Energy drinks, which contain large amounts of caffeine, could be harmful to your health. From MayoClinic.com Q: Are energy drinks bad for my heart? John / New York They could be. Many energy drinks are loaded with caffeine, sugar and herbal stimulants that can make you alert, but can also make your heart beat markedly faster, putting you at risk of health problems. Caffeine, the main ingredient in energy drinks, isn't directly toxic to the heart. But if you have almost any type of underlying heart disease, even a small amount of caffeine can stimulate the heart and cause problems. Caffeine can increase your blood pressure, and sometimes impair blood flow to your heart. It may trigger abnormal heart rhythms, which can be life-threatening in people at high risk. One problem with energy drinks is that they have become popular as mixers for alcoholic beverages, often in an effort to counteract drowsiness so that you can drink more alcohol. The combination of large amounts of caffeine and alcohol is especially dangerous, since alcohol by itself is known to trigger fast heart rhythms. To avoid this serious health risk â€” even if you don't have heart disease â€” you shouldn't combine alcohol with energy drinks. Another problem is that energy drinks are often consumed quickly, sometimes before exercise. The high amounts of caffeine and sugar can lead to a variety of symptoms, including irritability, nervousness and nausea, sometimes severe enough to require hospitalization. For athletic activity, it's healthier to drink noncaffeinated, low-sugar beverages to prevent dehydration. If you decide to consume an energy drink, read the label and research how much caffeine it contains. If you have heart disease, be cautious about energy drinks and talk to your doctor for individual recommendations.