The Truth About Energy Drinks

By: Erika von Vajna, PharmD Candidate

It seems like a quick fix
When we think about the upcoming semester, undoubtedly many of us think about long days and late nights at the library. Many times this is accompanied by strategies to maintain our stamina and motivation, including the use of energy drinks. It has been reported that among college-aged students, between 34% and 51% of us consume energy drinks on a regular basis. Many of us know that the main ingredient in energy drinks is caffeine, but many also contain additional stimulant drugs like taurine and guarana. Several also contain a variety of vitamins, herbal supplements, and sugar or sweeteners. Marketed benefits of energy drinks include quick onset of increased energy, concentration and focus, as well as weight loss and improved athletic performance. Energy drink companies endorse catchy slogans suggesting “hours of energy,” “giving you wings,” and “unleashing the beast.”


While all of this seems great, especially for sleep-deprived college students, it’s important to think about some of the side effects of the ingredients in these drinks that might not make them so appealing and could potentially be extremely harmful.

The Science
A recent US report found that there has been an almost doubling of energy drink-related emergency room visits between 2007 and 2011. Many of these side effects stem from the high amounts of sugar and caffeine as well as many of the other caffeine-like substances found in many of these products. Specifically, high doses of caffeine have been associated with restlessness, anxiety, irritability, trouble sleeping, headaches, dehydration and increased heart rate and palpitations. More serious adverse events that have been associated with the consumption of energy drinks include seizures, mania, stroke, and sudden death. The potentially lethal cardiac effects that have been reported were commonly associated with those patients who had underlying cardiac disease. Therefore, it is especially important for these individuals to avoid or at least limit the use of these drinks. Many of the more serious adverse effects were found at caffeine dosages greater than 400 mg per day, and consumption of 5-10 grams can be lethal.

The following shows the caffeine content (mg) for common beverages (oz):
Espresso, 1 oz, 30-90 mg
Brewed Coffee, 8 oz, 102-200 mg
Brewed Tea, 8 oz, 40-120 mg
Mountain Dew, 12 oz, 54 mg
Dr. Pepper, 12 oz, 42-44 mg
Coca Cola, 12 oz, 35-47 mg
Pepsi, 12 oz, 36-38 mg

And here is the caffeine content (mg) for common energy drinks (oz):
5-Hour Energy Shot, 2 oz, 200 mg
Full Throttle, 8 oz, 100 mg
Monster, 8 oz, 80 mg
Rockstar, 8 oz, 80 mg
Redbull, 8.3 oz, 80 mg

Many of the energy drinks we commonly use also contain a number of additional ingredients. Although not a comprehensive list, below are some of the reported side effects of those ingredients. Many of these side effects are more pronounced at higher concentrations of these ingredients and each individual will respond differently. Also, because the dosages and caffeine content of these are not required on the product labeling, it’s important to be cautious when ingesting these beverages.

Niacin (Vitamin B3): Flushing, itching, heart palpitations, insomnia, liver toxicity
Pyridoxine: Headache, nausea, tingling/numbness in arms or legs
Cyanocobalamin: Anxiety, dizziness, headache, diarrhea
Riboflavin: Discoloration of urine
Taurine: Bleeding, low blood pressure, high cholesterol
Citicoline: Nausea, diarrhea, rash, headache, insomnia
Guarana: Hear palpitations, irritability, anxiety, headache, dehydration

Regulation (or lack of)
Regulation of energy drinks differs from that of traditional caffeinated beverages, such as cola and coffee. In the United States, these products are classified as dietary supplements and as such are tested and regulated differently than conventional foods or drugs. The FDA is responsible for taking action against any unsafe dietary supplement product after it reaches the market. This means that manufacturers of these products do not necessarily need to register their products with the FDA (although they may choose to) or get FDA approval prior to producing or selling these supplements.

Because of these regulations, manufacturers also do not need to report dosages on the package labeling. This is in contrast to the manufacturing of foods and beverages. Beverages, such as Coca Cola®, are not classified as dietary supplements and therefore must be registered with the FDA and must comply with strict manufacturing requirements including proper labeling with accurate dosing. The FDA does have the authority to impose certain restrictions on beverages. For example, a 12 fl.oz. can of Coca Cola® has an FDA imposed caffeine limit of 71 mg.

Read the label
Energy drinks are consumed by millions of people worldwide and continue to be an important supplement used by many college-aged students especially around exam time. Although these drinks seem to have many beneficial effects, it is important to remember the many adverse side effects associated with their use. Always read the labeling on any product and be informed of the ingredients and potential interactions with other medications as well as their side effects and keep in mind that because they are not as strictly tested or regulated as prescription medications, dosages may vary by batch. In general, the consumption of energy drinks should be avoided if at all possible. If you’re really in need of that extra boost, try grabbing a quick nap instead!

For more on energy drinks.

1. Velazquez CE, et al. Drug Alcohol Depend. 2012 Jun 1;123(1-3):167-72
2. Seifert SM, et al. Pediatrics. 2011 March; 127(3): 511–528.
3. Harland BF. Caffeine and nutrition. Nutrition 2000; 16:522.
4. Juliano LM, Griffiths RR. Caffeine. In: Substance Abuse: A Comprehensive Textbook, Fourth Edition, Lowinson JH, Ruiz P, 
Millman RB, Langrod JG (Eds), Baltimore: Lippincott Williams, & Wilkins, 2005.
5. NaturalStandard. 2013.
6. FDA. Q&A on Dietary Supplements. 2013.
7. SAMHSA: Drug Abuse Warning Network. Update on Emergency Department Visits Involving Energy Drinks: A Continuing 
Public Health Concern. 2013 January.

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