Updated: Feb 11
The human vagina is acidic.
In good health, the vagina is more acidic than urine or blood. It's more acidic than black coffee, but less acidic than lemon juice. It can have a similar pH to acid rain!
In a previous article Introducing the Vaginal Microbiome (see the vaginal series), I discussed why acidity is important in protecting the vagina against invading bacteria and viruses.
In this follow-up article, I'm getting a bit nerdy with information about how our acidity levels vary with age and typical hormonal cycles.
(I don't presently have any data on acidity for surgically created vaginas or for vaginas of people on masculinizing hormone therapy, sorry.)
Vaginal Acidity is Supposed to Vary… on a Schedule.
Acidity in the vagina can be tested, with a pH strip, and the results are used by doctors in making their diagnosis, and by physios and others in guiding treatment of pelvic or vaginal conditions. Acid levels are measured as pH, with anything below 7 being acidic, 7 being neutral and anything above 7 being alkaline. It’s a simple test, much like testing swimming pool pH, but there’s a few things to consider when deciding what the number means. What is normal in vaginal pH changes with age and with the menstrual cycle. This is mostly due to estrogen, because it stimulates the release of glycogen in the vagina and that provides Lactobacilli with their favourite food. There is a typical pattern of vaginal pH change throughout a woman’s life.
A newborn baby has a pH of 4.5 because it’s been exposed to the mother’s high estrogen during the pregnancy. This gradually moves to almost neutral, around 7, and stays there for our entire childhood.
When puberty begins and we start producing estrogen, numbers of Lactobacilli increase and pH drops, eventually settling into the adult ideal range of a fairly acidic pH 3.5 to 4.5.
With each menstrual cycle, there’s a fluctuation in pH. At ovulation, when estrogen is highest, Lactic Acid production is highest and therefore pH is lowest.
Estrogen is lowest when bleeding starts at the beginning of each menstrual cycle. A pH of 6 is common on Day 2 due to a combination of lower estrogen decreasing the activity of the lactobacilli, and the presence of blood which is naturally neutral, not acidic at all. Over the following days, the vagina recovers its acid level back to that 4.5 or below.
With menopause, the pH number rises a little due to lower estrogen levels. It has been found that a pH consistently greater than 4.5 is about as accurate as measuring Follicle Stimulating Hormone as a test to indicate Menopausal status.
A pH above 4.5 is normal after menopause, which may make menopausal women more susceptible to infections.
If someone has unwanted vaginal symptoms, management of the microbiome can bring relief whether a person is pre menopause, post menopause or somewhere in between.
If your vaginal pH is greater than 4.5, meaning your vagina is not as acidic, it could mean:
- There’s blood in the vagina from menstruation or tissue trauma
- There’s semen present from unprotected intercourse, because semen has an alkaline pH between 7 and 8.
- If there are no symptoms it could be a post-menopausal or pre-puberty normal
- If none of those exceptions apply, then it likely indicates that the microbiome is not Lactobacillus-dominated. And that could mean a variety of conditions including Bacterial Vaginosis or Sexually Transmitted Infections
If your vaginal pH is a healthy acidic 3.5 to 4.5, this suggests a microbiome of normal, healthy flora BUT it doesn’t rule out candidiasis (Thrush) or Aerobic Vaginitis
Finding normal or abnormal pH is not enough to diagnosis any specific disease.
However, lack of acidity has been shown to increase health risks in many ways, even without a specific diagnosis. Because of those risks it can be worthwhile to attempt manage the microbiome and therefore the acid level, even if nothing specific has been found on other tests.
Check out the rest of the series on Vaginal Health HERE!
Want to get our weekly email and hear about new blog posts, other happenings at Forecast Wellness, and some useful health info to boot? Get on our email list here! (I won’t share with anyone else.)
There’s a Forecast Wellness Facebook page too, visit it HERE and like or follow if you’d enjoy seeing regular health tips.
Information provided on this site is intended to be educational. It is not intended to provide medical advice and does not replace advice from your health practitioner.