Can too much caffeine kill you?

According to a lawsuit filed in the Court of Common Pleas of Philadelphia County on Monday, a student at the University of Pennsylvania collapsed hours after consuming a beverage from Panera Bread called "charged lemonade" on September 10, 2022. She fell into cardiac arrest and was transported to a hospital where she went into another cardiac arrest and died.

The student, 21-year-old Sarah Katz, had a heart condition called long QT syndrome type 1, which caused an irregular heart rhythm, so she avoided energy drinks. According to the lawsuit, the charged lemonade had 390 milligrams of caffeine in it, far more than what can be found in drinks like Monster or Red Bull but was not advertised properly.

In a statement to USA TODAY, a Panera spokesperson said: “We were very saddened to learn this morning about the tragic passing of Sarah Katz, and our hearts go out to her family. At Panera, we strongly believe in transparency around our ingredients. We will work quickly to thoroughly investigate this matter.”

Here's what to know about the potential dangers of caffeine.

How much caffeine is dangerous?

One cup of coffee has about 95 milligrams of caffeine and one 12-ounce Red Bull has 111.

Registered dietician Jordan Hill previously told USA TODAY the recommended limit for caffeine intake is about 400 milligrams throughout the day. Still, Hill recommends 300 milligrams per day for adults, especially those who may be more sensitive to the side effects of caffeine.

Coffee is not the only caffeinated substance — many types of tea, soda, energy drinks or bars, supplements and even chocolate contain caffeine. 

“Each of these items have different, varying amounts of caffeine in them, so if we're consuming them throughout the day, it could be very easy to go above that 300 milligram recommendation,” Hill said.

More:Panera Bread's ‘Charged Lemonade’ being blamed for student's death, family files lawsuit

What are the side effects of caffeine?

And what happens if you go above 400 milligrams? The potential for a number of side effects, according to Hill:

• Headaches
• Insomnia
• Nervousness or anxiety
• Irritability
• Rapid heartbeat
• Muscle tremors

Long-term over consumption may exacerbate these effects, and heavy caffeine drinkers could experience high blood pressure, ongoing gastrointestinal issues and, in rare cases, death.

How much caffeine is dangerous?Here's what to know before having that next cup.

What does caffeine do to the body?

Caffeine is technically a drug; a stimulant. This means it speeds up the central nervous system and boosts energy levels. Caffeine is absorbed within 45 minutes of consuming, and stays in the blood anywhere between 90 minutes to nine and a half hours. This is also dependent on how much food is consumed, smoking (which speeds up the breakdown) or pregnancy and oral contraceptives (which slows it down). 

“We can build up a tolerance to it, which just means we require more caffeine to feel the same effects,” Hill said, pointing to short-term effects like alertness and increased productivity. “It might take more caffeine to feel those things, but at the same time, as that amount of caffeine goes up, so does the risk for side effects.”

How much caffeine can kids have?

The recommendation for kids ages 11 and younger is zero caffeine and less than 100 milligrams per day for kids ages 12 to 17, Hill said.

It’s not just coffee — parents should keep an eye out for caffeine in soda, chocolate, over-the-counter medications and even coffee-flavored foods like ice cream and candy.

The biggest worry with children and caffeine is sleep disruption.

“That's going to impact their learning abilities the following day, they're going to be sleepy, they're not going to be as alert," Hill said. "It'll interfere with regular development."

More:Do energy drinks do more harm than good?

How harmful are energy drinks?

Kelly Morrow, a registered dietitian and clinical affiliate of the Osher Center for Integrative Medicine at the University of Washington, previously told USA TODAY that she "would not recommend caffeinated energy drinks to anyone with heart disease, high blood pressure, insomnia, anxiety, depression or other mental health problems."

“Everyone breaks down the caffeine in their body at different rates," she said. "Those who drink a lot or break it down slowly may have trouble sleeping and may feel anxious. Depending on how much caffeine (energy drinks) contain – some people have had a dangerous irregular heart rhythm after drinking energy drinks."

The same goes for sugar, which is also often found in energy drinks, Clara Di Vincenzo, a registered dietitian for the Digestive Health Institute at UT Health Austin, previously told USA TODAY. Sugar, or carbohydrates, are essential for our cells to function but excess amounts can be damaging.

“With the high amounts of sugar and caffeine seen in energy drinks, we can see a blood sugar spike – which will temporarily increase energy levels, but then we’ll see a crash a couple of hours after,” Di Vincenzo said. “Not to mention some of the long-term effects of excess sugar like insulin resistance and type 2 diabetes,” she added. 

How can someone reduce their coffee consumption?

Hill offered the following tips to reduce coffee consumption:

• Switch between caffeinated and decaf coffee
• Try a half decaf-half regular coffee
• Transition to tea, which has less caffeine than a cup of coffee
• Alternate coffee with water, which may quench your thirst by hydrating rather than reaching for another cup

Contributing: Sarah Al-Arshani, Clare Mulroy, Delaney Nothaft