Caffeinated alcohol drinks have been responsible for deaths in some cases maybe because some people fail to realize that the two chemicals are very strong when they are by themselves so putting them together could magnify the toll it will take on ones nervous system and heart rate without them even noticing and so could be considered unsafe.
No, caffeinated alcohol drinks are not unsafe because its just caffeine and alcohol. Unless there is some kind of deadly combination between caffeine and alcohol, then it must be safe. People drink caffeine, people drink alcohol. People drink both, why not at the same time. There is nothing wrong with caffeinated alcohol drinks.