Most children and teenagers with obsessive-compulsive disorder improve with cognitive behavioural therapy (CBT) and SSRI medication, the standard first-line treatments. Some do not. A meaningful number respond only partly, leaving clinicians with few further options. A review examined what is known about N-acetylcysteine (NAC), an antioxidant supplement, as an add-on treatment for obsessive-compulsive and related disorders in children and adolescents aged 3 to 21.
The review drew on three randomised, placebo-controlled trials involving 121 young people, each running for 10 to 12 weeks. Two of the OCD trials found statistically significant improvement with NAC. Only one, though, showed a difference large enough to be clinically meaningful against placebo. A separate trial in trichotillomania, compulsive hair-pulling, found no benefit over placebo. Reported side effects were generally mild: nausea, blurred vision, fatigue, tremor and sweating. Doses of 2400 or 2700 mg a day, in divided doses, were the most studied.
The evidence here is limited and preliminary. Even so, it points to NAC as a possible augmentation option for children and adolescents with OCD who have not fully responded to CBT or SSRIs. Any decision to add a supplement like this should be made together with a treating doctor. If your child is struggling with OCD, speaking with a psychologist is a good place to start.
What the review looked at
Obsessive-compulsive and related disorders in children and adolescents cover OCD itself along with related conditions: trichotillomania (compulsive hair-pulling), excoriation (skin-picking) disorder, hoarding disorder and body dysmorphic disorder. Cognitive behavioural therapy and SSRIs are the established first-line treatments, but a substantial proportion of young people do not respond fully, or at all, to either.
This review searched PubMed, Ovid MEDLINE covering 1946 to July 2022, and the Cochrane Library, for English-language clinical trials and case studies of N-acetylcysteine (NAC) in patients aged 3 to 21 with a DSM-5 diagnosis in this group of disorders. NAC is an over-the-counter antioxidant supplement. It has been studied as a possible add-on treatment where standard options have not fully worked.
What it found
The review identified three randomised, double-blind, placebo-controlled trials, together involving 121 children and adolescents. Each measured symptom severity from baseline to 10 to 12 weeks of NAC therapy.
Two of the OCD trials found statistically significant improvement in symptoms with NAC compared with placebo. Only one of those two, however, showed a difference large enough to be considered clinically meaningful rather than simply statistically detectable, a distinction that matters because a statistically significant result can still be too small to notice in a person's day-to-day symptoms. A separate trial examining NAC specifically for trichotillomania found no difference between NAC and placebo.
Side effects reported across the trials were generally mild: nausea, blurred vision, fatigue, tremor and sweating. The most studied dosing regimen was either 2400 or 2700 mg a day, given in divided doses rather than all at once.
Why it matters for families
Many children and adolescents with OCD and related disorders do not achieve full symptom relief from CBT or SSRIs alone, and treating clinicians often have limited further options once those have been tried. This review suggests NAC augmentation may have a place for some of these young people, particularly where OCD itself has not responded adequately to first-line treatment. The picture for trichotillomania specifically was not supportive, so the same reasoning should not be assumed to apply there.
The limits of the evidence
The review's authors describe the evidence as preliminary. Three trials and 121 participants in total is a modest base from which to draw firm conclusions, and only one of the two positive OCD trials reached a clinically, rather than purely statistically, meaningful result. NAC is not proposed here as a replacement for CBT or SSRIs, but as a possible addition when those treatments have not been enough on their own.
If your child or teenager is affected by OCD, whether or not other treatments have already been tried, speaking with a psychologist is a sensible first step. A psychologist can properly assess what is happening for your child and, together with their GP or paediatrician, help work out whether additional options like this are worth discussing.