Are any toxic effects associated with the caffeine contained in energy drinks?—L.H., ME.
Mark M. McGraw, BSN, RN, CCRN, CEN, CTRN, replies: Energy drinks sold over the counter contain high levels of caffeine and other additives, including amino acids, ginseng, B vitamins, niacin, and guarana, purported to boost energy and mental performance.1 The hidden danger of energy drinks is that their high levels of caffeine sometimes aren't accurately reported on the label. Because energy drinks are considered dietary supplements or foods, the FDA doesn't regulate their caffeine levels.2 (See Drug News, “Dietary Supplements: Wake Up to Hidden Sources of Caffeine” on page 14.)
From 30% to 50% of children, adolescents, and young adults have consumed energy drinks.3 ED visits involving adverse reactions to energy drinks more than doubled from 6,996 visits in 2007 to 14,042 visits in 2011.3
A caffeine intake of less than 400 mg/day, or about two or three cups of coffee, is generally considered safe.4 Initial signs and symptoms, such as anxiety, nervousness, or palpitations, are associated with consumption of between 4 and 12 mg/kg/day of caffeine. Signs and symptoms of toxicity, such as extreme hypertension, develop after consumption of about 1 g. A lethal dose is between 5 and 10 g.4 , 5
Some over-the-counter energy drinks contain caffeine levels up to 500 mg per 20 oz (600 mL) serving, which is 15 times the amount of caffeine found in a 12-ounce (360 mL) serving of cola.6
Some energy drinks contain guarana. The guarana plant contains the highest levels of caffeine of any plant in the world.1 In beverages containing guarana, the true level of caffeine is probably much higher than reported on the label.
The toxicity associated with energy drinks stems from the synergistic effects of the additives along with frequent consumption and lack of adequate health warnings. The excessive levels of caffeine found in these drinks predispose users to a higher rate of anxiety and panic disorders, depression, antisocial behavior, and substance abuse, according to results of a study of over 3,600 adult twins.7
Signs and symptoms of caffeine poisoning are consistent with sympathomimetic toxicity, similar to those associated with cocaine ingestion. Some of the earliest signs and symptoms of excessive caffeine intake are anxiety, nervousness, irritability, tremors, palpitations, tachycardia, and dyspepsia.
Caffeine is also arrhythmogenic when consumed in excess.1 Atrial fibrillation, atrial flutter, and supraventricular tachycardia have all been reported after the consumption of these beverages.1 Toxic levels of caffeine can cause sudden death or life-threatening conditions, such as acute kidney injury, hepatitis, seizure, stroke, coronary artery spasms, and myocardial infarction.4
The levels of caffeine in these beverages should raise a red flag for anyone needing a “pick me up.” Many of us would never consider drinking 4 to 6 cups of coffee all at once because of how it would make us feel: jittery, nervous, and on edge. Energy drinks contain just as much caffeine, if not more, in less volume, making them a deceptively simple and convenient refreshment. Teach your patients about the dangers of energy drinks and advise them to use them only in moderation or avoid them altogether.
1. Wolk BJ, Ganetsky M, Babu KM.Toxicity of energy drinks. Curr Opin Pediatr. 2012;24(2):243–251.
4. Seifert SM, Schaechter JL, Hershorin ER, Lepshultz SE.Health effects of energy drinks on children, adolescents, and young adults. Pediatrics. 2011;127(3):511–528.
6. Reissig CJ, Strain EC, Griffiths RR.Caffeinated energy drinks—a growing problem. Drug Alcohol Depend. 2009;99(1-3):1–10.
7. Kabagambe EK, Wellons MF.Benefits and risks of caffeine and caffeinated beverages. UpToDate. 2011. http://www.uptodate.com