I stopped using all products with Sodium Lauryl Sulfate (SLS) over the past 6 months, and the difference it has made is nothing short of miraculous. My skin and hair are now totally normal and healthy.
As for my lips, my seemingly endless chapping, cracking and even bleeding (mostly from my picking at the dry skin), is for the first time in more than 10 years totally gone. I have normal lips! For more than a month now! I can hardly believe it.
The change in my lips did not happen overnight, but gradually over a month or so. I switched to toothpaste and mouthwash with no SLS or harsh ingredients. I also no longer wash my face (which would include my lips) with anything but super mild, natural cleansers that contain no SLS.
For me, this really seems to have done the trick. Since I have not changed anything else in my life or routine, either the removal of SLS was the cure for me, or it is a huge coincidence that everything healed up on its own at this particular time. I have added no new supplements or medications, no stopping of any supplements or medications, no changes in diet or living conditions. So my personal conclusion is that the SLS was the culprit all along. If you read labels, it is in the vast majority of products, but it can be avoided if you make a little effort.
If people would like me to post which skin care / oral care products I have been using, I will gladly do so. I will also try not to post and disappear, in case there are follow up questions.