Objective This study was conducted to investigate whether the add-on treatment of allergic rhinitis (AR) based on the Self-assessment of Allergic Rhinitis and Asthma (SACRA) questionnaire for assessing AR control improves both AR and asthma control in asthmatic patients with AR. Methods This multi-center prospective study was performed in Nagano prefecture, Japan. Two hundred five asthmatic patients and 23 respiratory physicians participated in the study. We administered add-on AR treatments based on the results of the SACRA questionnaire. After the first SACRA questionnaire, 67 asthmatic patients agreed to receive an add-on AR treatment. Three months after the AR treatment, a secondary SACRA questionnaire, asthma control test (ACT), and pulmonary function tests were performed. Results After the add-on AR treatment, the visual analogue scales (VASs) for AR and asthma, as assessed by the SACRA questionnaire and ACT score, were significantly improved in the patients of the AR+ group. With regard to the pulmonary function tests, the percent predicted vital capacity, and percent predicted forced expiratory volume in one second were also significantly improved. Regardless of whether the patients had previously undergone leukotriene receptor antagonists (LTRA) treatment, the VASs for AR and asthma and the ACT score were significantly improved in the AR+ group. However, the vital capacity (VC), forced vital capacity (FVC) and forced expiratory volume (FEV1) were only significantly improved in the AR+ group that had previously undergone LTRA treatment. Conclusion SACRA questionnaire-based add-on AR treatment would be convenient for the detection of AR by respiratory physicians and would offer improved asthma control. This questionnaire can also be used to assess the therapeutic effects.