Early-life exposure to antibiotics has been increasingly associated with disruptions in gut microbiota, potentially influencing immune and metabolic development. Epidemiological and experimental studies suggest that antibiotic use in infancy may heighten the risk of atopic conditions such as asthma, eczema, and allergic rhinitis, as well as metabolic disorders including obesity and insulin resistance. The critical window of immune programming during infancy underscores the importance of judicious antibiotic prescribing. Understanding the underlying mechanisms, such as microbial dysbiosis, altered short-chain fatty acid production, and immune modulation, can help inform preventive strategies and promote long-term health outcomes in paediatric populations.