Study Finds Energy Drinks May Cause Cardiovascular Risks

Jennifer Gershman, PharmD, CPh
Published Online: Tuesday, June 4th, 2019
Energy drinks have gained popularity and have become the most popular dietary supplement consumed in the United States by teens and young adults.1 

Approximately 30% of people ages 12-17 years in the US consume energy drinks on a regular basis.1 These drinks usually contain caffeine at levels of 70-240 mg in a 16-oz. drink, and 113-200 mg in an energy shot. As a comparison, cola contains about 35 mg of caffeine, and an 8-oz cup of coffee contains about 100 mg.  Other ingredients contained in energy drinks may include guarana (another source of caffeine), sugars, taurine, ginseng, B vitamins, glucuronolactone, yohimbe, carnitine, and bitter orange.

Evidence suggests that consuming energy drinks may cause adverse health effects including cardiovascular, sleep, digestive, and dehydration problems.1

A recent study published in the Journal of the American Heart Association showed that individuals who consumed 32 ounces of energy drinks in 60 minutes had QTc prolongation (abnormal electrical heart activity) and increased blood pressure 4 hours later, and this was found to be statistically significant.2 This was a randomized, placebo-controlled, crossover clinical trial conducted at a university campus setting (July 2017-December 2017). The study involved 34 healthy volunteers ages 18-40 years who were willing to avoid consuming caffeine and energy drinks for 48 hours before each study day to be eligible as study participants. Individuals were excluded from participation if they had any known medical condition, were pregnant or breastfeeding, current smokers, had a baseline QTc > 450 ms, or blood pressure > 140/90 mm Hg. Patients taking any chronic prescription or over-the-counter (OTC) medications were excluded except those taking oral contraceptives for over 1 month.2

Study participants consumed 32 ounces of 1 of 2 commercially available energy drinks or a placebo on 3 separate days with a 6-day washout period in-between.2 Patients were monitored with an electrocardiogram to determine the electrical activity of the heart during the study. The energy drinks contained 304-320 mg of caffeine/32 ounce drink along with other ingredients including taurine, glucuronolactone, carnitine, guarana, and panax ginseng.

This is the largest controlled study showing that acute consumption of a 32 ounce caffeinated energy drink significantly prolongs the QTc interval compared with placebo. Some study limitations include that long-term effects of energy drink consumption were not evaluated, and only healthy participants were studied. Further studies are needed to evaluate all of the ingredients contained in energy drinks to determine if certain ones or a combination of those with caffeine may potentially cause cardiovascular adverse effects.2

Health care professionals can play an important role in counseling patients about the dangers of energy drinks. Individuals taking medications associated with QT prolongation such as certain antiarrhythmics, antibiotics, antidepressants, and antipsychotics, should avoid consuming energy drinks. Also, patients with hypertension should avoid energy drinks.

Health care providers can inquire about energy drink consumption during consults when discussing OTC and dietary supplement products. 

  1. Energy drinks.  NIH website.  Last updated July 26, 2018.  Accessed May 31, 2019.
  2. Shah SA, Szeto AH, Farewell R, et al.  Impact of high volume energy drink consumption on electrocardiographic and blood pressure parameters:  a randomized trial.  J Am Heart Assoc.  2019; 8(11):e011318. doi: 10.1161/JAHA.118.011318.

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