Objectives. I-131 therapy for differentiated thyroid cancer (DTC) could induce adverse effects. The purpose of this study was to report and analyze symptoms after I-131 treatment within the hospitalization and present relevant medical intervention. Methods. I-131 doses ranging from 3.7 to 9.25 GBq (100–250 mCi) were administrated for thyroid remnant ablation or treating DTC metastases. 117 patients with DTC for I-131 therapy were monitored through the video and intercommunicating with standardized questionnaire at different time points after I-131 oral administration. Adverse effects were recorded and relevant clinical factors were analyzed. Results. Among all the 117 patients, 55 cases complained of neck’s pain or swelling and 79 cases presented with gastrointestinal symptoms. Pain or swelling of salivary gland occurred in 15 patients, headache and vertigo in 10, insomnia in 9, vocal cord paralysis in 6, fatigue or general malaise in 6, and foreign body sensation in 5. Body numbness and urinary symptoms were observed in only 1 case, respectively. Those side effects were related with sex, pre-I-131 treatment TSH levels, frequency of I-131 therapy, and lymph node metastases. Conclusions. Short-term side effects after I-131 therapy for DTC patients varied individually; severe symptoms were not uncommon but generally did not need emergent medical intervention.