Stomach problems in my case and many other peoples, involve the entire digestive track and includes vomiting, diarrhea, indigestion severe enough to be classified as acid re-flux and severe abdominal cramping. I was attempting to be sensitive to other people sensitivities by not going into detail. There is also a difference in the amounts needed to be taken and the number of people who have these problems that must be taken into consideration when attempting to compare two completely different medications side affects. There is a difference in the number of people who experience severe problems. Most who take NSAID's only experience mild symptoms unless they take large quantities over an extended period of time. Most people who have problems with Metformin tend to have it with within 24 hours of their first dose. For many it gets better within a few weeks, but for some, it only gets worse.