Introduction N-acetylcystein (NAC), a precursor to the amino acid cysteine, has been emerging as an interesting add-on treatment in several psychiatric conditions and especially in Obsessive Compulsive Disorder (OCD). These results may be linked to its metabolic profile: antioxidant properties through glutathione production; anti-inflammatory properties; and modulation of the glutamatergic and dopaminergic systems of neurotransmission.

Objectives Review the potential therapeutic effects of NAC in psychiatry, with main focus on syndromes of the obsessive-impulsive spectrum with report of a clinical case.

Methods Case report of a patient with OCD and Hoarding disorder, with complete clinical remission after treatment with NAC; bibliographic search using PubMed/MedLine database with the following keywords: n-acetylcysteine; OCD; hoarding.

Results We report and discuss the case of a 44-year-old man with a diagnosis of Obsessive Compulsive Disorder with orderliness and contamination themes, coupled with Hoarding disorder. The patient experienced gradual though slight improvement with Paroxetine (60 mg/day) to which was subsequently added Risperidone (2 mg/day) with further slight improvement. In combination with the previously given pharmacological agents, NAC (1800 mg/day) was introduced with subsequent complete remission of all symptoms.