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Indigo is a flowering plant that has been used as a dye. The root has been used as an oil or cream to ease swelling from skin and joint problems like psoriasis. It can also be taken as a pill, powder, or extract. Indigo can also be made into a tea.
There are no advised doses for indigo.
Editorial process and description of evidence categories can be found at EBSCO NAT Editorial Process.
Certain species of indigo are not safe. Only use indigo that is from a reliable source. It is likely safe for most adults to use indigo on the skin. It may be safe to take indigo orally for a short time, but it may raise blood pressure. Not enough studies have been done to say whether it is safe to use for a long period.B1-B3
Talk to your doctor about any supplements or therapy you would like to use. Some can interfere with treatment or make conditions worse, such as:
A1. Deng S, May BH, et al. Plant extracts for the topical management of psoriasis: a systematic review and meta-analysis. Br J Dermatol. 2013 Oct;169(4):769-782.
A2. Lin YK, Chang YC, et al. A Chinese herb, indigo naturalis, extracted in oil (Lindioil) used topically to treat psoriatic nails: a randomized clinical trial. JAMA Dermatol. 2015 Jun;151(6):672-674.
A3. Farahnik B, Sharma D, et al. Topical botanical agents for the treatment of psoriasis: a systematic review. Am J Clin Dermatol. 2017 Aug;18(4):451-468.
A4. Cheng HM, Wu YC, et al. Clinical efficacy and IL-17 targeting mechanism of Indigo naturalis as a topical agent in moderate psoriasis. BMC Complement Altern Med. 2017 Sep 2;17(1):439.
B1. Matsuno Y, Hirano A, et al. Possible association of phlebitis-induced colitis with indigo naturalis. Gastroenterology. 2018 Aug;155(2):576-577.
B2. Nishio M, Hirooka K, et al. Pulmonary arterial hypertension associated with the chinese herb indigo naturalis for ulcerative colitis: it may be reversible. Gastroenterology. 2018 Aug;155(2):577-578.
B3. Kondo S, Araki T, et al. Colitis with wall thickening and edematous changes during oral administration of the powdered form of Qing-dai in patients with ulcerative colitis: a report of two cases. Clin J Gastroenterol. 2018 Aug;11(4):268-272.
C. Ulcerative Colitis
C1. Naganuma M, Sugimoto S, et al. Efficacy of indigo naturalis in a multicenter randomized controlled trial of patients with ulcerative colitis. Gastroenterology. 2018;154(4):935-947.
Last reviewed February 2020 by EBSCO NAT Review Board Eric Hurwitz, DC Last Updated: 5/27/2020