Women who self-treat yeast infections may overlook these surprising yeast-promoting factors, as can many doctors: High sugar levels in vaginal fluids. Diabetes can raise glucose levels in vaginal fluid, which can feed yeast. Overindulging in sweets or alcohol can have the same effect, says Dr. Mercer. Low immunity. An underactive thyroid gland, chronic stress, and HIV all mute your immune response, therefore hampering your first line of defense against infection. Spermicides. Sperm-killing contraceptives can also knock off friendly vaginal bacteria that normally help keep yeast in check. More from Prevention: 5 Reasons It Hurts Down There
