Im a 20year old lesbian i have been with my girlfriend for 5years shes22, for the past 2years she has been getting yeast infections what is the cause?

Recurrent yeast: Having vaginal yeast is normal; usually there is no apparent reason or explanation when they cause irritation, itching and sometimes discharge. Some episodes are triggered by other health problems, especially diabetes, or by taking antibiotics. And lesbian partners share most vaginal microorganisms; although yeast isn't considered an STD, it might reduce her recurrences if you also are treated.