Bacterial vaginosis (BV) is a form of vaginal inflammation due to an overflow of the normal bacteria in the vagina, which throws off the delicate balance. This is not an sexually transmitted infection (STI), but can increase your risk of getting an STI e.g. Chlamydia. Although it can afflict women of any age, bacterial vaginosis is more common in women in their reproductive years. The exact cause is unknown, however certain behaviours like unprotected intercourse or regular douching increase your risk.