N-acetylcysteine: reinventing classic pharmacology through skin

N-acetylcysteine (NAC), traditionally known for its mucolytic properties and as an antidote for acetaminophen poisoning, has emerged as a multifunctional molecule with growing interest in dermatology. Its pleiotropic mechanisms -including modulation of redox balance, disulfide bond disruption, replenishment of intracellular glutathione, and regulation of inflammatory, microbial, and epigenetic pathways- have opened avenues for its therapeutic repurposing in cutaneous medicine. In congenital ichthyoses, topical NAC formulations have shown promising results, improving scaling and barrier function. NAC has also demonstrated efficacy in psychodermatological conditions such as trichotillomania and excoriation disorder, likely through glutamatergic modulation. In acne vulgaris and wound healing, its antioxidant and anti-inflammatory actions appear beneficial, with early data supporting its role as an adjunctive treatment. Moreover, its use in preventing UV-induced photodamage and improving dermal matrix remodelling further highlights its potential in both therapeutic and preventive dermatology. Although findings are encouraging, most studies remain limited in scale and methodological rigor. NAC represents a paradigmatic case of drug repurposing with a solid biochemical rationale, offering a versatile and low-cost option that may complement conventional dermatological therapies across multiple disease spectrums. Larger randomized controlled trials are needed to confirm its clinical utility.