Caffeine is almost everywhere in our daily lives—whether it’s your morning coffee, a cup of tea, a can of cola, an energy drink, or even a piece of chocolate. It’s widely consumed and often enjoyed for its ability to make us feel more alert and awake.
But while caffeine in small to moderate amounts is generally safe, too much of it can lead to serious health problems—and in extreme cases, even be fatal.
According to biologist Dr. Anke Ehlers from Germany’s Federal Institute for Risk Assessment (BfR), moderate caffeine intake can have a stimulating, positive effect on the body and mind.
However, in higher amounts, caffeine may cause side effects like sweating, anxiety, sleep disturbances, and irregular heartbeats. For pregnant women, excessive caffeine can also affect fetal growth, and caffeine supplements in extreme doses have led to fatal outcomes.
For healthy adults, a single dose of up to 200 milligrams of caffeine is considered safe. That’s about the same as two cups of coffee, four cups of black tea, two cans of energy drink, or five cans of cola. Over the course of a day, up to 400 milligrams is generally seen as the upper limit for most adults.
However, tolerance levels vary. People who regularly consume caffeine—like daily coffee drinkers—may need more to feel the same effect, which can lead to even higher consumption. This doesn’t necessarily make it safer, and some people are more sensitive than others, experiencing negative effects at lower amounts.
Particular caution is needed when it comes to caffeine in supplement form, especially products marketed for sports performance or weight loss. These supplements can contain concentrated caffeine levels that are easy to overdose on if not taken carefully.
Dr. Ehlers especially warns against pure caffeine powder in loose form, calling it extremely risky. A safe dose of 200 milligrams equals just a pinch of this powder—something that cannot be reliably measured with a kitchen scale. Just one or two teaspoons could be lethal.
For children and teenagers, the safe amount depends on body weight. A daily dose of 3 milligrams of caffeine per kilogram of body weight is considered acceptable. For instance, a four-year-old child weighing around 17 kilograms should have no more than about 50 milligrams of caffeine per day.
This amount could be reached by consuming two and a half bars of milk chocolate or half a liter of cola. While it’s unlikely a child would consume that much caffeine all at once through sweets, the BfR warns it’s not a reason to let down your guard—especially considering the high sugar content of these products.
Teenagers are at higher risk, particularly from energy drinks. One 250 ml can of energy drink contains about 80 milligrams of caffeine—similar to a cup of coffee. Just three cans could push a teen beyond their safe caffeine limit.
The problem grows when energy drinks are mixed with alcohol, a combination that has become popular in some social settings. Both caffeine and alcohol put stress on the heart, and when used together, they may increase the risk of heart rhythm problems and other cardiovascular effects.
In summary, caffeine is safe for most people in small to moderate doses, but it becomes dangerous when consumed in high amounts—especially in concentrated forms like powders or supplements. Children, teens, and pregnant women should be particularly cautious. And combining caffeine with alcohol can further increase health risks.
Knowing how much caffeine is in your drinks and snacks—and keeping your intake within safe limits—can help you enjoy its benefits while avoiding its dangers.
If you care about coffee, please read studies that drinking coffee this way can help prevent stroke, heart disease, and drink coffee after breakfast, not before, for better blood sugar control.
For more information about nutrition, please see recent studies about natural supplement that could relieve anxiety, and results showing this common food oil in the U.S. can change genes in the brain.
Copyright © 2025 Knowridge Science Report. All rights reserved.
