Hypereosinophilic syndrome is a disease that presents with a variety of symptoms caused by an abnormal rise in eosinophils in the blood and infiltration into various organs. Typical symptoms include skin symptoms and diarrhea. Diagnosis may be difficult because of the self-limiting phases of the disease with various symptoms. In addition, diagnosis may be delayed by the presence of rare concomitant symptoms, such as muscle pain and numbness. Here, we report the case of a 67-year-old patient with asymptomatic hypereosinophilia with chronic diarrhea, acute-onset weakness, and myalgia. We diagnosed eosinophilic gastroenteropathy, chronic urticaria, and eosinophilic myositis through multiple biopsies of the skin and colon. This case shows that chronic hypereosinophilic syndrome can be exacerbated transiently with acute symptoms and that prompt examination and treatment of hypereosinophilic syndrome based on the involved organs is recommended in a background of eosinophilia.