Obstructive sleep apnea syndrome (OSA) is the main manifestation of sleep-disordered breathing in children. Untreated OSA can lead to a variety of complications and adverse consequences mainly due to intermittent hypoxemia. The pathogenesis of OSA is multifactorial. In children aged 2 years or older, adenoid and/or tonsil hypertrophy are the most common causes of upper airway lumen reduction; obesity becomes a major risk factor in older children and adolescents since the presence of fat in the pharyngeal soft tissue reduces the caliber of the lumen. Treatment includes surgical and non-surgical options. This narrative review summarizes the evidence available on the first-line approach in children with OSA, including clinical indications for medical therapy, its effectiveness, and possible adverse effects. Literature analysis showed that AT is the first-line treatment in most patients with adenotonsillar hypertrophy associated with OSA but medical therapy in children over 2 years old with mild OSA is a valid option. In mild OSA, a 1- to 6-month trial with intranasal steroids (INS) alone or in combination with montelukast with an appropriate follow-up can be considered. Further studies are needed to develop an algorithm that permits the selection of children with OSA who would benefit from alternatives to surgery, to define the optimal bridge therapy before surgery, to evaluate the long-term effects of INS +/− montelukast, and to compare the impact of standardized approaches for weight loss.