N-Acetylcysteine Promising for Psychodermatologic Disorders

trichotillomania girl pulling hair
trichotillomania girl pulling hair
Treatment outcomes of N-acetylcysteine (NAC) for trichotillomania, skin-picking disorder, and onychophagia are reviewed.

N-acetylcysteine (NAC) treatment was safe and effective for patients with trichotillomania (TTM), skin-picking disorder (SPD), and onychophagia, a letter to the editor published in the Journal of The European Academy of Dermatology and Venerology noted.

Investigators at the University of British Columbia in Canada searched publication databases through March 2022 investigating NAC treatment for psychodermatologic disorders. A total of 19 studies were included in this systematic review and meta-analysis.

The study population comprised 126 patients mean age 26 (range, 4-65) years, 81% were girls or women, and 3 patients had concomitant conditions. The patients had TTM (n=60), SPD (n=43), and onychophagia (n=26).

The patients received 600 to 3000 mg NAC daily for 0.5 to 10 months.

Among the TTM cohort, 58% of patients were responders. Stratified by age, the response rate was higher among the adults (70%) than the children (40%). The average response time was 2.1 (range, 0.5-6) months and 25% had a recurrence. A fifth (20%) of patients experienced an adverse event of nausea (50%), difficulty swallowing medication (17%), diarrhea (8%), rash (8%), mild flatulence (8%), and depression (8%). Treatment was not completed by 12% due to poor adherence (67%), change in concomitant medication (33%), and adverse events (17%).

For the SPD group, the response rate was 58% among the 40 adult patients. The mean duration of response was 2.9 (range, 1-6) months and 75% had a recurrence. This group had a similar adverse event rate (21%) with events of nausea (56%), constipation (22%), dizziness (11%), and dry mouth (11%). A total of three patients were lost to follow-up.

In the onychophagia cohort, the response rate was 100% among both the children and adults. The average duration of response was 1.4 (range, 0.5-7) months and 25% had a recurrence. Fewer in this group reported adverse events (8%) of headache (33%), severe aggression (33%), and mild flatulence (33%). Over a quarter of patients (26%) did not complete treatment due to medication refusal (43%), adverse events (29%), and loss to follow-up (29%).

The major limitations of this analysis were the small sample sizes and differing NAC treatment regimens.

These data indicated to the researchers that NAC may be a safe and effective treatment for patients with psychodermatologic disorders. The investigators suggest “comprehensive investigation into the neurobiology and pathophysiology of these conditions, as well as pharmacokinetics of NAC, for a better understanding of therapeutic indications.”

Disclosure: Multiple authors declared affiliations with industry. Please refer to the original article for a full list of disclosures.


Kashetsky N, Wong A, Lam JM, Wong SM, Mukovozov I. Efficacy of N-acetylcysteine (NAC) in trichotillomania (hair-pulling disorder), skin-picking disorder and onychophagia (compulsive nail-biting). E J Acad Dermatol Venerol. Published online August 14, 2022. doi:10.1111/jdv.18508