Caffeine may increase heart rate, body temperature, blood flow to the skin & extremities, blood pressure, blood sugar levels, stomach acid secretion and production of urine (diuretic).hile consuming moderate amounts of caffeine does not seem to have long-term detrimental effects, consuming larger amounts of caffeine (1000 mg or about ten 6-oz cups of coffee a day) on a regular basis may be linked to conception problems, increased episodes of heartburn, and changes in bowel habits.