N-acetylcysteine (NAC) — modern psychiatric group

Summary for N-acetylcysteine (NAC)

August 8th, 2026
NAC is a potentially useful over-the-counter supplement aimed towards adjunctive treatment for OCD and skin/hair-picking disorders. NAC works by reducing antioxidants and inflammation within the human body. Please note that NAC is not a replacement for the standard of care (eg, antidepressants [SSRI/SNRI] + CBT [Cognitive Behavioral Therapy] vs HRT [Habit-Reversal Training]) but rather as an off-label, adjunctive treatment within the category of Complementary and Alternative Medications (CAM).

If you’d like to purchase N-acetylcysteine, you can visit our Amazon affiliate link below.
Please note that proceeds from qualified purchases will go towards to our Amazon Associate account which in turn helps to keep our website going.
Thank you!

AFFILIATE LINK (N-acetylcysteine)

What is NAC?

N-acetylcysteine (NAC) is a derivative of the amino acid L-cysteine and glutathione (GSH), both of which act as natural antioxidants with anti-inflammatory properties within the human body. NAC is included on the WHO List of Essential Medicines and has been in clinical use since the 1960s. NAC is readily available as an over-the-counter (OTC) medication that can be utilized as an adjunctive treatment for the use towards impulse-control disorders, obsessive-compulsive disorder (OCD), and obsessive-compulsive related disorders (eg, trichotillomania aka skin-picking disorder and/or hair-pulling disorder). The proposed mechanism of action for NAC on how it works for mental health is thought to be due to glutamate modulation (wherein it activates cystine-glutamate antiporter to restore extracellular glutamate homeostasis) as well as anti-inflammatory effects (via inhibition of NF-κB activation thereby reducing inflammatory agents such as IL-6, IL-1β, and TNF-α production). Of note, NAC also acts as a direct antioxidant which scavenges reactive oxygen/nitrogen in the body as a derivative of L-cysteine and glutathione (GSH).

What does the evidence show for NAC?

For trichotillomania / excoriation disorder (aka skin/hair-picking disorder)
For the use of NAC trichotillomania / excoriation disorder (aka skin-picking disorder), NAC has has moderate-certainty evidence supporting efficacy for trichotillomania (TTM) in adults, and is one of only three interventions with both replicated evidence and strong effect sizes for TTM, alongside habit reversal therapy and ACT-enhanced habit reversal.

In adults, a key Randomized Clinical Trial [RCT] (Grant 2009) revealed that:

NAC 1200 mg twice daily was associated with a 3.5-fold greater likelihood of treatment response vs placebo (RR 3.50, 95% CI 1.34–9.17; NNT = 2.5; n=50; moderate-certainty evidence).
Significant reductions on the MGH Hair Pulling Scale (MD −5.60, 95% CI −8.50 to −2.70) and CGI-S (MD −1.24, 95% CI −1.93 to −0.55).
56% of NAC-treated patients achieved "much improved" or "very much improved" status by study endpoint, compared to ~16% on placebo.
Treatment effects were first noted at 9 weeks.

For OCD (aka obsessive-compulsive disorder)
For the use of NAC in OCD, NAC appears to separate from placebo around weeks 5–12, though importantly the largest trial found no benefit at any time point.
Timeline from available trials:

Meta-analysis (6 RCTs): The only time window showing a borderline benefit was 5–8 weeks (p=0.05); no difference was seen at <5 weeks or >12 weeks.
Pediatric pilot (n=11): Effects began separating from placebo at week 8, with meaningful CY-BOCS reduction by week 12.
Adult 16-week RCT (n=44): A significant reduction in the compulsions subscale was observed at week 12, but this dissipated by week 16; overall Y-BOCS was not significant.
Pediatric trial (n=34): Improvement in resistance/control to compulsions was detected after 10 weeks of NAC (up to 2,400 mg/day).

What dose of NAC should I take?

For trichotillomania / excoriation disorder (aka skin/hair-picking disorder)
If a trial of NAC is utilized for skin/hair-picking disorder in adults, a reasonable approach based on available data would be to assess response at 6–8 weeks at doses of up to 600-1200mg twice daily and to discontinue if no improvement is observed.

For OCD (aka obsessive-compulsive disorder)
If a trial of NAC is utilized for OCD is undertaken, a reasonable approach based on available data would be to assess response at 8–12 weeks at doses of up to 2,400–3,000 mg/day, and discontinue if no improvement is observed.

Where can I purchase NAC?

If you’d like to purchase N-acetylcysteine, you can visit our Amazon affiliate link below.
Please note that proceeds from qualified purchases will go towards to our Amazon Associate account which in turn helps to keep our website ongoing.
Thank you!