Perhaps your child, like mine, is mildly obsessed with coffee: coffee drinks, coffee ice cream, coffee-flavored confections. When D was younger and asked for tastes of coffee—something I drink occasionally—I told her, “The caffeine will stunt your growth, and you need all the help you can get.” (We’re not the tallest family.) As D entered tweendom, however, she no longer took this explanation at face value and started asking questions.

I actually wasn’t sure if that claim about caffeine stunting growth was true or just an old wives’ tale, so I promised D I’d do some research and get back to her on the issue. In fact, a few of the sources I found made it clear from the start that caffeine does not stunt growth, but the more I learned about its effects, the more accurate that old claim seemed to me.

Caffeine is a natural stimulant, classified as a drug, and logically it can affect kids in the same way it affects adults. But because the impact depends on body weight, the effects are more acute for kids since they are generally lighter than adults. Whether consumed in coffee, tea, energy drinks, soda, or chocolate, caffeine can cause symptoms like hyperactivity, problems concentrating, nervousness, anxiety, headaches, and stomach irritation.

A 2014 study in the medical journal Pediatrics on boys and girls from 8 to 9 and from 15 to 17 showed that caffeine—less than what you’d find in a can of soda or a cup of coffee—increased children’s blood pressure and decreased their heart rate; the body lowers the heart rate to make up for the higher blood pressure, but at higher doses, caffeine also speeds up the heart. While not a lot of data currently exists on the long-term effects for kids of repeated exposure to caffeine on the cardiovascular system, it can exacerbate heart problems and nervous disorders, which kids may not even know they’re at risk for. Dr. Steven Lipshultz, chief pediatrician at Children’s Hospital of Michigan, warns that at “high doses caffeine can bump blood pressure into the danger zone and spark life-threatening heart arrhythmias.”

Besides the possibility of leading to a dramatic health issue as in the example above, caffeine can affect children’s overall well-being and growth in a number of ways. First, kids and teens need a lot of sleep. According to WebMD.com, 7 to 12 year olds require 10 to 11 hours and 12 to 18 year olds require 8 to 9 hours of sleep per day. Too little sleep can lead to diabetes, heart disease, and obesity. Sleep boosts the immune system and the ability to learn, and it’s also primarily when the body releases growth hormone. Caffeine can last in the body for up to 8 hours, according to livestrong.com, so a kid who is trying to boost her energy level in the afternoon with a caffeinated drink may feel the effects of caffeine well into the night, which can perpetuate a cycle of insomnia.

In addition, caffeine suppresses appetite, and when kids aren’t eating enough protein, whole grains, vegetables, and fruits, their overall nutrition decreases. The body also needs adequate water to function, and when kids substitute caffeinated drinks for water, it can lead to dehydration. On top of that, caffeine is a diuretic, causing increased urination, which can also contribute to dehydration.

Increased urination also causes a loss of calcium, a mineral essential for kids’ growing bones. Plus caffeine actually interferes with calcium absorption. According to livestrong.com, every 100 milligrams of caffeine (way less than what’s in an 8-ounce medium roast coffee at Starbucks, for example) causes a loss of 5 milligrams of calcium.

As if these issues weren’t enough to steer kids away from coffee, the acidity in coffee can weaken the teeth, leading to a loss of enamel and to cavities. Note that it takes years for the enamel in new adult teeth to fully harden, which is why kids are more susceptible to cavities.

What really worries experts these days, though, is the growing popularity of energy drinks and fancy coffee concoctions. These come with tons of empty calories and loads of sugar, contributing even more to poor nutrition. Excess sugar has now been linked to everything from obesity, inflammation, diabetes, and heart disease to dementia and certain forms of cancer, according to the AARP. The American Heart Association recommends limiting sugar for kids under 18 to less than 25 grams per day. But a 12-ounce (tall) mocha Frappuccino, for example, contains 42 grams of sugar and an 8.4-ounce Red Bull has 27 grams of sugar.

After reading to this point, I can picture D asking with exasperation, “OK, so when exactly can I drink coffee?” (She claims that she is not even interested in energy drinks or froufrou coffee drinks.) The U.S. government has not set guidelines for safe levels of caffeine for kids, but the American Academy of Pediatrics recommends no food or drinks with caffeine for kids under 12. So it’s disturbing that a 2014 study in Pediatrics revealed that about 74 percent of children from 6 to 11 consume some caffeine each day. Canada does offer guidelines for safe caffeine consumption for kids based on average weights, recommending a limit of 62.8 milligrams for 7 to 9 year olds and 85 milligrams for 10 to 12 year olds, for example. Note that an 8-ounce (short) medium roast coffee at Starbucks averages around 170 milligrams of caffeine.

Considering the potential effects of caffeine on kids’ bone development, appetite, and sleep, however, I’ll keep coffee off the menu until D is done growing. This doesn’t mean she’ll never have chocolate or coffee ice cream or black tea, but since caffeine is addictive—with withdrawal symptoms that include headache, irritability, and lethargy—it doesn’t make sense to me to introduce coffee to an adolescent. And perhaps as important, the loads of sugar that come with coffee drinks, energy drinks, and sodas are not something any kid needs in her diet.

Caffeine Chart

Item	Size	Caffeine
Hershey's milk chocolate bar*	1.6 oz	9 mg
Starbucks' hot chocolate	12 oz	20 mg
Haagen Daz coffee ice cream	4 oz	29 mg
Green tea (brewed)*	8 oz	29 mg
Coke	12 oz	34 mg
Black English breakfast tea (brewed)	8 oz	40+ mg
Red Bull	8.4 oz	80 mg
Starbucks' mocha frappuccino	12 oz	75 mg
Starbucks' medium roast coffee	12 oz	235 mg

The amount of caffeine in these examples is approximate. Data is from company websites, except for items marked with an asterisk, which are from the Center for Science in the Public Interest website.