I had a Diet Soda habit for three decades, starting in 1980 or so. I noticed no problems except a large, very hard pimple in the VERY CENTER of the back of my neck. It got bigger as I drank more diet soda. When I quit drinking diet soda several years ago, the bump stopped growing. The hard pimple remained. While I was excercising ten years ago, I heard and felt something pop. It was the, apparently, diet soda created pimple on my neck. It had broken open. I wasn't able to get it to the doctor,... Sign in to see full entry.