Does the pH of my vagina matter?

If you’ve ever worn black underwear, you may have noticed what looks like fading in the crotch area. Maybe you thought it was just you, or that some bleach had gone astray in the wash. Turns out - that’s all thanks to the acidity of your vaginal fluids, which have about the same pH as a cup of black coffee.

A normal pH (the scale that measures acidity vs bases, which you might remember from high school chem) of a vagina is between 3.8 and 4.5, which is classed as “moderately acidic.” (Vinegar is a 2, FYI.) This “normal” can fluctuate as you go through different life stages. When you’re in your reproductive years, normal is ideally below 4.5, although that can go up right before you get your period, or when you’re hitting menopause.

Why does this matter, beyond being a fun fact? Maintaining an acidic vaginal environment is important to keep things happy and in balance down there. It discourages the growth of unhealthy bacteria, for instance, which can often be a culprit in yeast infections. If your vagina is too acidic, that can be a challenge if you’re trying for a baby. Why? When you’re having penetrative sex, the pH of your vagina temporarily adjusts to become more alkaline to suit the sperm, who prefer their environments closer to seawater than battery acid on the pH scale.

If you’re unsure whether your vaginal pH is out-of-whack, you can take a test - although symptoms like itching, burning or an unpleasant odour will often be your best guide to get it checked out. If you want to be proactive about keeping it in the acidic sweet spot, take probiotics, avoid anything harsh soaps (see this post about vaginal hygiene) and use barrier protection if you’re having penetrative sex.