Discharge is a status report
Healthy discharge is normal and constant. Its volume and texture change across the cycle as oestrogen rises and falls, and it carries away old cells and bacteria — which is what 'self-cleaning' actually means.
The canal is kept at a pH of roughly 3.8–4.5 by lactobacilli, which produce lactic acid. That acidity suppresses the organisms that cause bacterial vaginosis and thrush.
What changes it
- Your period
- Blood is alkaline (pH ~7.4), so symptoms often appear just after bleeding.
- Semen
- Also alkaline — a common trigger for post-sex BV flare-ups.
- Soap, shower gel and douching
- All strip lactobacilli. Douching is consistently associated with worse outcomes, never better.
- Antibiotics
- Kill protective bacteria alongside the target, which is why thrush often follows a course.
- Perimenopause
- Lower oestrogen means fewer lactobacilli, a higher pH and more dryness and irritation.