There is ethanol in it, and it has very strong properties that tend to eat away at the lining of the stomach, over time you can develop gastritis, pancreatitis, ulcers, and other problems with the stomach from consumption of alcohol. Hope this helps.
Maybe it's the ingredients in it, or other things
Not just getting sick it also is a prime factor in stomach and esophageal cancer as the abuse of alcohol attacks the lining of the aforementioned body parts.