This story was updated on Dec. 7, 2023.

Many people kick off their day with a large cup of coffee or two, but the amount of caffeine actually coming in these drinks is not so clear-cut.

The U.S. Food and Drug Administration says the average adult can safely consume 400 milligrams of caffeine a day — the equivalent of four or five cups of coffee. But the amount of caffeine can vary from drink to drink. Sometimes a large coffee or energy drink can contain nearly as much as the FDA’s recommended daily amount, posing serious health concerns.

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The parents of 21-year-old Sarah Katz recently filed a lawsuit against Panera Bread after Katz, who had a cardiac arrhythmia that made her sensitive to caffeine, consumed one of their “Charged Lemonades.” These energy drinks contain up to 390 milligrams of caffeine, according to Panera’s website. In contrast, Red Bull says one of their 8.4 fluid ounce cans has 80 milligrams of caffeine.

Katz’s heart condition meant she had to limit her caffeine intake. However, the lawsuit alleges that Panera did not adequately label the beverage as an energy drink, according to CNN. The news outlet reported that as a result, Katz went into cardiac arrest after drinking a Charged Lemonade and subsequently died. 

If you called it ‘Monster drink lemonade’ or ‘energy drink lemonade,’ it would be more clear that there’s potential for it to have the contents of an energy drink in it. But charged lemonade does not … communicate necessarily that there’s that much caffeine in it.

Darin Detwiler, a food safety expert and associate teaching professor at Northeastern

On Dec. 4, a second lawsuit was filed against the restaurant chain. NBC News reported that the family of Dennis Brown filed a lawsuit saying the Florida man—who had high blood pressure, a chromosomal deficiency disorder, a developmental delay, and a mild intellectual disability—died of a cardiac arrest after drinking three Charged Lemonades.

Caffeine is a stimulant, says Adam Woolley, a clinical professor and director of assessment at the School of Pharmacy and Pharmaceutical Sciences at Northeastern University, meaning people can get addicted to it and experience side effects.

“The average healthy person can be pretty confident in taking caffeine safely in reasonable doses,” he says. “We can’t say caffeine’s going to do this or that. … It’s really on an individual basis.”

Woolley recommends that people be mindful about the caffeine content in the beverages they drink and their own reaction.

“You go to Dunkin’ Donuts or Starbucks and get a grande or (large) and those are (equivalent to) more than one cup of coffee,” Woolley says. “You’re looking at two or three there. … A cup of coffee is usually 8 ounces (or) 240 milliliters. That’s approximately half of one of those Poland Spring water bottles somebody might purchase. That’s a cup of coffee.” 

About a week after the Katz’s suit was filed, Panera reportedly added “enhanced” disclosures around the beverage, stating it should be consumed in moderation and that it’s not recommended for people sensitive to caffeine, as well as pregnant or nursing women. 

The suit itself might come down to language, according to Darin Detwiler, a food safety expert and associate teaching professor at Northeastern. In this case, Detwiler says calling a drink “charged” may not be considered a strong enough indicator that this is a highly-caffeinated beverage. 

“If you called it ‘Monster drink lemonade’ or ‘energy drink lemonade,’ it would be more clear that there’s potential for it to have the contents of an energy drink in it. But charged lemonade does not … communicate necessarily that there’s that much caffeine in it,” Detwiler says. “In the court of law, it comes down to the average American adult. Would the average American adult assume that Panera is selling you a lemonade that could have that much caffeine in it? I would be willing to imagine the answer is no.”

The company’s website advertised the Charged Lemonades as caffeinated, but compared them to their dark roast coffee so far as caffeine content. Detwiler says that may not be enough for consumers to truly make an informed decision as that label doesn’t specify it could be the equivalent of several cups of coffee.

“Without proper communication of this amount of caffeine, they essentially (robbed) Katz of her ability to make an informed decision,” he says. 

While Katz’s situation is an extreme example of sensitivity, caffeine is a stimulant and affects each individual differently, Woolley says. Factors like genetics and body weight can affect a person’s reaction to caffeine.

While caffeine can make people feel more awake and focused, it can also lead to increased heart rate, tremors, upset stomach, trouble sleeping and anxiety, Woolley added. Increased heart rate and palpitations from caffeine can be problematic for people with underlying heart conditions.

Erin Kayata is a Northeastern Global News reporter. Email her at e.kayata@northeastern.edu. Follow her on X/Twitter @erin_kayata.