Urine that flows out while brushing your teeth is classified as urinary incontinence. It can be caused by stress incontinence, urethral injury, urinary tract infection and other reasons. 1. Stress incontinence: for example, pelvic floor muscle relaxation, abdominal pressure or pelvic pressure increases, which can cause the phenomenon of urine flow out when brushing teeth. 2. Urethral injury: For example, surgery, examination, catheter stimulation through the urethra, or traumatic injury to the urethra can also cause urine to flow out when brushing teeth. 3. Urethral infection: common cystitis, urethritis, prostatitis, etc., may also cause the symptom of urine flow out when brushing teeth. There may be other reasons why urine comes out when you brush your teeth, so it is recommended that you go to the hospital in time for a checkup to determine the cause of the problem and follow the doctor’s instructions for treatment.