N-acetylcysteine augmentation therapy for moderate-to-severe obsessive-compulsive disorder: randomized, double-blind, placebo-controlled trial

J Clin Pharm Ther. 2016 Apr;41(2):214-9. doi: 10.1111/jcpt.12370. Epub 2016 Mar 2.


What is known and objective: N-acetylcysteine (NAC) has been proposed as a potential therapy for obsessive-compulsive disorder (OCD) as it may regulate the exchange of glutamate and prevent its pre-oxidant effects. The aim of the present double-blind, placebo-controlled trial was to assess the efficacy and tolerability of NAC augmentation in moderate-to-severe (OCD) treatment.

Methods: In this randomized, double-blind, two-centre, placebo-controlled, 10-week trial, patients with moderate-to-severe OCD were enrolled. Patients were randomized into two parallel groups to receive fluvoxamine (200 mg daily) plus placebo or fluvoxamine (200 mg daily) plus NAC (2000 mg daily). A total of 44 patients (22 in each group) were visited to evaluate response to therapy using the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) at baseline, and at weeks 4, 8 and 10. Side effects were recorded using predesigned checklists upon each visit.

Results and discussion: Repeated-measures ANOVA showed a significant effect for time × treatment interaction (Greenhouse-Geisser corrected: F = 5·14, d.f. = 1·64, P = 0·012) in the Y-BOCS total score and a significant effect for time × treatment interaction (Greenhouse-Geisser corrected: F = 5·44, d.f. = 1·54, P = 0·011) in the Y-BOCS obsession subscale between the two groups.

What is new and conclusion: Our results showed that NAC might be effective as an augmentative agent in the treatment of moderate-to-severe OCD.

Trial registration: Iranian Registry of Clinical Trials (www.irct.ir): IRCT201405271556N60.

Keywords: N-acetylcysteine; augmentative therapy; obsessive-compulsive disorder; randomized controlled trial.

Publication types

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

MeSH terms

  • Acetylcysteine / therapeutic use*
  • Adult
  • Double-Blind Method
  • Drug Interactions
  • Drug Therapy, Combination / methods
  • Female
  • Fluvoxamine / therapeutic use
  • Humans
  • Iran
  • Male
  • Obsessive-Compulsive Disorder / drug therapy*
  • Psychiatric Status Rating Scales
  • Selective Serotonin Reuptake Inhibitors / therapeutic use
  • Treatment Outcome


  • Serotonin Uptake Inhibitors
  • Fluvoxamine
  • Acetylcysteine

Associated data

  • IRCT/201405271556N60