The stinging pain in urine during menstruation is usually due to the stimulation of menstrual blood and urinary tract infection, as follows: 1. Menstrual blood stimulation: because the vaginal opening and urethral opening are close in local anatomy, vaginal bleeding during menstruation may stimulate the nearby urethral opening, resulting in a stinging sensation when urinating; 2. Urinary tract infection: because of the bleeding state during menstruation, the body’s resistance is poor, and the perineal tissues are stimulated by menstrual blood, which may be complicated by urinary tract infection of the urinary system, further leading to stinging symptoms when urinating.