How much coffee is too much? Experts weigh in

When I was growing up, my grandparents had a small farm in the mountains of Puerto Rico. We called it the campo – the countryside – and I loved roaming around on visits, plucking whatever was ripe right from the vine. There were mangos, guavas, avocados, and more, but the crop that mesmerised me most was the coffee, which my grandfather would dry and roast right in the front yard. This coffee was unlike any I had tasted before: smoky and sweet, with a deep chocolate note. It was also much stronger than the coffee back home. “Just a little bit, chica,” my mother would advise. She warned that drinking more than one cup could induce temporary delirium, even in grown men. This seemed like a stretch – but it was enough to instill a lingering awe.

It’s no secret that too much coffee, campo grown or not, really can have unpleasant side effects. “Consuming excessive coffee or caffeine can lead to anxiety, insomnia, gastrointestinal problems, tremors, or jitteriness,” says Michael Hartman, PhD, a nutrition scientist and human-performance expert. Side effects can also include heart palpitations or irregular heart rhythms. And it turns out my mother might not have been exaggerating the trippy power of my grandfather’s infamous coffee: A clinical study suggests that overdoing it on caffeine can induce hallucinations, paranoia, and delusions in otherwise healthy individuals – although it’s worth noting that some scientists dispute these occurrences as mere coincidence.

Regardless, coffee definitely has two very distinct qualities—it can either inspire pleasure or inflict pain. But where’s the line? How much coffee is actually too much?

“High-quality coffee can provide a boost in nutrients, particularly from an antioxidant standpoint,” says Kylene Bogden, a registered dietitian nutritionist. Those antioxidants may lower the risks of disease, particularly type 2 diabetes, cardiovascular conditions, and even some cancers. Plus, coffee also contains bioactive components – like chlorogenic acids, polyphenols, and caffeine – which can impact the body’s metabolic health for the better. “Chlorogenic acids can lower blood glucose levels by inhibiting glucose production and absorption in the intestines,” explains Dr. Hartman, who adds that “caffeine can enhance resting metabolism and fat burning, potentially helping to prevent weight gain.” There are even potential benefits for the brain: Studies suggest that coffee’s polyphenols may have neuroprotective properties, which could guard against neurodegenerative diseases by reducing oxidative stress.

And let’s not forget that drinking coffee can also be one of life’s great delights. “Many of us love coffee for its intoxicating aroma or because it’s a sensual ritual that gets us up and out every day,” Dr. Hartman says. Those aren’t small things, either: Scientists say that participating in daily rituals – like drinking a morning cappuccino while journaling, perhaps – can soothe uncertainty and anxiety. Other studies have found that merely inhaling coffee’s distinct aroma can inspire feelings of joy, alertness, and positivity. “Regular coffee consumption may indeed offer health benefits,” says Dr. Hartman.

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Still, there is a limit. According to the Food and Drug Administration, that limit is 400 mg of coffee – around four to five 8-ounce cups of brewed coffee. That’s the maximum recommended amount of coffee anyone should consume in a day to avoid adverse effects – but it’s not definitive: The right amount of coffee for you depends on your individual metabolic rate, overall health, and sensitivity to caffeine. “It really differs from person to person,” Bodgen explains. “Not everyone can effectively digest and metabolise caffeine.”

If you’re someone who generally has trouble falling asleep or staying asleep, you may want to avoid caffeine and other stimulants altogether – or, at the very least, stick to drinking coffee early in the day. Studies have found that consuming even small amounts of caffeine up to six hours before bed can have a significant impact on your ability to fall asleep and contribute to insomnia. “Individuals who experience sleep disturbances or are pregnant may want to limit their coffee consumption,” Hartman says. The same goes for those who have heart concerns or nutritional deficiencies: “Ingesting more than four to five cups daily, which equates to over 500 to 600 mg of caffeine, could elevate the risk of cardiovascular issues, particularly high blood pressure,” Dr. Hartman warns. “There’s also concern that higher coffee intake may amplify the likelihood of bone fractures – especially if calcium intake is insufficient.”

Even if you’re otherwise healthy, there’s still reason to proceed with caution. As mentioned above, the side effects of too much coffee include everything from increased anxiety to changes in bowel function to the jitters, so it’s definitely a good idea to be aware of your personal limit. For me, two cups of coffee is the absolute max – anything more than that makes me edgy, fidgety, and nauseous. “That wired feeling is typically caused by inflammation,” Dr. Hartman explains. “It’s from a spike in cortisol and insulin that can last up to 24 hours.” A full day of extra inflammation, a known accelerator to ageing and other health risks? That’s enough to encourage you to give that casual afternoon coffee break a second thought. Or, at the very least, inspire you to replace some of your coffee intake with a nice herbal tea.

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If you do accidentally end up overdoing it on cappuccinos, espresso, and lattes – or black tea, matcha, and energy drinks, all of which also contain caffeine – there’s hope. Yes, it might take up to 24 hours for your cortisol and insulin to stabilise, but it’s also likely that you’ll start to feel better within four to six hours. To ensure that happens, flush your system by drinking plenty of water, and if you’re experiencing an upset stomach—or, worse, overstimulated bowels – you can increase hydration and counteract coffee’s well-known diuretic effects by sipping beverages that contain electrolytes, like coconut water. Just be sure you’re not inadvertently adding more caffeine to the mix: Protein bars, chocolate, and even some cereals can contain sneaky-high levels of the stuff, so take a second to check the labels on your snacks – or, better yet, stick to fruits and veggies, which also have a hydrating effect.

To calm a caffeine-induced frenzy, you can also try some tried-and-true mindfulness techniques, like deep breathing, meditation, and visualisation – all of which have been proven to soothe the nervous system, relieve anxiety, and quell insomnia. And don’t neglect the healing powers of taking a good old-fashioned walk. Just remember to keep it mellow – the point is to slow your heart rate down and relax, not amp yourself up further. Stroll where you can be surrounded by trees, plants, or water – spending time in nature has been scientifically proven to lower cortisol levels and blood pressure, reduce flight-or-fight instincts, slow the heart rate, improve mood, and reduce anxiety.

When you do finally recover, it’s also worth remembering my mother’s advice the next time you’re pouring yourself a cup: “just a little bit.” Moderation is always a good policy when it comes to anything that can induce pleasure or pain – coffee included.