Frequent urination during menstruation is caused by drinking too much water, urethritis and cystitis. 1. Drinking too much water: Drinking a lot of water during menstruation will lead to an increase in the amount of urine, which is a normal physiological phenomenon, and the number of times of urination will also increase, thus causing frequent urination. 2. Urethritis: If you do not pay attention to hygiene during menstruation, so that bacteria enter the urethra, may be stimulated by inflammation, it will cause frequent urination during menstruation, accompanied by urinary pain, urgency and other symptoms. 3. Cystitis: During menstruation, the body’s resistance decreases, and pathogenic bacteria and bacterial reproduction may occur in the bladder, causing edema and erosion of the mucous membrane of the bladder triangle and bladder neck, leading to frequent bladder contractions, which in turn lead to frequent urination and incomplete urination. When patients with symptoms of frequent urination during menstruation, after excluding physiological factors, it is recommended to go to the hospital in time for examination and treatment according to the condition.