A target-trial emulation study using data from 2,713 patients with allergic respiratory disease found that starting sublingual immunotherapy was associated with reduced disease worsening and higher remission rates over 36 months. The analysis also supports a longer-duration view of effectiveness rather than short follow-up windows. The study design used emulation methods to better approximate randomized evidence and evaluated outcomes across a multi-year horizon. The finding aligns with demand for treatments that can change the disease course, not only symptom control. For allergy and respiratory care teams, the practical question remains how to select patients for long-term immunotherapy while balancing safety, adherence, and persistence of response.