The vagina cleans itself, and washing it causes the problem
Douching raises the risk of exactly the infection it is meant to prevent.
A healthy vagina sits between pH 3.8 and 4.5, maintained by lactobacilli that produce lactic acid. That acidity is the defence. Douching, scented washes and soap raise the pH and strip the bacteria, which is why studies consistently find douching associated with a higher rate of bacterial vaginosis, not a lower one.
The vulva — the outside — can be washed with warm water. The vagina requires nothing. Semen is alkaline at around pH 7.2 to 8.0, which is why some people notice a change in odour for a day afterwards; that is the pH recovering and not a sign of anything wrong.
