TABLE 2.

Common Ingredients, Therapeutic Uses, and Adverse Effects of Energy Drink Ingredients^{8,14,25,30,49,53,82,83}

Ingredient	Description	Therapeutic Uses	Purported Effect From Energy Drinks	Adverse Effects (due to Idiosyncratic Reaction or Excessive Dosage)
Caffeine	An adenosine receptor antagonist: a central nervous system stimulant	As caffeine citrate, used to treat apnea and bronchopulmonary dysplasia in premature infants	Increases exercise endurance and improves cognition and mood when fatigued or sleep-deprived	Nervousness, irritability, anxiety, insomnia, tachycardia, palpitations, upset stomach, vomiting, abdominal pain, rigidity, hypokalemia, altered consciousness, paralysis, hallucinations, increased intracranial pressure, cerebral edema, seizures, rhabdomyolysis, supraventricular and ventricular tachyarrhythmias
Guarana	A South American plant that contains large amounts of caffeine, theobromine, and theophylline (a chronotrope and an inotrope) and tannins	None known	Stimulant, mainly through the effects of caffeine, and weight loss	Generally considered safe by the FDA Center for Food Safety and Applied Nutrition
Taurine	An abundant amino acid in the central nervous system; acts in neural growth and protection, cell metabolism, osmoregulation, antioxidation, and glycolysis; estimated daily intake is 400 mg/d	Infant formula has been supplemented with taurine since the 1980s because of evidence that it promotes healthy development; used to treat alcohol withdrawal, congestive heart failure, cystic fibrosis, palpitations/dysrhythmias, hypertension, diabetes, seizure disorders, hepatitis	Marketed to promote eye and biliary health and to prevent congestive heart failure by lowering blood pressure while improving cardiac contractility	Generally considered safe by the FDA
l-Carnitine	An amino acid involved in β-oxidation of fatty acids	Used as a therapeutic supplement in congenital and acquired-deficiency states, end-stage renal disease, valproate toxicity, and dementia; increases attention and decreases hyperactivity in certain populations of children; nonstimulant l-acetyl-carnitine is used to treat ADHD in boys with fragile X syndrome and, in 1 study, children with typical ADHD; it may also protect against heart disease	Added to promote fat metabolism and increase endurance	In high doses, can cause nausea, vomiting, abdominal pain, and diarrhea; has been reported to cause seizures in patients with no known disease and to increase seizure frequency in patients with seizure disorder
Ginseng	An East Asian herb	Believed to improve memory, increase stamina, and stimulate immune function	Improve physical performance	Reported symptoms of ginseng toxicity include diarrhea, vaginal bleeding, headache, vertigo, mania, hypertension, rashes, insomnia, irritability, Stevens-Johnson syndrome, and agranulocytosis; some of these symptoms may be related to contaminants, such as phenylbutazone and aminopyrine, used in its processing
Yohimbine	An alkaloid found in the plants Pausinystalia yohimbe and Rauwolfia serpentina	An herbal supplement believed to be an aphrodisiac and to relieve chest pain, diabetic complications, depression, and erectile dysfunction	Increase energy, metabolism, and stamina; promotes well-being	Can cause hypertension at usual doses and hypotension at high doses; tachycardia, death