What are the long term negative effects of caffeine consumption?

Multiple: Long term excess caffeine use can increase blood pressure, cause headaches, lack of restful sleep, palpitations, tremors, anxiety, nervousness, abdominal pain/cramps, diarrhea. I tell patients 1 cup of coffee in morning, and 1 caffeinated beverage early afternoon is unlikely to cause problems.

Not that we know of: Actually, as drugs go, caffeine consumption seems to be relatively safe (i guess this is why so many of us use it). In some people excess caffeine (more than 500mg/day) may cause elevated blood pressure but, in general, most studies suggest that it is safe, even in moderate amounts. There is even a small study that shows the more caffeine one drinks, the less risk of Parkinson's disease.