What causes a vaginal yeast infection?
Most yeast infections are caused by a type of yeast called Candida albicans. A healthy vagina has many bacteria and a small number of yeast cells. The most common bacteria, Lactobacillus acidophilus, help keep other organisms—like the yeast—under control. When something happens to change the balance of these organisms, yeast can grow too much and cause symptoms. Taking antibiotics sometimes causes this imbalance. The high estrogen levels caused by pregnancy or hormone replacement therapy can also cause it. So can certain health problems, like diabetes or HIV infection.
