Objective This study aimed to evaluate factors affecting nutrition and weight loss in patients with head and neck cancer (HNC) undergoing radiotherapy (RT) and investigate the effect of nurse-led support on symptom management. Methods Fifty patients with histologically confirmed HNC receiving definitive or postoperative RT were prospectively enrolled and monitored by a clinical nurse throughout treatment and follow-up (study group). Nutritional intake and bioelectrical impedance analysis (BIA) were recorded. A control group of 45 matched patients without nurse follow-up was recruited for comparison. Results At treatment completion, the study group had a mean weight loss of 3.0 kg (4.35%) vs 5.2 kg (6.9%) in the control group (p=0.03). Moderate dysphagia occurred in 42% of the study group and 62% of the control group (p=0.04). Grade 3 toxicities were 10% more frequent in the control group. Conclusion Nurse-led follow-up significantly improved nutritional outcomes and reduced treatment-related side effects in patients with HNC. These results highlight the value of nursing care in supporting treatment adherence and enhancing multidisciplinary cancer care.