Background Methods Allergen immunotherapy (AIT) is still the only causal treatment for allergic diseases. However, conventional subcutaneous immunotherapy (SCIT) administration schedules are time-consuming and patient nonadherence is a major barrier to achieving a satisfactory therapeutic effect. Our study aimed to analyze the causes leading to discontinuation of SCIT and to determine risk factors associated with nonadherence in respiratory allergies. This was a prospective study. Patients with respiratory allergies who had received standardized dust mite SCIT were enrolled from January 2012 to January 2014. And a follow-up study on these subjects was conducted via telephone interviews on an interval of 3 months and online communication through social network applications. Reasons for discontinuation were documented when patients claimed to stop treatment. Results Conclusion A total of 311 patients were enrolled in the study. The adherence rate at year 3 was 64.6%. Fifty-nine patients (19.0%) dropped out in year 1, 31 (10.0%) in year 2, and 20 (6.4%) in year 3. Reasons for nonadherence included inconvenience (32.7%), ineffectiveness (25.5%), improvement of symptoms (22.7%), and adverse reactions (14.5%). Children had higher adherence than adults (70.7% vs 55.0%) (p < 0.05). The dropout reasons were different among the children and adults groups (p < 0.005). The follow-up work was carefully and thoroughly done. All the 311 (100%) patients accepted the telephone interview, and 296 (95.2%) patients submitted questions and got rapid replies from doctors online. Adherence to SCIT was less than satisfactory in the real-life study. A close communication between doctors and patients is helpful in enhancing adherence with AIT in clinical practice.