If you routinely reach for an energy drink to give you a boost during the day, you may be doing your body more harm than good. The main sources of energy in these beverages are sugar and caffeine. And while they may provide that short burst of power, in the long run you’ll feel more tired.

Energy drink sales globally are over $57 billion, and they are the second most popular dietary supplement among U.S. teens and young adults behind multivitamins. Most energy drinks contain between 100 and 300 milligrams of caffeine. The Mayo Clinic Health System says that up to 400 milligrams of caffeine daily is safe for most adults. People who are pregnant or breastfeeding should limit their intake to 200 milligrams or less per day,

According to USA Today, caffeine acts like adrenaline in the body and when  it wears off, energy plummets.

“Everyone breaks down the caffeine in the body at different rates,” notes Kelly Morrow, a registered dietitian and clinical affiliate at the Osher Center for Integrative Medicine at the University of Washington. “Those who drink a lot or break it down slowly may have trouble sleeping and may feel anxious. Depending on how much caffeine energy drinks contain — some people have had a dangerous irregular heart rhythms after sipping energy drinks. I would not recommend drinking caffeinated energy drinks to anyone with heart disease, high blood pressure, insomnia, anxiety, depression, or other mental health problems.”

The sugar in these drinks can also be problematic, causing blood sugar spikes that temporarily increase energy levels, but lead to a crash a few hours later. The long-term effects of drinking sugary beverages include insulin resistance and a higher risk of developing type 2 diabetes. Because a high intake of sugar can lead to health problems, the Dietary Guidelines for Americans recommends limiting intake of added sugars to no more than 10% of total daily calories. For example, in a 2,000-calorie diet, no more than 200 calories or 12 teaspoons should come from added sugars, says Mayo Clinic Health system.

However, one 16-ounce can of Juice Monster Energy Juice Pacific Punch supplies 210 calories and 47 grams of extra sugar, which is roughly 12 teaspoons — an entire’ s day worth of added sugar.

Energy drinks may also have artificial sweeteners like sorbitol, xylitol and sucralose that are known to worsen irritable bowel symptoms like bloating, gas, and diarrhea. And they may also contain herbal supplements such as ginseng and guarana to increase energy and mental alertness. But experts caution that the research on the safety and effectiveness of these substances is limited. Herbal supplements can also interact with prescription medications so ask your healthcare professional if it’s safe to take them.

While an occasional energy drink may be okay, it’s probably better to boost your energy naturally, says USA Today. Stay hydrated, practice good sleep hygiene, eat regular balanced meals, exercise, and practice stress reduction techniques like meditation.