Caffeine Doesn't Have to Be Bad For You — Here's What to Know

Most people, myself included, start their morning with a cup of coffee. Or, more specifically, a cup of caffeine. Some folks even have a second or third cup once the clock strikes noon to power them through the rest of the day. But between sips, you may be wondering: Is caffeine bad for you?

In short, no. "Caffeine can be 'good' for you when consumed in moderation since it provides clear benefits, such as improved focus, enhanced physical performance, and potential protection against certain diseases; however, excessive intake or sensitivity can lead to negative side effects like anxiety, sleep disruption, and dependency," says Shoshana Ungerleider, MD.

But how much caffeine is necessary for you to cash in on these perks? And how much can you have before it becomes dangerous? Here's what experts have to say.

Experts Featured in This Article:

Shoshana Ungerleider, MD, is a board-certified internal medicine physician and founder of End Well Foundation.

Aderet Dana Hoch, RD, is a registered dietitian and founder of Dining with Nature.

What Is Caffeine?

Caffeine is a naturally occurring stimulant found in various plants, such as coffee beans, tea leaves (including black, green, white, and matcha tea types), and cacao pods, Dr. Ungerleider says. "In its pure form, caffeine is a white, bitter-tasting powder that acts as a central nervous system stimulant, because it works by blocking adenosine, a brain chemical that promotes sleep, resulting in increased alertness, focus, and reduced fatigue."

The stimulant is not a nutrient, so caffeine itself has no calories, fat, protein, vitamins, or minerals, Dr. Ungerleider says. Instead, the exact nutritional information of caffeine comes down to the form it's consumed in.

Coffee and tea are the most common for a caffeine fix, but it's also found in soda, energy drinks, and energy bars. Additionally, some medications and supplements, including pain relievers and cold medicines, contain caffeine since adenosine receptors are involved in pain regulation, Dr. Ungerleider says.

Is Caffeine Good For You?

When consumed in moderation, caffeine can offer several notable health benefits. One of its primary advantages is improved alertness and cognitive function, Dr. Ungerleider says. "By stimulating the central nervous system, caffeine enhances mental focus, boosts short-term alertness, and improves overall cognitive performance."

Caffeine also demonstrates neuroprotective effects, as regular coffee consumption has been linked to a reduced risk of neurodegenerative diseases such as Alzheimer's and Parkinson's disease, Dr. Ungerleider says. A 2021 study even found that higher coffee consumption was associated with slower cognitive decline in executive functioning and attention span. As for other caffeine sources, recent research shows that green and black tea consumption significantly reduces the risk of dementia.

In the same vein, moderate caffeine intake has been tied to longevity, with studies showing a correlation between coffee consumption and a lower risk of premature death. Caffeine, particularly from coffee, has also been connected to a lower risk of chronic liver disease, including liver cancer, Dr. Ungerleider adds. Plus, the antioxidants in caffeine sources like coffee and tea help protect cells from oxidative stress (a bodily condition that happens when your antioxidant levels are low), and avoiding that stress helps prevent the development of chronic disease and aging, says Aderet Dana Hoch, RD.

Caffeine may also give athletic performance a leg up by increasing adrenaline levels, which not only improve endurance but also reduce the perceived effort of exercise, Dr. Ungerleider says.

Finally, it's worth noting the source of caffeine doesn't significantly alter its effects or potential health benefits, Dr. Ungerleider says. Instead, the "best" type of caffeine comes down to the additional benefits a source has to offer. For example, green tea contains antioxidants that provide a slew of perks like improved brain function, better heart health, and reduced inflammation, whereas caffeine from soda has little nutritional value.

How Much Caffeine Should You Drink a Day?

For most healthy adults, consuming up to 400 mg of caffeine per day is considered safe, Dr. Ungerleider says. This equates to roughly four 8-ounce cups of brewed coffee, eight 8-ounce cups of tea, or two 16-ounce energy drinks, depending on the brand.

However, pregnant people should limit their caffeine intake to 200 to 300 mg per day, though you should always talk with your doctor before making any dietary changes, Hoch says. For reference, a typical 8-ounce cup of coffee contains approximately 95 mg of caffeine, while tea generally has 30 to 50 mg per 8-ounce cup.

That said, Dr. Ungerleider explains that everyone's tolerance to caffeine is different, so you should adjust your consumption accordingly, since too much can lead to unpleasant side effects.

Side Effects of Caffeine

Caffeine can have negative effects on the body, particularly when consumed in excess, with the primary issue being sleep disruption. "By blocking adenosine, a brain chemical that promotes relaxation, caffeine can delay the ability to fall asleep and reduce overall sleep quality, especially if consumed later in the day," Dr. Ungerleider says. As a result, it's best to avoid caffeine at least five hours before bed.

Another unpleasant side effect: anxiety and jitters. "Caffeine increases adrenaline levels, which can cause restlessness, heightened anxiety, and shakiness," Dr. Ungerleider explains. Some people are more sensitive to caffeine than others, but those with anxiety disorders may benefit from reducing their consumption to lessen the chance of worsened symptoms, Hoch adds.

The release of adrenaline also increases your heart rate and blood pressure, so anyone with an arrhythmia, underlying heart condition, or high blood pressure should avoid caffeine without talking to their doctor, Hoch says. In high doses, caffeine can even cause heart palpitations or irregular heart rhythms, adds Dr. Ungerleider.

"When caffeine is consumed as coffee, the acidic nature can boost stomach acid production, causing acid reflux and gastrointestinal discomfort," Hoch says. This is especially common when coffee is consumed on an empty stomach, she adds. Just note other caffeine sources like tea typically don't have this effect since they're less acidic.

You also want to make sure that you're drinking six to eight glasses of water a day (around 64 ounces) in addition to coffee or tea, since caffeine is a diuretic — it increases the production of urine and may cause dehydration, Hoch says.

Beyond that, caffeine is an addictive substance, so over time, regular use can lead to dependency and withdrawal, Dr. Ungerleider says. "Those who consume caffeine daily may experience symptoms like headaches, fatigue, and irritability when they suddenly stop or reduce their intake."

So, Is Caffeine Bad For You?

Caffeine is not inherently good or bad for you, Hoch says. "It has its benefits and risks, but like anything, caffeine should be consumed mindfully, safely, and in moderation."

Dr. Ungerleider agrees, noting that for most people, moderate caffeine consumption can be part of a healthy lifestyle — particularly when sourced from beverages like coffee and green tea. "The key is balance, awareness of individual tolerance, and mindful consumption."

Andi Breitowich is a Chicago-based freelance writer and graduate from Emory University and Northwestern University's Medill School of Journalism. Her work has appeared in PS, Women's Health, Cosmopolitan, and elsewhere.