A yeast infection, also known as candidiasis (pronounced: can-dih-die-uh-sis), is the name for a common infection caused by a type of yeast-like fungus called candida.
Yeast infections usually occur in warm, moist parts of the body, such as the mouth and moist areas of skin. When they cause an infection in the vagina, it is known as vulvovaginal candidiasis.
Candida can overgrow for many reasons. Stress, pregnancy, and illnesses that affect the immune system may allow yeast to multiply, as can certain medicines. These include some birth control pills and steroids. Or if you're taking antibiotics, such as for strep throat, the antibiotics can kill "good" bacteria that also live in the body and normally keep the growth of candida in the vagina in check. Yeast also can flourish if a girl's blood sugar is high. Girls who have diabetes that isn't controlled are at a higher risk for yeast infections.
Many girls find that yeast infections tend to show up right before they get their periods because of the hormonal changes that come with the menstrual cycle. Clothing (especially underwear) that is too tight or made of materials like nylon that trap heat and moisture might lead to yeast infections because yeast can thrive in this type of environment. And douching and using scented sanitary products can upset the healthy balance of bacteria in the vagina and make yeast infections more likely.
Yeast infections can happen to any girl, and they're not related to having sex — although they occasionally can be spread from one sexual partner to the other. This is quite rare, though, and the partner of someone who has a yeast infection does not automatically have to be treated. Yeast infections that are spread through sex are not considered a sexually transmitted disease (STD). A doctor won't be able to tell how you got a yeast infection, but will be able to tell you if you really have one, and if so, how to treat it.
