The most appropriate treatment is the combination of a low-dose inhaled glucocorticoid and long-acting β₂-agonist (LABA) in addition to an as-needed short-acting β₂-agonist. Appropriate initial classification of asthma is important in guiding the strength and type of therapy that is likely to be most effective. Underestimating asthma severity may delay resolution of symptoms and may inadequately manage airway inflammation. This patient has newly diagnosed moderate persistent asthma based on her daily symptoms and spirometry showing an FEV₁ of greater than or equal to 60% but less than 80% of predicted that responds to bronchodilator therapy. The preferred regimen for treating moderate persistent asthma is the combination of a low-dose inhaled glucocorticoid and LABA. Adding a LABA to inhaled glucocorticoid therapy has increased synergistic anti-inflammatory properties compared with either agent alone. Additionally, recent data have demonstrated that long-acting anticholinergic therapy may be appropriate as step-up therapy if moderate persistent asthma does not resolve with combination inhaled glucocorticoid and LABA therapy.

A leukotriene agonist or low-dose inhaled glucocorticoid are recommended treatment options for patients with mild persistent asthma, defined as asthma symptoms occurring more than 2 days per week but not daily with an FEV₁ of greater than or equal to 80% of predicted. The addition of either therapy alone may not adequately treat the degree of asthma seen in this patient.

This patient requires anti-inflammatory controller therapy. Recommending daily use of her oral antihistamine would not address her lower airway inflammation and would not be an appropriate intervention to control her asthma symptoms.