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Dr. Alessandro Giardini
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Energy drinks are everywhere in secondary schools. Monster, Prime, Red Bull, and an expanding range of high-caffeine products have become part of the daily routine for many teenagers, and parents often tell me they had no idea how much caffeine their child was consuming until an episode of racing heart brought the question into sharp focus. The good news is that most children who experience palpitations after energy drinks do not have an underlying heart condition. Understanding why these drinks affect the heart, and knowing when symptoms need proper review, makes an enormous difference to how families manage the situation.
Caffeine is the main culprit. It stimulates the nervous system, raises heart rate, and increases the force of each heartbeat. A single 500ml can of Monster or Red Bull contains roughly 160mg of caffeine. That is the equivalent of almost two strong coffees consumed in minutes.
Teenagers metabolise caffeine less predictably than adults. Body weight, individual sensitivity, hydration status, and whether the drink is consumed alongside exercise all affect how strongly the heart responds. Some young people notice nothing at all. Others feel their heart race, flutter, or thump uncomfortably after a single can.
Energy drinks compound the problem beyond caffeine alone. Taurine, guarana, and high sugar content can amplify stimulant effects. Pre-workout powders, increasingly popular in gym-going teenagers, are a particular concern: some contain 200mg to 400mg of caffeine per serving. In clinic, I see teenagers who have consumed two or three servings before a training session, well beyond any safe threshold for a child or adolescent.
Dehydration worsens everything. Many teenagers are not well hydrated to begin with, and caffeinated drinks have a mild diuretic effect. A dehydrated heart is a more irritable heart.
Most caffeine-related palpitations are benign. They feel like extra beats, a racing heart, or a brief flutter. The heart rate rises, the teenager notices it, and within minutes to an hour it settles.
This pattern differs from the sudden onset, very fast, abruptly stopping rhythm that characterises supraventricular tachycardia. It also differs from a racing heart accompanied by dizziness, near-fainting, or chest pain. The distinction matters enormously when deciding whether investigation is needed.
That said, caffeine can unmask underlying rhythm problems in some children. In a teenager with an accessory electrical pathway, a structural variation present from birth, caffeine may trigger an episode of SVT that would not otherwise have occurred at that time. Worth knowing. The energy drink did not cause the condition, but it pulled the trigger.
A single episode of a racing heart after a large energy drink, in an otherwise well teenager with no relevant family history, is unlikely to need specialist review. Stopping the drink and monitoring the situation is entirely reasonable.
Several patterns change that calculation significantly. As a paediatric cardiologist, I recommend assessment when palpitations after energy drinks are accompanied by dizziness, near-fainting, or fainting. Any teenager who loses consciousness, even briefly, during or after an episode needs proper evaluation. Similarly, palpitations that start suddenly, feel very fast, and stop abruptly rather than gradually winding down are worth investigating, regardless of caffeine involvement.
Family history carries real weight here. A parent or sibling with a known arrhythmia syndrome, hypertrophic cardiomyopathy, or unexplained sudden death before age 50 means caffeine-triggered palpitations deserve more attention, not less. I assess children in exactly this situation regularly in my London clinics, and in most cases the news is reassuring, but the reassurance is only meaningful after a proper look.
Teenagers using pre-workout supplements alongside energy drinks, particularly before intense exercise, sit in a higher-concern group and should be seen.
The simplest intervention is also the most effective. Remove the energy drink. That single change resolves palpitations in the majority of cases where caffeine is the cause.
Encouraging good hydration with water, adequate sleep, and regular meals reduces baseline heart irritability. Many teenagers experience palpitations most acutely when they are tired, skipping meals, and reaching for an energy drink to compensate. Breaking that cycle makes a genuine difference.
It is worth having a direct conversation with your teenager rather than simply banning drinks. Understanding why caffeine affects the heart, and what the symptoms mean, gives teenagers the tools to make better decisions themselves. That tends to work better than prohibition alone, particularly with older adolescents.
If symptoms continue after removing energy drinks, a review with a paediatric cardiologist is the right next step. A careful history and ECG usually provide clarity quickly.
Caffeine can trigger SVT episodes in children who have an underlying accessory pathway. The energy drink does not create the condition, but it can provoke an episode. Assessment clarifies whether an underlying cause is present.
Most guidelines suggest a maximum of 100mg of caffeine daily for adolescents. A single standard energy drink often exceeds that. Many teenagers consume multiple cans across a day without realising how far over that threshold they have gone.
Not necessarily. A single brief episode in an otherwise well teenager with no relevant family history can be managed by stopping the drink and monitoring. If episodes recur, symptoms are accompanied by dizziness or fainting, or there is a worrying family history, specialist review adds real value.
The caffeine content in pre-workout products can be considerably higher. Some formulations contain two to four times the caffeine of a standard energy drink. Combined with intense exercise, that represents a significant cardiac stimulus and warrants more caution.
A normal ECG is reassuring but does not capture intermittent rhythm problems. If palpitations recur or the pattern is concerning, ambulatory monitoring (a Holter ECG monitor) )over a longer period gives a more complete picture.
Author: Dr. Alessandro Giardini, MD, PhD
Written 22/05/2026