Background: Energy drinks are flavored beverages containing high amounts of caffeine and typically other additives, such as vitamins. These drinks are readily available in grocery stores, vending machines, convenience stores, and bars and other venues where alcohol is sold. Research suggests that certain additives may compound the stimulant effects of caffeine. Energy drinks were originally marketed to appeal to youths and were reported to have been consumed by 30 to 50% of children, adolescents, and young adults. Consumption of energy drinks is a public health concern because a growing body of scientific evidence documents harmful health effects of energy drinks, particularly for children, adolescents, and young adults. Methods: National estimates of Emergency Department (ED) visits involving energy drinks were analyzed using data from the 2005 to 2011 Drug Abuse Warning Network (DAWN). We examined trends by age and gender, reason for ED visit (e.g., adverse reaction, misuse or abuse) and other drugs identified in these ED visits. Results: The estimated number of ED visits involving energy drinks doubled from 10,068 visits in 2007 to 20,783 visits in 2011. There were more male patients than female patients; visits doubled from 2007 to 2011 for both males and females. In each year from 2007 to 2011, there were more patients aged 18 to 39 than patients in other age groups; the largest increase was seen among patients aged 40 or older, for whom visits increased 279% from 1,382 visits in 2007 to 5,233 visits in 2011. In 2011, 58% of energy drink-related ED visits involved energy drinks only; the remaining 42% involved other drugs. Conclusion: Between 2007 and 2011, the number of ED visits involving energy drinks increased, underscoring previously published findings. The popularity of these drinks persists although large amounts of caffeine can cause adverse effects such as insomnia, nervousness, headache, fast heartbeat, and seizures that are severe enough to require emergency care. This report validates claims that energy drinks can be dangerous when used alone or in combination with other drugs or alcohol. A new finding in this report suggests that older adults may also be vulnerable to the effects of energy drinks, even though the drinks are marketed with claims of having a positive impact on energy and concentration. This may be due to interactions of energy drink components with prescription medications.