Child Psychiatry Consult

Consider caffeine effects on children and adolescents


Less clinical attention has been paid to caffeine lately as the medical community works to overcome the negative effects of substances such as opiates and cannabis. Quietly, however, caffeine continues to be widely consumed among children and adolescents, and its use often flies under the radar for pediatricians who have so many other topics to address. To help clinicians decide whether more focus on caffeine use is needed, a review was published in the Journal of the American Academy of Child & Adolescent Psychiatry (2019;58[1]:36-45). A synopsis of this paper which summarizes 90 individual studies on caffeine use in children and adolescents is provided here.

Coffee and other caffeinated beverages MonthiraYodtiwong/Thinkstock

Caffeine usage in children and adolescents

Caffeine continues to be one of the most commonly used substances in youth, with about 75% of older children and adolescents consuming it regularly, often at an average dose of about 25 mg/day for children aged 6-11 years and 50 mg/day for adolescents. Because most people have trouble quickly converting commonly used products into milligrams of caffeine, the following guide can be useful:

  • Soda (12 oz). About 40 mg caffeine.
  • Coffee (8 oz). About 100 mg caffeine.
  • Tea (8 oz). About 48 mg caffeine.
  • Energy drinks (12 oz). About 150 mg caffeine plus, with 5-Hour Energy being around 215 mg caffeine, according to a Consumer Reports study.

It is important to pay attention to the serving size, as the actual volume consumed of products like coffee or soft drinks often are much higher.

With regards to caffeine trends over time, a surprising observation is that total caffeine consumption among youth over the past decade or so looks relatively flat and may even be decreasing. This trend has occurred despite the aggressive marketing to youth of many energy drinks that contain high amounts of caffeine. In many ways, the pattern of caffeine use fits with what we know about substance use in general in adolescents, with rates dropping for many commonly used substances – with the exception of cannabis.

Effects of caffeine

As many know, caffeine is a stimulant and is known to increase arousal, alertness, and amount of motor behavior. While many youth drink caffeine in an effort to improve cognitive performance, the evidence that it does so directly is modest. There are some studies that show improvements on some cognitive tests when children take moderate doses of caffeine, but these effects tend to be most pronounced for kids who are more naive to caffeine at baseline. Of course, caffeine also can temporarily reduce feelings of fatigue and sleepiness.

Dr. David C. Rettew is a child and adolescent psychiatrist and associate professor of psychiatry and pediatrics at the University of Vermont, Burlington.

Dr. David C. Rettew

Anecdotally, many youth and parents will report that caffeine is a way to “self-medicate” various symptoms of ADHD. While many will report some benefit, there is a surprising lack of rigorous data about the effects of caffeine for youth who meet criteria for ADHD, according to this review.

There also are some well-known negative effects of caffeine use. One of the most important ones is that caffeine can interfere with sleep onset, thereby inducing a cycle that reinforces more caffeine use in the day in an effort to compensate for poor sleep at night. A less obvious negative effect that has been documented is that caffeine added to sweetened beverages can increase consumption of similar sugary foods, even if they don’t have caffeine.

A number of adverse effects have been observed when youth consume caffeine at excessive doses, which tend to be around a threshold of 400 mg/day for teens and about 100 mg/day for younger children. These can include both behavioral and nonbehavioral changes such as agitation or irritability, anxiety, heart arrhythmias, and hypertension. Concern over high caffeine intake also was raised in relation to a number of cases of sudden death, although these events fortunately are rare. The review mentions that one factor that could increase the risk of a serious medical event related to caffeine use is the presence of an underlying cardiac problem which may go undetected until a negative outcome occurs. In thinking about these risks associated with “excessive” caffeine consumption, it can be important to go back to the guides and see just how easily an adolescent can get to a level of 400 mg or more. A couple large cups of coffee per day or two to three specific “energy-boosting” products can be all that it takes.

There also are a few large longitudinal studies that have shown a significant association between increased caffeine consumption and future problems with anger, aggression, risky sexual behavior, and substance use. Energy drinks, which can deliver a lot of caffeine quickly, were singled out as particularly problematic in some of these studies, although these naturalistic studies are unable to determine causation, and it also is possible that teens who are already prone towards behavioral problems tend to consume more caffeine. However, the review also mentions animal studies that have demonstrated that caffeine may prime the brain to use other substances like amphetamines or cocaine. Finally, another concern raised about energy drinks in particular is that they also often contain other substances which may have similar physiological effects but are relatively untested when it comes to safety.


This review, like the current position of the Food and Drug Administration, considers caffeine as generally safe at low doses because there does not appear to be much evidence that low or moderate use in youth leads to significant problems. The conclusion changes, however, with higher levels of consumption, as more frequent and more serious risks are encountered. The article recommends that both parents and doctors be more vigilant in monitoring the amount of caffeine that a child consumes as well as the timing of that use during the day. Some quick calculations can be done to give adolescents and their parents an estimate of their caffeine use in milligrams. And while caffeine may not rise to the level of public health concern as substances like opiates or alcohol, there is evidence that it can cause some real problems in children and teens, especially in higher amounts, and thus shouldn’t be given a total pass by parents and doctors alike.

Dr. Rettew is a child and adolescent psychiatrist and associate professor of psychiatry and pediatrics at the University of Vermont, Burlington. Email him at Follow him on Twitter @PediPsych. Looking for more mental health training? Attend the 13th annual Child Psychiatry in Primary Care conference in Burlington, Vt., May 3, 2019 (

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