Sublingual immunotherapy (SLIT) permits rapid antigen escalation with an improved safety profile over that of subcutaneous immunotherapy. Outcomes for SLIT in terms of the timing of clinical improvement were investigated in a retrospective review of patients undergoing SLIT who completed quality of life (QOL) and medication-use questionnaires at baseline and immediately after antigen escalation was performed. A subset of patients (n = 24) also completed maintenance-phase questionnaires. Paired post-escalation data (mean 5.5 weeks; N = 38) demonstrated improvement (p< 0.05) in overall QOL scores and in 6 of 14 symptom domains. Maintenance phase data (n = 24) revealed significant improvements in total QOL scores and in 5 symptom domains. A significant reduction in nasal steroid use was also demonstrated during the maintenance phase of treatment (p < 0.05). Significant improvement is seen immediately post-escalation in SLIT patients. This improved QOL appears to be maintained, and perhaps even increases, during the maintenance phase, with decreased nasal steroid use.