Q: Dear Dr. Mao,
I am prone to yeast infections. What causes them?
A: Candida albicans is a naturally occurring yeast that flourishes in moist areas, such as the digestive tract, the vagina, and skin folds. Ordinarily, its population is kept in check by bacteria that live in the same areas. When normal bacteria are disturbed by antibiotics, however, yeast populations can grow to abnormally high levels.
For women, the most common symptom of excess candida is a vaginal yeast infection, as marked by itchiness, redness, burning on urination, and a yeasty odor. However, candida can also overpopulate in the mouth (thrush), in the warm moist environment under a diaper (diaper rash), and in other areas.