Table 3.
Summarizes all NAC treatment studies for onychophagia, which includes one pediatric randomized double-blind controlled trials and three case reports.
| Summary of NAC Treatment Studies in Onychophagia | |||||||
|---|---|---|---|---|---|---|---|
| Study | Design | Patients | Age (Year) | Comorbidities | NAC Dose | Other Concurrent Medications | Outcomes |
| Ghanizadeh et al. (2013) [58] | RDBPCT | Pediatric (n = 42) | 6–18 | OCD, depression, anxiety, ADHD, tic disorder, SPD | 200–800 mg/day | SSRIs, SNRIs, stimulants, antipsychotics, TCAs | Significantly increased nail length in treatment group compared to placebo after 1 month (p < 0.04). No significant difference noted after 2 months. |
| Kilic and Keles (2019) [35] | Case report | Adult (n = 1) | 24, M | Not specified | 1200–1800 mg/day | None | After 3 weeks on 1800 mg/day, patient lost urge to bite his nails. Efficacy was maintained after 6 weeks. |
| Ghanizadeh and Derakhshan (2012) [59] | Case report | Pediatric (n = 1) | 8, M | Autism | 800 mg/day | Risperidone 2 mg/day and thioridazine 10 mg/day | After 1 month of NAC, patient’s parents reported reduced nail biting and autism symptoms. |
| Berk et al. (2009) [60] | Case report | Adult (n = 3) | 46, F; 44, F; 46, M | Bipolar disorder; Depression, anxiety, bipolar disorder; Depression, bipolar disorder | 2000 mg/day; 2000 mg/day; Not specified | Lithium 900 mg/day, quetiapine 300 mg/day; Mirtazapine 15 mg; None | Case 1: After 2 weeks, patient completely stopped nail biting and results were maintained at 7-month follow-up; Case 2: After 4 months, patient completed stopped nail biting and results were maintained at 2-month follow-up; Case 3: After 28 weeks, patient reported reduction in nail biting. |
NAC, N-acetylcysteine; RDBPCT, randomized double blind placebo controlled trial; ADHD, attention deficit hyperactive disorder; OCD, obsessive-compulsive disorder; SPD, skin picking disorder; TTM, trichotillomania; PTSD, post-traumatic stress disorder; BED, binge eating disorder; SSRIs, selective serotonin reuptake inhibitors; SNRIs, serotonin-norepinephrine reuptake inhibitors; TCAs, tricyclic antidepressants; MGH-HPS, Massachusetts General Hospital-Hair Pulling Scale; NE-YBOCS, Yale-Brown Obsessive Compulsive Scale; CGI, Clinical Global Impression.