For Endoscopic Thoracic Sympathectomy (ETS), ideal candidates are primarily young patients diagnosed with primary hyperhidrosis. It is imperative that patients undergoing surgery receive comprehensive information regarding the risk of compensatory hyperhidrosis and provide informed consent. Generally, patients should be at least 17-18 years old. This age threshold is advised to ensure hormonal stability, as high hormonal activity during adolescence (typically before 17) can influence outcomes. Therefore, ETS is generally not recommended before the age of 17, unless absolutely necessary.