The redness of the toilet water after urination may be caused by menstruation, or considered to be caused by vesiculitis, glomerulonephritis, pyelonephritis, cystitis and other diseases. 1. Menstruation: Normal female endometrium can appear cyclic shedding, manifested as vaginal bleeding, if the body does not have other symptoms, the redness of the toilet water after urination is mostly considered to be due to menstruation. 2. Vesiculitis: Vesiculitis may be caused by pathogen infection, alcoholism, perineal injury, excessive sexual life and other factors. Patients may experience pain, hematospermia, hematuria, dysuria and other symptoms, which are manifested as red toilet water after urination. 3. Glomerulonephritis: Glomerulonephritis may be caused by genetic, infection, immunity, metabolism, tumor and other factors. Patients may have symptoms such as hematuria, edema, hematuria, etc. Some patients may have redness of toilet water after urination. 4. Pyelonephritis, cystitis: Pyelonephritis, cystitis, etc. can also cause hematuria and reddening of toilet water. In addition, urinary tract tumors and other causes can also lead to red toilet water after urination, we recommend that patients go to the regular hospital to find out the cause of the disease in a timely manner. Once diagnosed, patients need to actively take relevant treatment measures to avoid delaying the condition.