How Much Caffeine Is Too Much?
According to the FDA, 400 milligrams of caffeine a day, which is about four or five cups of coffee, is not generally associated with dangerous, negative effects for healthy adults.3
According to Palinski-Wade, children who consume large amounts of caffeine can experience hyperactivity, anxiety, racing heartbeat, insomnia, irritability, or in severe cases, caffeine overdose. A caffeine overdose can include vomiting, high blood pressure, racing heart, heart rhythm problems, disorientation, and hallucinations.
She also explained that caffeine has a half-life of 6 to 8 hours, which means in 6 to 8 hours, half of the caffeine consumed is still circulating in the body.
Side Effects of Too Much Caffeine
Consuming too much caffeine can cause the following:3
Food & Drug Administration. Spilling the beans: how much caffeine is too much?.
- Insomnia
- Jitters
- Anxiousness
- Rapid heart rate
- Upset stomach
- Nausea
- Headache
- A feeling of unhappiness (dysphoria)
Kids have an exaggerated response because they are smaller, so the effective dose—such as milligrams of caffeine in relation to body weight—is greater, said Temple.
Kids also don’t tend to consume caffeine on the same regular basis as adults do, so they are less likely to have developed a tolerance to its effects.
“This means that caffeine can have stronger effects at typical doses and that kids are less likely to experience withdrawal, so caffeine can have direct positive effects on kids as opposed to primarily acting by reversing withdrawal symptoms, which is common in adults who are regular consumers,” said Temple.
She noted that caffeine can be lethal at very high doses (about 10 grams), “but it would be nearly impossible to consume this much caffeine in its typical form, so lethal overdose occurs with the use of powdered caffeine.”
“However, we do not have data on higher levels nor do we have data on repeated consumption over time,” Temple said. “It is possible that it could have harmful physiological and psychological effects if multiple energy drinks are consumed in relatively close proximity to one another.”
Even if the drink is not particularly harmful, she noted that it does not have any known positive health benefits.
“[And] we know that it impacts sleep, so I caution parents to be aware of the caffeine content in the drinks that kids are consuming, limit any caffeine consumption in the afternoon and evening, and keep overall caffeine consumption to a minimum,” she said.
To find caffeine content in a variety of beverages, visit the U.S. Department of Agriculture‘s FoodData Central database.
How To Know if Your Coffee Habit Is Too Much Caffeine
How Caffeine Impacts Certain Medical Conditions
The American Academy of Family Physicians (AAFP) opposes the sale and marketing of energy drinks and related products to people under the age of 18 due to the inclusion of the following ingredients: caffeine, methylxanthines, B vitamins, guarana, yerba mate, bitter orange, ginger, ginkgo, St. John’s Wort, ginseng, and taurine.4
Stimulant ingredients in energy drinks and products may cause significant adverse health effects in vulnerable populations, particularly those with cardiac disease, asthma, and other conditions requiring the use of certain prescription medications. The stimulant ingredients can be especially dangerous when combined with other recreational substances.4
— AMERICAN ACADEMY OF FAMILY PHYSICIANS
For some people, high caffeine intake can spike blood sugar levels and blood pressure, making it potentially unsafe for those with underlying health issues, Palinski-Wade said.
When it comes to the heart, Mostafa El-Refai, MD, an interventional cardiologist at Norton Heart & Vascular Institute, said while several studies have looked at the effects of caffeine on the heart, data is conflicting.
For instance, while cardiologists used to advise people with atrial fibrillation and other arrhythmias to avoid caffeine, he said recent studies suggest that caffeine in moderation is safe and does not cause worsening of these conditions.
In general, he said moderate amounts of caffeine, equivalent to 1 to 3 cups of coffee, is considered safe.
“There are products out there with caffeine equivalent to more than 20 cups of coffee in one teaspoon. Caffeine in this extreme amount can cause a fast heart rate and an increase in blood pressure,” said El-Refai.
For those on heart medications, he said there are no known major interactions between heart medications and caffeine, but he recommended people should take note that “[some] over-the-counter and prescription cold and flu remedies can interact since some of the ingredients have stimulant effects.”
In addition to physical effects, caffeine can also have mental health ramifications.
According to a systematic review published in General Hospital Psychiatry, caffeine at doses roughly equivalent to 5 cups of coffee induced panic attacks in a large proportion of people with panic disorder (PD).5
In addition to increasing anxiety in people with PD, the review also found that caffeine at this level also increases anxiety in healthy adults, although the researchers noted that the exact relationship between caffeine-induced anxiety and panic attacks is still not known.5
The Best Way to Maintain Energy Levels
While caffeine may provide a tempting boost, Palinski-Wade said water is the best drink choice for staying well-hydrated and improving energy levels.
And if caffeine still tempts you, opting for a less intense option is a safer best.
“For adults, it is easy to enjoy moderate caffeine intake with a cup of brewed coffee or tea over an energy drink.”
