disease or myasthenia gravis) could theoretically produce additive cholinergic effects or unpredictable interactions.

Anticoagulant or antiplatelet medications: Long Kui has traditional blood-activating (huo xue) properties. While the clinical significance is not well studied, caution is warranted when combining with warfarin, heparin, or antiplatelet drugs, as there may be an additive effect on bleeding risk.

Note: Formal drug interaction studies for Long Kui are extremely limited. The above interactions are inferred from the known pharmacological properties of its active constituents. Patients taking pharmaceutical medications should consult both their prescribing doctor and a qualified TCM practitioner before using this herb.

Dietary Advice

As Long Kui is a cold-natured herb used to clear Heat and toxins, avoid excessively cold or raw foods during the treatment period to protect the Stomach and Spleen. Light, easily digestible meals are recommended. Classical sources note that Long Kui should not be eaten together with green onions (cong) and Chinese chives (xie). When used fresh as food (cooked young shoots), it should always be thoroughly boiled first, and the cooking water discarded, to reduce glycoalkaloid content.

Cautions & Warnings

Although this herb is typically safe for most individuals, it may cause side effects in some people. Pregnant women, nursing mothers, postpartum women, and those with liver disease should use the formula with caution.

As with any Chinese herbal remedy, it is advisable to seek guidance from a qualified TCM practitioner before beginning treatment.