Efficacy and safety of Indigo naturalis extract in oil (Lindioil) in treating nail psoriasis: a randomized, observer-blind, vehicle-controlled trial

Phytomedicine. 2014 Jun 15;21(7):1015-20. doi: 10.1016/j.phymed.2014.02.013. Epub 2014 Mar 26.


Treating nail psoriasis is notoriously difficult and lacks standardized therapeutic regimens. Indigo naturalis has been demonstrated to be safe and effective in treating skin psoriasis. This trial was conducted to evaluate the efficacy and safety of refined indigo naturalis extract in oil (Lindioil) in treating nail psoriasis. Thirty-one outpatients with symmetrically comparable psoriatic nails were enrolled. Lindioil (experimental group) or olive oil (control group) was applied topically to the same subjects' two bilaterally symmetrical psoriatic nails twice daily for the first 12 weeks and then subjects applied Lindioil to both hands for 12 additional weeks. Outcomes were measured using Nail Psoriasis Severity Index (NAPSI) for five nails on one hand and for the single most severely affected nail from either hand. The results show a reduction of NAPSI scores for the 12-week treatment for the Lindioil group (49.8% for one hand and 59.3% for single nail) was superior to the reduction in the scores for the control group (22.9%, 16.3%, respectively). There were no adverse events during the 24 weeks of treatment. This trial demonstrates that Lindioil is a novel, safe and effective therapy for treating nail psoriasis.

Keywords: Indigo naturalis; Indirubin; Nail psoriasis; Psoriasis; Traditional Chinese medicine.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acanthaceae / chemistry
  • Adult
  • Aged
  • Chromatography, High Pressure Liquid
  • Drugs, Chinese Herbal / analysis
  • Drugs, Chinese Herbal / chemistry
  • Drugs, Chinese Herbal / therapeutic use*
  • Female
  • Humans
  • Male
  • Medicine, Chinese Traditional
  • Middle Aged
  • Nail Diseases / drug therapy*
  • Nail Diseases / pathology
  • Nails / drug effects
  • Nails / pathology
  • Plants, Medicinal / chemistry
  • Psoriasis / drug therapy*
  • Psoriasis / pathology
  • Treatment Outcome
  • Young Adult


  • Drugs, Chinese Herbal
  • Qingdai compound