The Dangers of Hidden Caffeine

Energy drinks have been the subject of wrongful death lawsuits. Here’s why older people are at greater risk

Kelsey Ogletree,

AARP

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Published March 12, 2025

Highly caffeinated drinks are often sold as healthy, refreshing beverages, but they can cause dangerous side effects. Older adults and those with certain health conditions face the greatest risk.

Daniel Downey

When 73-year-old Bob V.* stopped at a café near Huntsville, Alabama, he decided to try one of the orange-mango “refreshers” he’d heard people raving about. The tall drink was sweet, fizzy and refreshing on that hot July afternoon. Halfway through his cup, however, he noticed he was feeling irritable and jittery, and it only got worse from there.

“I couldn’t fall asleep the whole night,” he says. “I could have danced the Charleston at 2 a.m.”

In the United States, an 8-ounce cup of coffee delivers about 95 milligrams of caffeine. Unknowingly, Bob — who normally avoids all forms of caffeine — had downed the caffeine equivalent of nearly three cups of coffee in a matter of minutes.

The barrage of highly caffeinated drinks, often marketed as lemonade-style beverages, that have appeared on drive-through menus lately may look delicious and even seem healthy. But they can cause unwanted and even dangerous side effects for consumers unaware of what they’re drinking. In 2023, a 46-year-old man went into cardiac arrest and died after drinking a Panera Bread Charged Lemonade, which reportedly contained 390 milligrams of caffeine. In 2022, a 21-year-old with a heart condition died after downing the same drink. The chain removed the lemonade from its menu in May 2024, but other supercharged soft drinks, such as Dunkin’s Energy and Starbucks’ Iced Energy, may have more than 200 milligrams of caffeine. Many energy drink offerings at other chains, such as Scooter’s Coffee Scooot Energy, don’t publish caffeine content, making it difficult to know how much caffeine you’re drinking.

Several fast-food chains, including Taco Bell and Jack in the Box, also offer high-caffeine soft drinks. At the gas station, you might pick up a can of Rockstar Focus, Celsius Essentials, G Fuel or Bang Energy, each of which delivers 200 to 300 milligrams.

These drinks may promise a quick pick-me-up. But for older Americans and those with certain health conditions, they can present real dangers.

What is caffeine?

“To an extent, it’s the most used drug in the world,” says Amit Shah, M.D., a geriatrician with the Mayo Clinic in Scottsdale, Arizona. People wake up with a cup of coffee or tea around the world, and in general, this is safe in moderation, he says. Caffeine can also be found in many sodas, as well as hot chocolate, chocolate bars and chocolate-flavored foods.

Some studies have shown that caffeine may be beneficial to your health, too, reducing your risk of developing Parkinson’s disease, dementia and Alzheimer’s disease, among other benefits.

About 30 to 60 minutes after drinking a beverage with caffeine, you usually feel an energy boost, depending on what the drink is and how it’s prepared, Shah says. For instance, a shot of espresso or a highly concentrated energy shot like those found in gas stations will hit your bloodstream faster than a drink with added protein, such as a cappuccino.

According to the Food and Drug Administration, 400 milligrams of caffeine is considered the safe daily amount for healthy adults. It can be tricky to track exactly how much you’re ingesting, though. Caffeine content varies widely depending on how a drink is prepared, and it’s not a requirement for food or beverages to list caffeine content on labels.

Why caffeine can be problematic for older adults

As we get older, our bodies become more sensitive to the effects of caffeine. “Even smaller amounts of caffeine are not tolerated as much as we age,” says Sarah Christine Ruff, M.D., a primary care physician with UNC Health in Durham, North Carolina. This happens for a variety of reasons, including changing body composition, renal function and enzyme levels. In one study, coffee drinkers between the ages of 65 and 70 took 33 percent longer to metabolize caffeine than younger participants, meaning that the effects of the caffeine are amplified and last longer. Smoking and certain medications also increase the time needed to metabolize caffeine, says Stacey Woodson, a registered dietitian based in Philadelphia.

You know the telltale signs when you’ve had too much caffeine: irritability, feeling jittery, insomnia. Unfortunately, the only remedy is to wait it out. “You have to let your body metabolize it,” Shah says.

However, if you ingest a very high level of caffeine, have a health condition or take a medication that makes you particularly sensitive to caffeine, you may experience symptoms including a racing heart, heart palpitations, irregular heartbeats, feeling agitated and anxious to the point of wanting to crawl out of your skin, or even having a panic attack, Shah adds. If you experience these symptoms, get to a hospital.

Since caffeine decreases blood clotting, it may interact with other drugs that do the same, such as warfarin, aspirin or NSAIDs. It can also reduce the efficacy of certain drugs used to treat diabetes, depression and thyroid problems. (Ask your doctor what a safe caffeine consumption level is for you.)

Who should avoid highly caffeinated beverages?

Older adults with these specific health conditions need to be especially mindful of caffeine consumption and avoid highly caffeinated drinks.

Osteoporosis: Studies have shown that caffeine’s metabolites — what caffeine is broken down into — can cause calcium loss and increase the risk of osteoporosis. Another recent study shows that caffeine ingestion and its metabolites are associated with potential bone health issues in postmenopausal women.
Heart conditions: Anyone with heart arrhythmia, including atrial fibrillation, should avoid highly caffeinated beverages entirely, Ruff says. Both conditions can cause your heart to race, leading to severe complications and even death when exacerbated by excess amounts of caffeine.
High blood pressure: This condition becomes more common as people age, and caffeine can raise it further.
Diabetes: Anyone with diabetes should avoid highly caffeinated drinks with added sugar, Ruff says.
Sleep disturbances: Older adults are more likely to have sleep problems than the general public, and caffeine can amplify these issues by increasing the time it takes to fall asleep and decreasing the duration and quality of sleep, says Woodson.

The bottom line

If you like caffeine, stick to coffee and tea, and avoid the processed sugar and high caffeine content found in energy drinks, Ruff advises. If you feel you need an energy drink to get through the day, she adds, talk with your doctor about your sleep and other factors that may be causing you to feel tired.

*Last name withheld by request

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