The SYGMA (Symbicort Given as Needed in Mild Asthma) studies evaluated the efficacy and safety of as-needed budesonide (BUD)-formoterol (FORM) in patients whose asthma was uncontrolled on as-needed inhaled short-acting bronchodilators (subgroup 1) or controlled on inhaled corticosteroids (ICS) or leukotriene receptor antagonists (subgroup 2). To assess the influence of prestudy treatment in a analysis of the SYGMA studies. In the SYGMA 1 (NCT022149199) and SYGMA 2 (NCT02224157) 52-week, double-blind, randomized, parallel-group studies, 6,735 patients with mild asthma were randomized to as-needed BUD-FORM, low-dose BUD + as-needed terbutaline (BUD maintenance), or as-needed terbutaline (SYGMA 1 only). Exacerbation rates and changes in symptom control and lung function were compared among treatments for both subgroups. In a pooled analysis of SYGMA 1 and 2, the annual severe exacerbation rate in subgroup 1 was significantly lower with as-needed BUD-FORM (0.08 [95% confidence interval (CI), 0.06-0.10]) than with BUD maintenance (0.10 [95% CI, 0.09-0.13]) (rate ratio [RR], 0.74 [95% CI, 0.56-0.98];  = 0.03), and similar results were shown in subgroup 2 with BUD-FORM (0.12 [95% CI, 0.10-0.14]) and BUD maintenance (0.10 [95% CI, 0.09-0.13]) (RR, 1.10 [95% CI, 0.86-1.41];  = 0.44). In SYGMA 1, the annual severe exacerbation rate in both subgroups was significantly lower with as-needed BUD-FORM than with as-needed terbutaline (subgroup 1: RR, 0.34 [95% CI, 0.20-0.58];  < 0.001; subgroup 2: RR, 0.37 [95% CI, 0.25-0.54];  < 0.001). The number needed to treat to prevent one severe exacerbation with as-needed BUD-FORM and BUD maintenance versus as-needed terbutaline were 20 and 34 in subgroup 1 and 13 and 12 in subgroup 2, respectively. These findings suggest that, for patients with mild asthma currently receiving short-acting β-agonists alone, as-needed low-dose ICS-FORM should be preferred over maintenance ICS as initial controller treatment. For patients whose asthma is controlled on maintenance low-dose ICS, as-needed BUD-FORM is an alternative to maintenance ICS without the need for daily treatment, and both of these options are safer than switching to short-acting β-agonist-only treatment.