What is vaginal pH and why does it matter?

Bottom lineVaginal pH measures acidity; a healthy vagina is slightly acidic at about 3.8 to 4.5, maintained by protective lactobacilli that keep infections at bay. pH rises (becomes less acidic) with bacterial vaginosis, periods, semen, douching, and low estrogen; a high pH is linked to BV, but pH test strips only flag that something is off, not what, so protect healthy pH by avoiding douching and scented products.

Vaginal pH is a measure of how acidic the vagina is. A healthy vagina is slightly acidic, with a pH of about 3.8 to 4.5. That acidity is created by protective lactobacilli bacteria and is your first line of defense against infection.

Why acidity protects you

The acidic environment makes it hard for harmful bacteria and yeast to overgrow. When pH stays in the healthy range, the ecosystem stays balanced. When it rises above about 4.5, protective bacteria struggle and infection-causing organisms can take over.

What raises vaginal pH

• Bacterial vaginosis - both a cause and a result of a higher pH
• Periods - menstrual blood is less acidic, so pH rises during your period
• Semen - alkaline, so pH can shift after unprotected sex
• Douching and harsh washes - strip acidity and protective bacteria
• Low estrogen - in menopause or breastfeeding, pH tends to rise

What it means in practice

A higher-than-normal pH is closely linked to BV, which is why at-home "vaginal pH test strips" exist. But a strip only tells you pH is off, not why, and a normal pH doesn't rule out a yeast infection (yeast can occur at normal pH). Treat a strip as a clue, not a diagnosis.

The best way to protect healthy pH is to leave the vagina alone: no douching, no scented products, and wash only the vulva with water. The microbiome does the rest. For the science, see our vaginal microbiome guide.

Femora lets you log symptoms across your cycle so you can see when changes line up with your period (when pH naturally rises) versus something worth checking.