Reason behind the “bleach” patch on your underwear
ArchiveFirst published March 1, 2025. It may not reflect later developments.
Why Your Underwear Has “Bleach” Patches
The internet has made it easy to solve everyday mysteries, including one that many women have wondered about: Why do underwear sometimes have bleach-like stains?
The Science Behind It These patches aren’t caused by washing machines but by the natural pH levels of the vagina. The vagina is naturally acidic, with a pH range of 3.8-4.5. A viral Twitter post explains: “It’s completely normal to discover lighter patches in a woman’s underwear… a healthy vagina is one that can bleach the fabric.”
A Self-Cleaning System Dr. Vanessa MacKay from the Royal College of Obstetricians and Gynaecologists states, “The vagina has a self-cleaning mechanism through natural secretions. It contains beneficial bacteria that serve to protect it.” This acidity helps maintain vaginal health by preventing infections.
What It Means for You According to the National Institutes of Health, a vaginal pH of 3.8-5.0 is healthy. Dr. MacKay reassures that clear or white discharge is normal, and disrupting this balance can lead to infections. So, these patches are simply a sign of a well-functioning body.
