Can too much caffeine cause abdominal pain & where?

Usually not: Caffeine by itself should not cause abdominal pain; that being said, most caffeinated beverages can irritate an already existing stomach ulcer.

Too much: Caffeine can cause dehydration and secondarily severe constipation and abdominal pain that can vary from low central to left sided abdominal pain to pain thru out the abdomen. Like everything else moderation is best.