I have an upper GI question?

my friend had an upper GI done today with the barium stuff that he had to drink and the doctor told him that it might make him constipted but instead it did the opposite and he had very bad diarrhea right after the test. is this normal? like i mean does this happen sometimes? he called the doctor but they didnt call back yet. should we be worried or could it just be from the stuff that he had to drink?