5-hour energy: Does it work? Is it safe?

5-hour energy, a popular energy drink you may have tried, makes claims that seem too good to be true… Get immediate energy that lasts for 5 hours, without a sugar crash afterwards and with the same amount of caffeine that is in one cup of coffee [1]. Are these claims true?

What’s in 5-hour energy? Caffeine, B vitamins, a sugar substitute and some other stuff.

  • Plenty of caffeine: Despite the claims on the label, some independent laboratory tests have shown that 5-hour energy contains up to 200mg of caffeine while an average cup of coffee contains just 130mg [2]. While caffeine is generally safe (even when consumed daily) there is also scientific consensus that it affects your sleep pattern, and may cause you to be more anxious, especially if you already experience anxiety [3].
  • Extremely large amounts of B vitamins (8333% of the daily value for one B vitamin): While a few recent studies have suggested that taking a daily multivitamin (with B vitamins, vitamin C and minerals) for 30 days leads to improved concentration and alertness, large amounts of these vitamins are not required to produce an effect [4]. All of the B vitamin levels in one 5-hour energy drink are below the maximum daily intake level, but since many students who use energy drinks tend to use more than 1 in a day, you may consume more than the recommended maximum level. If you experience hot or tingling skin and/or numbing sensations, you may have overdosed on B-vitamins. This is even more likely if you already take a multivitamin that contains B vitamins (especially B3 and B6).
  • Sugar substitute: The drink is sweetened with sucralose (otherwise known as Splenda©) to give it a sweet taste. This ingredient is buried in the ingredient list, so you may not have noticed that before. Since this drink contains no sugar, it will not produce a sugar crash common in some other drinks.
  • Other stuff: A mixture of several metabolic byproducts and amino acids such as phenylalanine, tyrosine and citicoline (a derivative of choline) which the company calls an “energy blend.” These components are all associated with energy and metabolism in the body. Because these compounds occur abundantly in beans, meats and many processed foods, deficiency is uncommon and there is zero evidence that consuming these compounds can improve alertness or cognitive performance unless a person has a severe deficiency [5].

The active ingredient in 5-hour energy is caffeine, plain and simple. Caffeine reduces sleepiness, enhances alertness and restores cognitive function lost due to lack of sleep [6]. The B vitamins might also help improve concentration and alertness, but these effects have only been researched in the context of daily multivitamin use and the amounts provided in 5-hour energy are much higher than needed. None of the other ingredients appear to have any effect on energy or alertness except in rare cases of deficiency or nutrient depletion, and there is no scientific basis for the claim that the increased energy will last longer than it would for a similar amount of caffeine consumed in a different beverage.

What’s the bottom line?

  • 5-hour energy may contain more caffeine than advertised, but it is still probably a safe, albeit pricey, alternative to a coffee boost for those who can tolerate caffeine. Because the caffeine dose may be higher than expected and because caffeine overdose can be dangerous, don’t try to consume more than one drink at a time.
  • If you already take a multivitamin that contains niacin (B3) or other B vitamins, be careful not to overdose by combining it with 5 hour energy.

Lastly, don’t underestimate the value of sleep. As I mentioned above, some research suggests that caffeine does not improve cognitive function, but instead simply restores cognitive function lost due to lack of sleep. Instead of spending $3-4 a pop on what is essentially a caffeine shot, you might try saving your money, and improving your energy and concentration the natural way.



  1. 5-hour Energy Ingredients and Safety. http://www.5hourenergy.com/ingredients.asp
  2. Perks of 5-hour Energy Put to the Test. CBS News. http://www.cbsnews.com/stories/2011/02/07/earlyshow/health/main7326410.shtml
  3. Broderick P, Benjamin AB. Caffeine and psychiatric symptoms: a review. J Okla State Med Assoc. 2004 Dec;97(12):538-42.
  4. David O. Kennedy, Rachel C. Veasey, Anthony W. Watson, Fiona L. Dodd, Emma K. Jones, Brian Tiplady and Crystal F. Haskell. Vitamins and psychological functioning: a mobile phone assessment of the effects of a B vitamin complex, vitamin C and minerals on cognitive performance and subjective mood and energy. Hum. Psychopharmacol Clin Exp 2011; 26: 338–347.
  5. Leyton, M; Young, SN; Pihl, RO; Etezadi, S; Lauze, C; Blier, P; Baker, GB; Benkelfat, C. Effects on mood of acute phenylalanine/tyrosine depletion in healthy women. Neuropsychopharmacology 2000; 22(1): 52-63Timothy
  6. Roehrs and Thomas Roth. Caffeine: Sleep and daytime sleepiness. Sleep Medicine Reviews (2008) 12, 153–162

3 thoughts on “5-hour energy: Does it work? Is it safe?

  1. Jim November 9, 2011 / 2:44 pm

    Very informative, thanks!


  2. Sara Stahlman November 9, 2011 / 12:58 pm

    Great info!


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