Dr. Ben Kim's newsletter is always a source of sensible health info. Here's what he has to say:
Over the years, I have found that many people aren't aware that soap should not be used to clean the vaginal opening, the tip of the penis (urethral opening), and the anal sphincter.
Regularly applying soap to these areas can cause the mucosal lining in these areas to become dry and unhealthy. A chronically dry mucosal lining can lead to a number of uncomfortable health conditions, such as anal fissures, lichen sclerosus, chronic inflammation and a tendency to experience infections.
If you use soap to clean your body, you should limit its contact to your skin. Your skin is lined with sebaceous glands that secrete an oily substance called sebum, which serves to keep your skin waterproof and resistant to infection by undesirable microorganisms.
Typically, the presence of sebum prevents soap from drying out skin to a point where significant health challenges can arise. Still, unless you work with grease and oil, it's best to use soap sparingly - just enough to remove objectionable odors and to feel clean and refreshed.
The mucosal linings of the vaginal opening, the penile opening, and the anal sphincter don't secrete sebum to offer protection against the drying effects of soap. Actually, the labia minora does contain some sebaceous glands, but in most women, there aren't nearly enough sebaceous glands in this region to keep the vaginal opening healthy if regularly washed with soap.
So how do you wash the vaginal opening, the penile opening, and the anal sphincter? Ideally, with warm or hot water. And when more intense cleaning is desired, you can use warm or hot salt water.
I've worked with enough people who have experienced health challenges from using soap in the private areas to know that this advice is worth heeding. Please share this information with family and friends, as my experiences have led me to believe that most people aren't aware of this issue.