A cup of coffee — and the exhilarating first hit of caffeine it brings — is the sole reason some people drag themselves out of bed in the morning.But at what point should we cap our consumption, and how much caffeine is too much caffeine? That’s what we — Raj Punjabi-Johnson and Noah Michelson, the co-hosts of HuffPost’s “Am I Doing It Wrong?” podcast — recently asked Marilyn Cornelis, Ph.D., associate professor of preventive medicine at Northwestern University’s Feinberg School of Medicine.Click here to listen to the full episode and enter a world of wonder about caffeine and how it affects us.“Up to 400 milligrams of caffeine is safe, and that’s equivalent to around four cups of coffee per day,” Cornelis told us. If you prefer sodas or energy drinks, that’s about nine 12-ounce cans of Diet Coke or five 8.4-ounce cans of Red Bull.But even up to five cups a day may be safe for many people, a U.S government panel proclaimed in 2015 — and possibly even be good for their health. “It’s safe and possibly beneficial,” Cornelis said, but added, “it wasn’t a recommendation that you should be consuming five cups per day. If you’re already consuming five cups per day and you’re healthy relatively, there’s no need to cut back.”However, too much caffeine can cause a variety of unwanted issues, from headaches to trouble sleeping to anxiety. “I had a friend in college and she had never drank coffee before she got to college, and she started to love it,” Michelson said. “At the same time, she started to get sick and she couldn’t sleep and she’s losing a ton of weight. And she went to the doctor and they asked her ... ‘Are you drinking coffee?’ And she said, ‘Yes.’ And they said, ‘How much?’ And she said, ‘Well, two a day.’ And they were like, ‘That shouldn’t be it,’ so she left. After a couple of months, she came back because she was still really having a lot of issues. And they said, ‘Are you sure you’re only drinking two cups a day?’ And she said, ‘Two cups? I’m drinking two pots.’ And [her doctors] were like, ‘Oh, my God. You can’t drink two pots a day!’”Cornelis noted that we should be paying attention to not just how much we’re having a day, but also how much we’re consuming at one time. She warned that some popular beverages might even be dangerous because people are not aware of the high levels of caffeine they contain. One young woman with a heart condition allegedly died in 2022 after drinking a Charged Lemonade from Panera. Her family claimed that the large drink, which had 390 milligrams of caffeine in it — as much as four cups of coffee — caused her to experience cardiac arrest. Another customer’s family filed a lawsuit claiming he died after drinking three servings of Charged Lemonade from the restaurant. Panera removed the beverage from their menu in 2024.Cornelis told us that other energy drinks, like the popular Celsius beverages, can contain 200 mg of caffeine or more in a can.“Because [these drinks are] cold, you can down a lot in a short amount of time,” she explained. “When I’m talking about five cups of coffee per day, that’s not typically in one setting.” Michelson added, “If you have five cups of coffee throughout the day, you’re working, it’s spread out over 10 hours — that’s very different than chugging a Red Bull that tastes like soda ... or 400 milligrams in a lemonade that you might drink in eight minutes.”Ultimately, caffeine is a drug and should be enjoyed with care and consideration. It never hurts to chat with your doctor about what you’re consuming, how much, how it might interact with other drugs you’re taking, or how any health conditions you have might be affected by it.We also chatted with Cornelis about how caffeine may affect our mental health, why it might make us poop, and much more.Listen to the full episode above or wherever you get your podcasts.For more from Marilyn Cornelis, head here.Have a question or need some help with something you’ve been doing wrong? Email us at AmIDoingItWrong@HuffPost.com, and we might investigate the topic in an upcoming episode.