Post-irradiation xerostomia remains a significant quality of life concern for patients with head and neck cancers. Conventional therapies offer limited effectiveness. This study aims to investigate the therapeutic potential of office-based salivary ductal steroid irrigation in patients with post-irradiation xerostomia. This single-center observational study recruited 147 head and neck cancer patients suffering from post-irradiation xerostomia between November 2020 and October 2022. All included subjects received at least one round of successful salivary ductal cannulation and irrigation. The primary measure of efficacy was improvement in subjective xerostomia and objective salivary amylase levels. A logistic regression was employed to evaluate factors affecting treatment responsiveness. The response rate among nasopharyngeal cancer (NPC) patients was 74.8%, and that among non-NPC cancer was 65.6%, without significant intergroup differences. The statistical analysis revealed no significant influence of age, gender, or disease stage on treatment responsiveness. Post-treatment salivary amylase levels were significantly higher in responsive non-NPC patients. In conclusion, salivary ductal steroid irrigation emerged as a promising therapeutic modality for the management of post-irradiation xerostomia in head and neck cancer patients. While no explicit factors were predictive of responsiveness, the high rate of symptom improvement suggests that this therapy may be a viable alternative for patients that are refractory to standard treatments.