A change in the balance of the yeast and bacteria that normally live in the vagina can result in vaginitis. This causes the lining of the vagina to become inflamed. Factors that can change the normal balance of the vagina include the following:
Use of antibiotics
Changes in hormone levels due to pregnancy, breastfeeding, or menopause
Douching
Spermicides
Sexual intercourse
Infection
Learn more about vaginitis at ACOG. (Source: ACOG)