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PubMed · Strobilanthes cusia (Nees) Kuntze, a multifunctional traditional Chinese medicinal plant, and its herbal medicines: A comprehensive review. (2021)
PubMed · Indigodole E from <i>Strobilanthes cusia</i> exhibits anti-IL-17A effect. (2022)
Reviewed by: HerbAlly Editorial Team, Medical herbalists and healthcare professionals
Indigo Naturalis contains active compounds including indirubin, tryptanthrin, and indigo that exert anti-inflammatory effects through multiple pathways. Indirubin, the primary active constituent, inhibits cyclin-dependent kinases and modulates inflammatory signaling pathways including NF-kappaB. Tryptanthrin demonstrates additional anti-inflammatory activity by inhibiting prostaglandin and leukotriene synthesis. These mechanisms contribute to its traditional use for inflammatory skin conditions and ulcerative colitis. Evidence Level: C.
Does Indigo Naturalis interact with any medications?
Limited data exists on specific drug interactions with Indigo Naturalis. Due to its anti-inflammatory properties and effects on inflammatory pathways, theoretical interactions may occur with immunosuppressive medications and anti-inflammatory drugs. Patients taking medications for autoimmune conditions should avoid this herb due to potential interference with treatment. Always consult a qualified healthcare provider before combining Indigo Naturalis with prescription medications. Evidence Level: C.
What is the recommended dosage for Indigo Naturalis?
For inflammatory bowel disease, the typical adult dosage is 1.5 to 3 grams of processed powder taken three times daily. For inflammatory skin conditions, Indigo Naturalis is typically applied topically as a prepared formulation. Dosage should be individualized based on the specific condition and under guidance from a qualified practitioner. Avoid prolonged high-dose use due to pulmonary hypertension risk. Evidence Level: C.
Is Indigo Naturalis safe during pregnancy?
Indigo Naturalis is contraindicated during pregnancy and should be strictly avoided. The herb has been associated with adverse effects that could harm fetal development. Women who are pregnant, attempting to conceive, or breastfeeding should not use this herb in any form. Consult a qualified healthcare provider for safe alternatives for inflammatory conditions during pregnancy. Evidence Level: C.
What are the side effects of Indigo Naturalis?
Common side effects include gastrointestinal upset and blue discoloration of stool, which is harmless and results from the indigo pigment. A serious concern with prolonged high-dose use is pulmonary arterial hypertension, a potentially dangerous condition affecting lung blood vessels. Patients with pre-existing pulmonary hypertension or autoimmune conditions should avoid this herb. Discontinue use if shortness of breath develops. Evidence Level: C.
What is Indigo Naturalis used for in traditional medicine?
Indigo Naturalis has been used in traditional Chinese medicine for inflammatory skin conditions, oral mucosal conditions, and liver heat patterns. In Asian medicine, it is employed as an anti-inflammatory agent for inflammatory bowel disease, with indirubin showing particular promise for ulcerative colitis. The processed leaves yield the characteristic indigo dye used medicinally. Evidence Level: C.
PubMed-compiled information sheet
This sheet was compiled from PubMed (NIH) abstracts using AI assistance. Every factual claim is cited to a real PubMed article (see the source list). It has not yet been human-reviewed — confirm with a healthcare provider before use.
Compiled from 30 PubMed articles · model: gemma4:31b
Summary
Indigo naturalis (Qing dai) is a traditional herbal medicine derived from plants such as Strobilanthes cusia, used primarily for autoimmune conditions like psoriasis and ulcerative colitis [PMID:38301993].
Background
Indigo naturalis is a dried powder derived from plants including Baphicacanthus cusia (Strobilanthes cusia), Polygonum tinctorium Ait., and Isatis indigotica Fork [PMID:38301993]. It is a processed product of S. cusia, a traditional Chinese medicinal plant [PMID:32889034].
Traditional uses
Historically used as a dye in ancient India, Egypt, Africa, and China [PMID:38301993]. In traditional medicine, it has been used for hemoptysis, epistaxis, chest discomfort, aphtha [PMID:38301993], and for clearing heat, detoxifying blood, eliminating spots, and reducing fire [PMID:35872288].
Active compounds
Main active components include indigo, indirubin, tryptanthrin [PMID:39316667, PMID:38948310], and isatin [PMID:38948310]. Other isolated compounds include indazole alkaloids such as indigodoles A, C, and E [PMID:35192387, PMID:30852259].
Mechanism of action
In psoriasis, it regulates keratinocyte proliferation and differentiation, restores epidermal barrier function, and reduces inflammatory processes [PMID:26954317]. Specific compounds like indigodole E, indigodole C, and tryptanthrin inhibit IL-17A protein production or gene expression [PMID:35192387, PMID:30852259]. In inflammatory bowel disease (IBD), mechanisms include activation of the Aryl hydrocarbon Receptor (AhR) pathway, inhibition of the NF-κB/NLRP3/IL-1β pathway, and modulation of the TLR4/MYD88/NF-κB pathway [PMID:38948310]. Indirubin may exert effects via PI3K/AKT/mTOR, MAPK, and JAK/STAT3 pathways [PMID:35598366].
Clinical evidence
Evidence AUlcerative Colitis
Pooled clinical response rate was 0.796 and clinical remission rate was 0.668; clinical response rates were significantly higher compared to placebo (RR 3.70) [PMID:38006941, PMID:38612967].
Evidence CPsoriasis
Chinese herbal medicine formula groups showed a higher response rate for PASI60 compared to control groups [PMID:39316667].
Evidence DPediatric Ulcerative Colitis
In a survey of 107 patients, 80.2% achieved clinical remission within 6 months [PMID:35831249].
Evidence CAcute Promyelocytic Leukemia (APL)
Oral Realgar-Indigo Naturalis formula (RIF) plus all-trans-retinoic acid (ATRA) displays high efficacy and allows for home-based postremission therapy [PMID:33614484].
Safety & adverse effects
Long-term consumption is associated with adverse effects [PMID:38301993]. Reported severe complications include indigo naturalis-induced colitis [PMID:29964335, PMID:31034341] and pulmonary arterial hypertension (PAH) [PMID:41403416, PMID:31034341]. Indirubin has been linked to hepatic injury in mice with chronic colitis, mediated by macrophage transport of insoluble aggregates to the liver [PMID:40546113].
Evidence summary
Strong evidence (Meta-analyses) supports efficacy for ulcerative colitis. Evidence for psoriasis and leukemia is primarily based on reviews and smaller studies. Significant safety concerns exist regarding long-term use, specifically PAH and colitis.
PubMed sources
1.PMID: 40210174 (2025) — Herbal medicine for treating psoriasis: A systematic review. · Complementary therapies in medicine
2.PMID: 29964335 (2018) — Indigo naturalis-induced colitis. · Digestive endoscopy : official journal of the Japan Gastroenterological Endoscopy Society
3.PMID: 38006941 (2024) — Indigo naturalis (Qing dai) for inflammatory bowel disease: A systematic review and meta-analysis. · Clinics and research in hepatology and gastroenterology
4.PMID: 35872288 (2022) — Psoriasis treatment using Indigo Naturalis: Progress and strategy. · Journal of ethnopharmacology
5.PMID: 35192387 (2022) — Indigodole E from Strobilanthes cusia exhibits anti-IL-17A effect. · Natural product research
Government sources
No direct government monograph is available for this herb. The content below is AI-generated and has not been verified against an authoritative government source. Use the search links to check official sources before relying on this information.
PMID: 38301993 (2024) — The double-edged sword effect of indigo naturalis. · Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association
7.PMID: 41403416 (2025) — Long-term outcomes of Qing-Dai-induced pulmonary arterial hypertension. · ERJ open research
9.PMID: 33614484 (2020) — Oral Realgar-Indigo Naturalis Formula Plus Retinoic Acid for Acute Promyelocytic Leukemia. · Frontiers in oncology
10.PMID: 15612772 (2004) — Formation of natural indigo derived from woad (Isatis tinctoria L.) in relation to product purity. · Journal of agricultural and food chemistry
11.PMID: 26954317 (2016) — A Review of Indigo Naturalis as an Alternative Treatment for Nail Psoriasis. · Journal of drugs in dermatology : JDD
12.PMID: 38948310 (2024) — Indigo Naturalis in Inflammatory Bowel Disease: mechanisms of action and insights from clinical trials. · Journal of pharmacopuncture
13.PMID: 37904107 (2023) — Identification of novel flavin-dependent monooxygenase from Strobilanthes Cusia reveals molecular basis of indoles' biosynthetic logic. · BMC plant biology
14.PMID: 32889034 (2021) — Strobilanthes cusia (Nees) Kuntze, a multifunctional traditional Chinese medicinal plant, and its herbal medicines: A comprehensive review. · Journal of ethnopharmacology
15.PMID: 33317592 (2020) — From natural dye to herbal medicine: a systematic review of chemical constituents, pharmacological effects and clinical applications of indigo naturalis. · Chinese medicine
16.PMID: 31034341 (2019) — Treatment with indigo naturalis for inflammatory bowel disease and other immune diseases. · Immunological medicine
17.PMID: 35831249 (2022) — Qing-Dai for pediatric ulcerative colitis multicenter survey and systematic review. · Pediatrics international : official journal of the Japan Pediatric Society
18.PMID: 37669429 (2023) — High-Quality Indigo Naturalis Obtained with Automatic Foam Separation. · ACS applied materials & interfaces
19.PMID: 32981147 (2020) — Blue genome: chromosome-scale genome reveals the evolutionary and molecular basis of indigo biosynthesis in Strobilanthes cusia. · The Plant journal : for cell and molecular biology
20.PMID: 39316667 (2024) — Evidence and potential mechanism of action of indigo naturalis and its active components in the treatment of psoriasis. · Annals of medicine
21.PMID: 39154058 (2024) — Complementary and Alternative Therapies for Psoriasis. · Archives of dermatological research
22.PMID: 40756994 (2025) — Indigo naturalis for inflammatory bowel disease: evidence from animal studies and molecular mechanisms. · Frontiers in pharmacology
23.PMID: 40546113 (2025) — Macrophage-Mediated Transport of Insoluble Indirubin Induces Hepatic Injury During Intestinal Inflammation. · Advanced science (Weinheim, Baden-Wurttemberg, Germany)
24.PMID: 38612967 (2024) — Herbal Medicines for the Treatment of Active Ulcerative Colitis: A Systematic Review and Meta-Analysis. · Nutrients
25.PMID: 35598366 (2022) — Pharmacological properties of indirubin and its derivatives. · Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie
26.PMID: 32237505 (2020) — [Advances in biosynthesis of indigo in plants]. · Zhongguo Zhong yao za zhi = Zhongguo zhongyao zazhi = China journal of Chinese materia medica
27.PMID: 30852259 (2019) — Indole alkaloids indigodoles A-C from aerial parts of Strobilanthes cusia in the traditional Chinese medicine Qing Dai have anti-IL-17 properties. · Phytochemistry
28.PMID: 36046107 (2022) — The complete chloroplast genome of Strobilanthes crispus (Acanthaceae). · Mitochondrial DNA. Part B, Resources
29.PMID: 37773314 (2024) — Phytochemical and Pharmacological Properties of a Traditional Herb, Strobilanthes Cusia (Nees) Kuntze. · Molecular biotechnology
30.PMID: 36678602 (2023) — Combining the In Silico and In Vitro Assays to Identify Strobilanthes cusia Kuntze Bioactives against Penicillin-Resistant Streptococcus pneumoniae. · Pharmaceuticals (Basel, Switzerland)