How Much Caffeine Is Too Much Caffeine?

Most of us — 75% of us, in fact — enjoy a cup of coffee in the mornings. Some of us love the taste, others enjoy the ritual and still others just need it to wake up. For many of us (ahem, me) it’s all three.

But earlier this week, the news broke that the parents of 21-year-old college student Sarah Katz are suing the restaurant chain Panera Bread. Katz had a heart condition called Long QT syndrome type 1 , which impacts the electrical system that controls the heartbeat. She died — allegedly after drinking Panera’s caffeinated Charged Lemonade.

A regular-sized Charged Lemonade contains 260 milligrams of caffeine. But on Panera’s website , the main reference to the drink’s caffeine content says it’s equivalent to that of their dark roast coffee and that the caffeine itself is “ clean” (defined as caffeine derived from guarana or green coffee extract). To find the actual numbers, you have to scroll to the very bottom of the page.

The news has left many wondering (and worrying): How much caffeine is too much, especially if you have a heart condition? We talked to a cardiologist to find out — here’s what he had to say.

What amount of caffeine is generally considered safe?

For most people who don’t have a heart condition, caffeine consumption is considered safe up to a certain point. “According to the American Heart Association and the U.S. Food and Drug Administration, three to four cups of coffee per day has been shown to be safe for most people and not associated with adverse effects on cardiovascular health or health in general,” said Dr. James Udelson , chief of cardiology at Tufts Medical Center.

Depending on the strength of your coffee, three to four cups is typically somewhere between 300-400 milligrams of caffeine total. To hit that level, you would probably have to drink between 10 and 15 cups of green tea, or one or two energy drinks. An 8.4-ounce can of Red Bull, for example, has 80 grams of caffeine, which is about the same as a cup of coffee, but other brands may have more or less.

A 12-ounce can of Coke has less caffeine than a cup of coffee and more than a cup of green tea, at 34 milligrams . Diet Coke has more caffeine, with 46 milligrams per 12-ounce can, and the famously highly-caffeinated Mountain Dew has 54 milligrams of caffeine per 12-ounce can.

“In general, caffeinated soda and green or black tea would contain about half as much caffeine as coffee,” Udelson noted. “Energy drinks (or other drinks with added caffeine, as in this case [of the Charged Lemonade]) may have up to twice the caffeine level as a cup of coffee.”

To put Panera’s Charged Lemonade into context, a regular size has about as much caffeine as two to three cups of coffee and about 10 cups of green tea.

What are some signs that you’ve had too much caffeine?

Many of us are at least somewhat familiar with the experience of realizing we’ve overdone it on caffeine, especially if we’re the anxious type. “Signs of too much caffeine could include insomnia, jitteriness, palpitations, excessive sweating, nausea and headache,” Udelson said.

There are long-term effects of overdoing it on the caffeine, too. “Chronic use of too much caffeine could be associated with chronic sleep problems, anxiety, chronic stomach problems, high blood pressure and heart rhythm disturbances,” Udelson added.

But wait — there’s some good news!

While the effects of caffeine seem to range from annoying to life-threatening, Udelson reiterated that for most people, moderate consumption of caffeine is completely fine. In fact, it can actually be beneficial to health .

“Contemporary studies such as those from the United Kingdom’s BioBank have shown that moderate coffee consumption (two to four cups per day) can be associated with lower risks of cardiovascular diseases such as coronary artery disease, heart failure, stroke and atrial fibrillation,” he said.

So who really needs to watch their caffeine intake?

Of course, there are some people who need to be extra careful with their caffeine consumption.

“ It is recommended that pregnant and lactating people limit caffeine to the equivalent of two to three cups of coffee per day,” Udelson said. “Some heart problems, such as certain heart rhythm disturbances, may make people more susceptible to the adverse effects of caffeine on their rhythm problem.”

If your heart health is stable and you’re not pregnant or breastfeeding, try not to worry too much about your caffeine consumption. But if you’re ever concerned about how your body might react to caffeine, especially if you notice persistent issues like jitteriness or insomnia, it’s important to consult your doctor.