Bleeding during urination in men is a common cause: 1. Acute infection of the urinary tract, which can occur with frequent and urgent urination accompanied by red urine. Patients often have a history of antecedent infection, and severe patients may even have chills or fever, it is recommended that routine urinalysis and urine culture tests be performed to further confirm the presence of urinary tract infection. 2. 3. If you have urinary tumors such as kidney tumors, ureteral tumors or bladder tumors, they may cause local mucosal destruction and bleeding, which can be manifested as flesh-eye hematuria throughout the whole process, usually without obvious pain in the early stage. When the tumor increases in size or is accompanied by invasion of surrounding organs, pain can appear and needs to be identified by CT examination of the urinary system.