Are Energy Drinks Safe for Athletes?

The recent death of a teen due to caffeine-induced sudden cardiac death (SCD) raises concerns about the safety of caffeine use during exercise. Although millions of athletes consume energy drinks daily without adverse effects, there are rare cases in which caffeine causes heart problems and even death. The safety of caffeine consumption depends on the amount of caffeine consumed and the individual’s cardiac health. Caffeine can exacerbate underlying cardiac arrhythmias, such as long QT syndrome (LQTS), causing SCD with caffeine levels that would not normally be considered toxic.

LQTS is a rare heart disorder in which heart muscles takes longer than normal to recharge between beats. This increases the risk for episodes of serious irregular ventricular heart rhythms. Most arrhythmias occur during or directly after physical activity. Athletes with LQTS are at much higher risk for SCD.

Fig 1: EKG findings in people with Long QT syndrome


In 95 percent of SCD an underlying cardiac disorder is present. However, in most cases the disorder was not previously diagnosed. Often existing signs and symptoms are not recognized. Symptoms of LQTS include dizziness, fainting, palpitations, and occasionally seizures. Any unexplained fainting in an athlete is suggestive of a cardiac disorder and should be thoroughly evaluated. LQTS is usually congenital and inherited so any athlete with a family history of LQTS should also be evaluated.

A thorough screening before participating in sports can help to rule out LQTS. Diagnosis is made based on the athlete’s personal and familial medical history and the results of a 12-lead exercise ECG. Genetic testing can be used to confirm the diagnosis.

Athletes with LQTS should avoid high intensity competitive sport activities. Moderate-intensity and low-intensity physical activities are generally considered to be safe, including biking, golf, skating, and moderate weightlifting. LQTS is usually treated successfully with propranolol, but sometimes requires a pacemaker.

For healthy adults without underlying cardiac disorders 400 mg of caffeine per day or less is considered safe. That is the equivalent of about two energy drinks or 4 cups of coffee. However, the American Academy of Pediatrics advises against the use of caffeinated beverages, especially energy drinks, in children and teens. Additionally, the FDA discourages the use of caffeine powders in both adults and children. One teaspoon of caffeine powder equals about 14 energy drinks.



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