A douche is a method of rinsing or cleaning out the vagina by squirting water or other solutions into it. Approximately 37 percent of American women between the ages of 15 and 44 douche regularly. A few of the reasons that women give for douching include reducing odors, avoiding sexually transmitted diseases (STDs), and rinsing away blood after a menstrual period. However, it is best to let the vagina clean itself, since the chemical balance of the vagina is highly sensitive.