Background: A total of 8,303 individuals (4.3%) with adverse reactions (n=191,860) after vaccination developed serious conditions or died. Such health developments could cause people not vaccinated yet or waiting for a booster shot to become fearful of the vaccination., Methods: The 3-month (July-September 2021) clinical data of 41 patients from the family medicine department of a single medical center were analyzed retrospectively to determine risk factors and to investigate the clinical course to identify the cause of symptoms in detail., Results: A significant number of older adults aged over 50 years reported experiencing general weakness (P=0.026) but fewer incidences of fever than patients aged 50 years or younger (P=0.011). Eighteen of the 41 patients were requested to visit more than twice or consult a specialist. In 14 patients, the symptoms were explained by other medical causes., Conclusion: The primary physician has a pivotal role in thoroughly evaluating patients who complain of adverse effects after vaccination, considering the broad multitude of symptoms and medical conditions presented. To thoroughly evaluate and appropriately advise patients with adverse reactions to their chosen vaccine, taking detailed medical history and nutritional counseling are required to identify possible underlying causes, resolve symptoms, and educate them on self-care and regarding vaccines.