The National Institutes of Health (NIH) define vaginal yeast infection as an infection of the vagina, most commonly due to the fungus Candida albicans.
Yeast infections are very common. WomensHealth.gov says about 75 percent of women have one during their lives.
WebMD explains yeast is a fungus that normally lives in the vagina in small numbers. A vaginal yeast infection means too many yeast cells are growing in the vagina causing an imbalance.
NIH states this can be caused by antibiotics used to treat other types of infections. They decrease the number of protective bacteria. WebMD adds high estrogen levels caused by pregnancy or hormone replacement therapy can also cause a yeast infection. So can certain health problems, like diabetes or HIV infection.
WomensHealth.gov goes on saying other risk factors for vaginal yeast infection include stress, lack of sleep, poor eating habits, taking certain medicines, including birth control pills and steroids, and hormonal changes during menstruation.
KidsHealth.org says tight underwear or clothes made of synthetic fibers trap heat and moisture and might lead to yeast infections because yeast can thrive in this type of environment. Douches and scented sanitary products can also upset the healthy balance of vaginal bacteria making yeast infections more likely.
Merck Manuals writes after menopause, yeast infections are uncommon except in women who take hormone therapy.
According to WomensHealth.gov, the most common yeast infection symptom is extreme itchiness in and around the vagina. NIH says other symptoms include vaginal and labial burning; abnormal vaginal discharge which ranges from slightly watery, white discharge to thick, white, and chunky (like cottage cheese); pain with intercourse; painful urination; redness and swelling of the vulva.
Yeast infections are treated with antifungal drugs says Merck Manuals. They may be applied to the affected area with cream, inserted into the vagina as a suppository, or taken orally. Some are available without a prescription.