You probably have heard that the FDA warned of the possible involvement of three brands of energy drinks—5-Hour Energy, Monster Energy and Rockstar Energy—in 13 deaths in four years. We’re not talking about uncomfortable side effects here—we’re talking about deaths.

Now, it’s not yet known whether these drinks caused the deaths, and if they did, it’s unknown which particular ingredient(s) are to blame. But one of the main ingredients in these drinks, as we all know, is caffeine. Some people can consume lots of caffeine and experience no side effects, but others are naturally more sensitive to the substance, and the more they consume (especially within a short time frame), the more likely they are to experience side effects, including jitters, nervousness, insomnia, palpitations, heart-rhythm changes and even death from overdosing or a heart arrhythmia.

All of which makes you wonder—how much caffeine is actually in energy drinks…and are those amounts safe? The problem, which research from Consumer Reports brings to light, is that many of the companies that make energy drinks don’t list caffeine content on labels—and those that do aren’t always truthful.

WHEN LABELS LIE

Gayle Williams, deputy health editor at Consumer Reports, and her colleagues investigated 27 top-selling energy drinks and made a number of interesting discoveries. I chatted with Williams and she broke down the major findings for me…

Caffeine content varies widely. It ranged from a mere 6 milligrams (mg) per serving (ironically, for 5-Hour Energy “Decaf”) to well over 200 mg per serving. The drinks with the most caffeine per serving were:

Full Throttle (210 mg)

Celsius Your Ultimate Fitness Partner (212 mg)

5-hour Energy (215 mg)

Monster X-presso (221 mg)

NOS High Performance Energy Drink (224 mg)

Rockstar Energy Shot (229 mg)

5-hour Energy Extra Strength (242 mg).

To give you some caffeine context, an eight-ounce cup of coffee contains roughly 95 mg to 200 mg of caffeine, according to the Mayo Clinic.

Many don’t label caffeine content. More than one-third of the drinks analyzed—11, to be exact—did not list caffeine content on their nutrition labels. Why? Companies are typically reluctant to share proprietary recipes, so that may be part of the reason, but get this—there is no legal requirement to do so. I don’t know about you, but I find this unacceptable (more on that in a minute).

Many labels lie. Of the 16 drinks that did list caffeine content, researchers discovered that the information was often wrong! Five of the drinks—Arizona Energy, Clif Shot Turbo Energy Gel, Nestle Jamba, Sambazon Organic Amazon Energy and Venom Energy—contained at least 20% more caffeine than was listed on their labels. This finding also really bothers me—where do these companies get off?

You might be thinking: Well, if an eight-ounce cup of coffee has roughly 95 mg to 200 mg caffeine, and these drinks don’t have a lot more than that per serving, then what’s the big deal? The size of these energy drinks impacts the way many consumers drink them. For example, 5-Hour-Energy is about two ounces in size, so it’s only slightly larger than a shot glass (1.5 ounces). Since the containers are so small and the amounts seemingly insignificant, many people buy two or even three of them and chug them all in a row. With other energy drinks, such as Monster Energy and Rockstar Energy, the “serving size” listed on the label is eight ounces, but the cans are available in massive sizes, such as 16 ounces and 24 ounces. As a result, many people drink the entire can at once—consuming up to three servings. So in reality, some people who drink these beverages will be quickly consuming more like 400 mg to 700 mg of caffeine (possibly even more, since the caffeine content in some energy drinks is unknown)—along with all the sugar found in most of these drinks, which makes the jolt that much more powerful.

Personally, I wish that regulators would be more forceful when it comes to regulating caffeine content and labeling, especially considering that these drinks really are not thought of as drugs—even though caffeine is a drug. Plus, even though many of these drinks carry labels that say that children shouldn’t consume them, it’s all too easy for kids to get their hands on these types of beverages and ignore the caution.

I’d love to hear readers’ thoughts on whether caffeine regulations should be tougher, so feel free to leave a comment below the story.

HOW MUCH IS TOO MUCH?

The jury is still out on exactly how much caffeine is considered “safe”—what makes this a controversial topic is the fact that different people may respond to caffeine quite differently. As I mentioned earlier, some people experience side effects from consuming very small amounts of caffeine, while others don’t.

Caffeine can also exacerbate certain medical problems—for example, doctors often tell people with high blood pressure or heart disease to either avoid or at least cut back on caffeine.

So if you’re healthy and not overly sensitive to caffeine and you have one serving of an energy drink a day, it’s probably not going to cause you any harm. But if you consume multiple servings a day—especially if you experience any of the side effects mentioned above—talk to your doctor to make sure that you’re not overdoing it.

And remember that there are few (if any) nutritional benefits in consuming these types of energy drinks. If it’s caffeine that you’re after, you can get your jolt (minus all the sugar) and know exactly how much you’re getting by taking a caffeine pill…or, better yet, get some nutrients along with your caffeine by drinking coffee or tea.