Vaginal yeast infections are common.

• Yeast infection is the second most common kind of vaginal infection after bacterial vaginosis, which can have similar symptoms. Trichomoniasis, a sexually transmitted disease (STD), is the third most common type of vaginal infection.
• About 75% of women develop at least one yeast infection during their lives. ¹
• Between 40% and 45% of adult women have two or more infections during their lives. ¹
• Less than 5% of adult women have persistent, recurring infections. ¹

Having more than the normal amount of yeast in the vagina does not mean that you will have symptoms or develop a yeast infection. Many women have more yeast than normal in the vagina but never notice or have problems because of it.

Some women are more likely to get vaginal yeast infections because of immune system problems or other medical conditions that upset the body's normal balance between yeast and bacteria. This may include women who have:

• High estrogen levels. Pregnancy and starting some type of hormone therapy, such as birth control pills, are common ways that estrogen levels can rise and cause a yeast infection.
• Poorly controlled diabetes. A change in blood sugar levels can affect the normal balance of organisms in the vagina and cause the excess growth of yeast cells.
• A disease or condition, such as cancer or HIV (human immunodeficiency virus), that affects how well the body fights infections.
• Recently used antibiotics. These medicines upset the normal balance between yeast and bacteria in the vagina. Antibiotics can kill too much "good" bacteria and result in too much yeast growing in the vagina, sometimes causing symptoms of a yeast infection. Taking corticosteroids also increases the risk for yeast infections, because these medicines can weaken the immune system.