Could Energy Drinks Be Bad for Your Heart?

Whether you're in an afternoon slump, have a tough workout ahead or need to be more alert than usual, sometimes you just need a pick-me-up. But if your caffeinated beverage of choice happens to be an energy drink, the promise of stamina and focus can come with some unexpected tradeoffs.

While an occasional energy drink may not be dangerous for most healthy adults, regularly consuming large amounts — or downing multiple drinks in a short period — can increase the risk of heart-related side effects.

“Caffeine is a powerful stimulant,” says Dr. Sadeer Al-Kindi, a preventive cardiologist at Houston Methodist. “In moderation, it can be safe for most people. But energy drinks often contain much higher and more concentrated doses than people realize — and that’s where problems can arise.”

How caffeine affects the heart

Caffeine is a stimulant that helps you feel more awake by blocking adenosine receptors in the brain. But it also affects the cardiovascular system.

Caffeine can temporarily:

• Increase heart rate

• Raise blood pressure

• Make the heart beat more forcefully

This can lead to noticeable symptoms, such as a racing heartbeat, palpitations or feeling jittery — the severity of which is influenced by factors such as pre-existing health conditions, the amount of caffeine consumed and the duration of exposure. Late intake of caffeine can also disrupt sleep, which can lead to many health hazards over time.

(QUIZ: Are These Afternoon & Evening Habits Ruining Your Sleep?)

"What's interesting is that, in moderate amounts, caffeinated beverages like coffee and tea may have health benefits," adds Dr. Al-Kindi. "The problem, though, is energy drinks concentrate high amounts of caffeine into a single serving, often also combining it with other stimulants."

(PODCAST: Coffee Is the World's No. 2 Beverage — But Is It Healthy?)

How much caffeine is too much?

If you're a regular energy drink drinker, do you need to cut back? Here's how to tell:

Per day

The Food and Drug Administration considers up to 400 milligrams of caffeine per day to be a generally safe upper limit for most healthy adults.

That’s roughly:

• 3-4 cups of brewed coffee

• Or one large energy drink, depending on the brand

Most energy drinks contain 200–300 milligrams of caffeine, depending on the brand and can size. And some cans include multiple servings, making it easy to exceed daily recommendations without realizing it.

Keep in mind that these limits include all sources of caffeine throughout the day — coffee, soda, tea and energy drinks combined. Drinking multiple energy drinks — or combining them with coffee or soda — can push intake well beyond safe limits without much warning.

Additionally, know that pregnant and lactating women generally have lower caffeine limits.

In a single drink

There’s no official “per-drink” caffeine limit, but Dr. Al-Kindi cautions against consuming more than 200 milligrams at once, especially in a short time frame.

"Rapid caffeine intake can spike heart rate and blood pressure," he warns. "This is especially problematic if you have an underlying heart issue, like an arrhythmia, which you may not yet know about."

Over time

Repeated high caffeine intake may lead to tolerance, dependence and withdrawal symptoms such as headaches, irritability and fatigue.

(Related: 5 Tips for Keeping a Symptom Diary for Headaches, Digestive Problems & More)

"Some studies even suggest that long-term caffeine abuse is associated with higher rates of hypertension and heart rhythm disturbances, warns Dr. Al-Kindi.

For teens and kids

The bright colors and fun flavors of energy drinks might be appealing to teens, but Dr. Al-Kindi points out that a single drink can easily exceed the amount of caffeine considered safe per day for teens, which is no more than 100 milligrams (or no more than 2.5 mg/kg of body weight per day).

Additionally, the American Academy of Pediatrics recommends that kids avoid energy drinks entirely.

“Children's hearts and nervous systems are still developing,” explains Dr. Al-Kindi. “They’re more sensitive to stimulants, and the risks of consuming caffeine far outweigh any potential benefit.”

Ingredients beyond caffeine that may affect heart health

Energy drinks rarely contain caffeine alone. Many include a blend of other stimulants and additives that can amplify cardiovascular effects:

• Guarana: A plant-based stimulant that contains caffeine. It adds to total caffeine intake but may not always be clearly quantified on labels.

• Taurine: An amino acid that can influence muscle contractions and may intensify caffeine’s effects.

• Added sugars: Large sugar loads can cause rapid spikes and crashes in blood sugar and may contribute to long-term metabolic and heart health issues.

“People assume problems only happen with caffeine,” Dr. Al-Kindi notes. “But there are a lot of unknowns surrounding the combination of stimulants found in energy drinks that make them more concerning than other caffeine sources, like coffee or tea.”

5 things to check when reading an energy drink label

Understanding what’s in your can is key to making safer choices. When reading an energy drink label, look for:

1. Total caffeine content: Check both per-serving and per-container amounts.

2. Serving size: Some cans contain two servings.

3. Hidden caffeine sources: Ingredients like guarana, yerba mate or green tea extract.

4. Sugar content: Some drinks contain more sugar than a soda.

5. Supplement classification: Products labeled as supplements may not follow the same labeling rules as beverages.

“If you don’t see a clear caffeine number, that’s a red flag,” warns Dr. Al-Kindi. “If you can’t easily tell how much you’re drinking, it’s easy to overdo it.”

Who should be especially cautious with energy drinks?

Energy drinks may pose greater risks for people who:

• Have heart disease or high blood pressure

• Have a history of arrhythmias

• Take stimulant medications

• Are pregnant or lactating

• Combine energy drinks with intense exercise or alcohol

"Especially for a person with a pre-existing cardiovascular condition or who is predisposed to arrhythmia, energy drink consumption certainly increases the risk of adverse outcomes such as arrhythmias or heart failure," says Dr. Al-Kindi.

With energy drinks, moderation matters

Energy drinks aren’t inherently dangerous for everyone — but they’re far from harmless. High caffeine levels, stimulant combinations and rapid consumption can place real strain on the heart, especially when used frequently or without awareness of total intake.

“Moderation and mindfulness matter,” says Dr. Al-Kindi. “If you need energy, start with sleep, hydration and nutrition — not a can full of stimulants.”

For most people, treating energy drinks as an occasional tool rather than a daily habit is the safest approach — and your heart will thank you.