Is a Yeast infection caused by bacterial overload or yeast overload?

A yeast infection is primarily caused by an overgrowth of yeast, particularly Candida species, rather than bacterial overload. While bacteria and yeast coexist in the body, an imbalance—often due to factors like antibiotics, hormonal changes, or a weakened immune system—can lead to a yeast infection. In contrast, bacterial infections are typically caused by an overgrowth of harmful bacteria.