The vagina is an environment that maintains its own balance of microorganisms. When this balance is disrupted, such as when the fungus Candida albicans is allowed to multiply unchecked, a vaginal yeast infection can result. The following are examples of factors that can disrupt the natural balance of microorganisms that live in the vagina:
Antibiotic use: Antibiotics can destroy bacteria that protect the vagina or alter the balance of bacteria that are normally present. A vaginal yeast infection may develop during or after the use of antibiotics taken to treat other conditions such as strep throat.
Steroid use.
Diabetes: This disease can lower the glycogen store in certain vaginal cells.
Diabetes may also raise the sugar content (and pH) of the vagina, which increases the risk for developing a vaginal yeast infection.
Factors that can cause a weakened immune system (for example, HIV/AIDS, steroid use, pregnancy, cancer chemotherapy or other drugs that weaken the immune system).
Use of douches or feminine hygiene sprays.
Scratches or wounds in the vagina (for example, caused during insertion of tampons or other objects).
Underwear that is tight or made of a material other than cotton. (This can increase temperature, moisture, and local irritation.)
Hormonal changes.