N-acetylcysteine in paediatrics: a review of efficacy, safety and dosing strategies in respiratory care.

N-acetylcysteine (NAC) is widely used for its mucolytic, antioxidant, anti-inflammatory and synergistic antibacterial properties in the treatment of respiratory diseases. NAC and other mucolytics and mucoactive medications are frequently employed in the adult population and in paediatric settings to improve mucus clearance in conditions such as cystic fibrosis, bronchiolitis, pneumonia, and both chronic and acute bronchitis, with varying degrees of success. This narrative review evaluates the efficacy and safety of NAC in paediatric acute and chronic respiratory diseases, synthesizing data from clinical trials, observational studies and real-world evidence, with a particular focus on optimizing dosing based on patient-specific characteristics. Numerous studies indicate that oral NAC doses of 20 mg/kg/day for acute conditions and 200 mg three times daily for chronic conditions are generally effective and well tolerated in children. However, most participants in these studies were older than 9 years, resulting in a lack of literature-based evidence for the optimal dosing in younger children over 2 years of age. Given the significant weight variations within this age group, weight-based dosing is recommended to ensure appropriate drug exposure and optimize treatment benefits. Weight-based dosing adjustments and patient monitoring may help optimize treatment outcomes and reinforce the overall positive safety and tolerability profile in paediatric settings. NAC is a valuable therapeutic agent for paediatric respiratory diseases, particularly in older children. In younger patients, weight-adjusted dosing and careful monitoring for potential adverse effects may help maximize efficacy and maintain its favourable tolerability profile.