What causes vaginal yeast infections?
Vaginal yeast infections occur when new yeast is introduced into
the vaginal area, or when there is an increase in the quantity of yeast already
present in the vagina relative to the quantity of normal bacteria. For example,
when the normal, protective bacteria are eradicated by antibiotics (taken to
treat a urinary tract,
respiratory, or other types of infection) or by immunosuppressive drugs,
the yeast can multiply, invade tissues, and cause irritation of the lining of
the vagina (vaginitis).
Vaginal yeast infections can also occur as a result of injury to
the inner vagina, such as after chemotherapy. Also, women with suppressed immune
systems (for example, those taking cortisone-related medications such as
prednisone) develop vaginal yeast infections more frequently than women with normal
immunity. Other conditions that may predispose women to developing vaginal yeast
infections include
diabetes mellitus, pregnancy, and taking
oral contraceptives.
The use of douches or perfumed vaginal hygiene sprays may also increase a woman's risk of
developing a vaginal yeast infection.
A vaginal yeast infection is not considered to be a
sexually transmitted infection (STD), since Candida may be present in the normal
vagina, and the condition
does occur in celibate women. However, it is possible for men to develop
symptoms of skin irritation of the penis from a yeast infection after sexual intercourse with an infected partner.