Causes

The cause depends on what type of vaginitis you have:

• Bacterial vaginosis. This most common cause of vaginitis results from a change of the normal bacteria found in your vagina, to overgrowth of one of several other organisms. Usually, bacteria normally found in the vagina (lactobacilli) are outnumbered by other bacteria (anaerobes) in your vagina. If anaerobic bacteria become too numerous, they upset the balance, causing bacterial vaginosis.

  This type of vaginitis seems to be linked to sexual intercourse — especially if you have multiple sex partners or a new sex partner — but it also occurs in women who aren't sexually active.

• Yeast infections. These occur when there's an overgrowth of a fungal organism — usually C. albicans — in your vagina. C. albicans also causes infections in other moist areas of your body, such as in your mouth (thrush), skin folds and nail beds. The fungus can also cause diaper rash.

• Trichomoniasis. This common sexually transmitted infection is caused by a microscopic, one-celled parasite called Trichomonas vaginalis. This organism spreads during sexual intercourse with someone who has the infection.

  In men, the organism usually infects the urinary tract, but often it causes no symptoms. In women, trichomoniasis typically infects the vagina, and might cause symptoms. It also increases a women's risk of getting other sexually transmitted infections.

• Noninfectious vaginitis. Vaginal sprays, douches, perfumed soaps, scented detergents and spermicidal products may cause an allergic reaction or irritate vulvar and vaginal tissues. Foreign objects, such as tissue paper or forgotten tampons, in the vagina can also irritate vaginal tissues.
• Genitourinary syndrome of menopause (vaginal atrophy). Reduced estrogen levels after menopause or surgical removal of your ovaries can cause the vaginal lining to thin, sometimes resulting in vaginal irritation, burning and dryness.