Treatment-Resistant OCD: Can NAC Help?

A 36 year-old-female with history of Obsessive-Compulsive Disorder (OCD) is currently on fluvoxamine 300 mg/day with clomipramine 250 mg/day with persistence of intrusive obsessive thoughts resulting in compulsive behaviors of frequent hand washing.

OCD can be a disabling condition in some cases, where first line intervention including CBT (cognitive behavioral therapy) and serotonergic antidepressants are not helpful.

Treatment Resistant OCD is defined as patients who have undergone an adequate trial of SRI (clomipramine or SSRI) and do not respond or show unsatisfactory results. Since treatment resistant OCD can account for 40-50% of OCD patients, this is a clinically relevant topic for psychiatry practitioners. 

Let’s Answer this Question:

N-acetyl cysteine (NAC) have demonstrated positive results in reducing the severity of symptoms in patients with Obsessive-Compulsive and Related Disorders. What dose and duration of NAC is adequate for exerting an initial therapeutic effect?

Answer: (d) Dose of 2,400- 3,000 mg/day for a minimum of 12 weeks. 

  1. Clin Psychopharmacol Neurosci. 2015 Apr; 13(1): 12–24.
  2. JAMA Psychiatry. 2016 May 1;73(5):490-6.
  3. J Clin Psychopharmacol. 2012 Dec; 32(6):797-803. (pubmed)

N-acetylcysteine (NAC) is a glutamate-modulating agent, which have shown efficacy in patients with treatment-refractory obsessive-compulsive disorder as an adjunct to serotonin reuptake inhibitor treatment.

Read our course chapter to learn the following clinical details regarding N-Acetyl Cysteine (NAC):

  1. Mechanism of action for NAC in Obsessive Compulsive and Related Disorders.
  2. What dose of N-Acetyl Cysteine and for how long?
  3. How to titrate N-Acetyl Cysteine dosing?
  4. Common Adverse Effects of N-Acetyl Cysteine.
  5. Do these adverse events improve with continuation of NAC?



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