The enormous popularity of energy drinks has created a worldwide market valued at $21 billion and growing steadily. These sugary and caffeinated beverages can provide a quick energy buzz. Men aged 18 to 34 are the largest group of purchasers, according to the National Center for Complementary and Integrative Health, and almost a third of U.S. teenagers consume energy drinks regularly.

But although energy drinks may boost a sense of physical and mental endurance, they can also take a serious toll on heart health.

What Exactly Are Energy Drinks?

Energy drinks come in two forms. They’re sold in bottles and cans, similar to soft drinks, and as energy shots in small containers of concentrated liquids. The leading brands are Red Bull, Monster, and PepsiCo.

Both types of energy drinks have high levels of caffeine, a stimulant that’s found in coffee and added to many soft drinks. A 16-ounce energy drink can have as much as 240 milligrams of caffeine, and an energy shot can have as much as 200 milligrams. An average 12-ounce can of cola has 35 milligrams of caffeine, and an 8-ounce cup of coffee has roughly 100 milligrams.

The average energy drink has about 42 grams of sugar, compared to an average of 39 grams in a can of cola. However, some energy drinks contain as much as 54 grams of sugar.

Other ingredients that can be found in energy drinks include dietary supplements such as vitamins, minerals, herbs, and other substances, including:

• Taurine (an amino acid)
• Ginseng
• Guarana (also known as Brazilian cocoa)
• Glucuronolactone (a substance produced in the liver)
• B vitamins

Many of the ingredients in energy drinks are stimulants. Guarana, for instance, also contains caffeine, which can raise caffeine content in energy drinks even higher.

Energy Drinks and Unregulated Supplements

The U.S. Food and Drug Administration (FDA) doesn’t regulate dietary supplements in the same way that they oversee food and drugs. The FDA isn’t authorized to approve supplements before they’re sold, and companies that sell supplements aren’t required to prove that their products are safe. Research is limited on the safety and effectiveness of many dietary supplements, including supplements in energy drinks. Some supplements may have side effects or interact poorly with medication.

Energy Drinks and Heart Disease

In high quantities, both caffeine and sugar are linked to adverse effects that can lead to cardiovascular disease. High amounts of caffeine can cause heart palpitations (fluttering or pounding in the chest), high blood pressure, and arrhythmia (irregular heart rhythm). Hypertension and arrhythmias are associated with a risk of stroke, heart attack, and heart failure. High sugar consumption is linked to the onset of diabetes, which damages blood vessels in the cardiovascular system and can lead to heart disease.

Regularly consuming energy drinks can be addictive, leading to dependency and withdrawal symptoms. Having two or more energy drinks a day is considered a high level of intake and has been linked to a range of health risks that can affect the heart and mental health.

In a review of cardiology studies on energy drinks and cardiovascular health, researchers found that energy drinks were associated with dangerous heart problems in both people with preexisting heart conditions and those without known heart ailments.

Heart problems linked to energy drinks include:

• Cardiac arrhythmias, such as atrial fibrillation
• Cardiomyopathy (damage to the heart muscle)
• Myocardial ischemia and infarction (decreased blood flow and heart attack)
• Cardiac arrest (sudden stopping of heartbeat)
• Prolonged QT interval (slow heartbeat)
• Cardiac death

In a study conducted by the U.S. Substance Abuse and Mental Health Services Administration, emergency room (ER) visits involving energy drinks increased from 10,068 in 2007 to 20,783 in 2011. About 42 percent of the 2011 ER visits also involved drug use, including alcohol.

The stimulants in energy drinks mask the effects of alcohol when the two are consumed together. This can lead to binge drinking, particularly among younger people. Combining energy drinks and alcohol can be particularly hazardous for the heart because both alcohol and caffeine consumption can raise blood pressure, raising the risk of more severe heart disease.

Alcohol can damage the kidneys and liver and, along with the high sugar content in energy drinks, can raise the risk of type 2 diabetes. Alcohol and refined sugar should be consumed only in moderation, particularly for people with heart disease.

Health Hazards of Energy Drinks for Adolescents

Even a single energy drink often has caffeine levels above the recommended amount of less than 100 milligrams per day for adolescents, who frequently consume energy drinks. Public health professionals are concerned about the effects of energy drinks on adolescents and young adults. They believe these drinks can increase the risk of heart complications and other health issues, including anxiety and insomnia. Additionally, they suggest that energy drinks may raise the likelihood of using tobacco, alcohol, and illicit drugs.

Although the American Academy of Pediatricians advises against energy drinks for adolescents, 30 percent to 50 percent of young people report consuming these beverages. Likewise, the National Federation of State High School Associations has advised that student athletes not consume energy drinks for hydration. Energy drinks can actually cause dehydration because the effects of caffeine and sugar can cause water to be eliminated from the body.

Healthy Alternatives to Energy Drinks

Heart conditions can lead to fatigue, and people with heart disease may look to energy drinks to improve their stamina. “Taking anything to help with the tiredness? Supplement or energy drinks?” a MyHeartDiseaseTeam member asked.

For people with heart disease, consumption of energy drinks may be particularly risky. You can increase your energy levels in healthier ways. You can discuss these strategies further with your cardiologist and the rest of your health care team.

The American Heart Association offers these tips for boosting energy:

• Drink plenty of water and stay hydrated. Dehydration drains energy.
• Eat healthy meals and maintain a healthy weight. High-calorie meals with too much sugar, salt, or empty calories can make you feel tired.
• Snack on heart-healthy fresh fruits or vegetables.
• Get enough sleep. If you have trouble sleeping, talk to your doctor.
• Stay physically active. Regular exercise has numerous health benefits, such as increasing physical and mental energy, and helping with weight loss.
• Manage stress with self-care or practices such as meditation and deep breathing exercises.

Drinking caffeinated coffee and tea in moderation is generally considered safe for people with heart conditions. Talk with your doctor about how much caffeine is appropriate for you.

Talk With Others Who Understand

MyHeartDiseaseTeam is the social network for people with heart disease and their loved ones. On MyHeartDiseaseTeam, more than 61,000 members come together to ask questions, give advice, and share their stories with others who understand life with heart disease.

What healthy habits help you boost energy? Share your experience in the comments below, or start a conversation by posting on your Activities page.