It says, "Should the vagina's pH change and become more basic (less acidic), weakening this natural defense mechanism, other bacteria will proliferate in the vagina. "
Most soaps and cleaning agents are basic. This could be one reason that people might get infections from using a cup. A generic soap, even if it is "mild", is basic. Also, hydrogen peroxide is slightly basic. Obviously, you are going to try to rinse it thoroughly before inserting, but maybe a residue remains. That could be a big reason why people get infections from cups. Has anyone had this experience?