In moderate amounts -- think 200 to 300 milligrams a day, about the equivalent to two to four cups of coffee -- caffeine is safe for most people.
At this amount, caffeine from the right source can even boast some health benefits, like improved alertness. A little caffeine pre-workout can also improve an athlete's speed and endurance, as well as make the workout seem easier, according to Men's Health.
But there is such a thing as too much caffeine. Most obviously, it messes with your sleep. HuffPost blogger and sleep specialist Dr. Michael J. Breus advises steering clear eight hours before bedtime to make sure that afternoon pick-me-up doesn't become an all-night keep-me-up.
Consuming too much caffeine may also lead to feelings of restlessness and irritability, as well as an increased heart rate, upset stomach or muscle twitches, reports Mayo Clinic. It can also contribute to osteoporosis risk and may affect high blood pressure, Karen Collins, R.D. writes for MSNBC.
While the FDA regulates caffeine content in soda -- the limit is 71mg per 12 ounces -- energy drinks have gone largely unregulated since taking the beverage market by storm. Many brands contain even higher levels of caffeine than the average consumer might be aware of, when servings per can or bottle are taken into account. Keep in mind many of these drinks are also high in empty calories or made with artificial sweeteners, both of which have been linked to weight gain.
Caffeine amounts aren't listed on nutrition labels but it must still be listed as an ingredient, according to the FDA's website. Many brands do publicize the caffeine content of their products on their websites however. Click through the slideshow to see how some of the most popular drinks measure up.
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