What does untreated BV lead to?

Most of the time, bacterial vaginosis that's picked up and treated promptly doesn't lead to anything beyond the original discomfort. But leaving it, whether that's not seeking treatment or not finishing a prescribed course, does carry real, well-documented risks. Here's the full rundown of what untreated BV has been linked to.

A higher chance of catching other infections, including HIV

BV disrupts the vagina's natural defences by making it less acidic, which makes it easier for other infections to take hold. The CDC specifically flags an increased risk of acquiring HIV, chlamydia and gonorrhoea, and notes that if you already have HIV, untreated BV can also increase the chance of passing it on to a partner. Whether BV itself should be considered sexually transmitted is a separate and genuinely unsettled question, which we've covered in Can BV mean STD?

Pelvic inflammatory disease (PID)

If bacteria from BV travel up into the uterus and fallopian tubes, it can develop into pelvic inflammatory disease. PID causes inflammation and, left unmanaged, can lead to chronic pelvic pain and permanent scarring of the reproductive organs, which is one of the more common causes of infertility. This is one of the more serious reasons doctors recommend treating BV rather than waiting to see if it clears on its own.

Fertility and IVF outcomes

Beyond PID, BV has also been linked to lower success rates in IVF and a higher risk of fallopian tube blockages, according to fertility clinic guidance. If you're undergoing or planning fertility treatment, this is a good reason to get any BV symptoms checked and treated before starting, rather than assuming it's a minor, unrelated issue.

Pregnancy complications

This is one of the better-established risks. Untreated BV during pregnancy is linked to a higher chance of premature birth and low birth weight, and some research also points to a higher risk of miscarriage and postpartum endometritis (infection of the womb lining after delivery). Both the CDC and NHS treat pregnancy as a reason to prioritise BV treatment rather than delay it, and any change in vaginal discharge during pregnancy is worth flagging to a midwife or GP promptly.

Complications after gynaecological procedures

Active, untreated BV has also been associated with a higher risk of developing an infection after pelvic surgery, including procedures like a hysterectomy or dilation and curettage (D&C). If you have BV symptoms and a procedure like this scheduled, it's worth raising it with your surgical team rather than assuming it isn't relevant.

What untreated BV doesn't do

To be clear about what isn't on this list: BV does not transform into an STI, no matter how long it's left, and it doesn't spread through the body the way a systemic infection would. The risks above come from BV weakening your defences and creating opportunities for other problems, not from BV itself becoming something more dangerous. For how long BV typically takes to become a problem, and when it's worth escalating beyond home care, see What Happens If You Leave BV Too Long?

If you want to understand what's actually triggering your BV in the first place, we've broken that down in What Is The Main Cause Of BV?, and if you're looking at ongoing support once it's cleared, see Can I Get Rid Of BV By Taking Probiotics?