Individual responses to caffeine vary, and these drinks should be treated carefully because of how powerful they are. Energy drinks’ stimulating properties can boost the heart rate and blood pressure (sometimes to the point of palpitations), dehydrate the body, and, like other stimulants, prevent sleep.
Energy drinks should not be used while exercising as the combination of fluid loss from sweating and the diuretic quality of the caffeine can leave the user severely dehydrated.
This is from Brown university heath
Earlier this month, a new study found a surprising number of caffeine overdose reports to a Chicago poison control center. These involved young people taking alertness pills such as NoDoz or energy drinks, sometimes mixed with alcohol or other drugs. During three years of reports to the center, the researchers found 265 cases of caffeine abuse. Twelve percent of those required a trip to the hospital. The average age of the caffeine user was 21.
“Young people are taking caffeine to stay awake, or perhaps to get high, and many of them are ending up in the emergency department,” said Dr. Danielle McCarthy of Northwestern University, who conducted the study. “Caffeine is a drug and should be treated with caution, as any drug is