How much caffeine is too much?

Google “energy drinks” or “caffeine” these days, and you’ll get a mixed bag of reviews – depending on what you read, energy drinks and caffeine can boost metabolism, create a “brain boost” or be downright dangerous. New lawsuits related to energy drinks and caffeine prompt the question, “How much is too much?”

What’s Considered Safe?

Caffeine is a chemical stimulant that can be found naturally in coffee beans, tea leaves, cacao beans and other natural foods. It can also be synthetically added to drinks, foods, tablets and supplements. Most healthy adults can consume up to 400 milligrams of caffeine a day, according to the Food and Drug Administration. For reference, a 12-ounce can of a caffeinated soft drink typically contains 30 to 40 milligrams of caffeine, an 8-ounce cup of green or black tea 30 to 50 milligrams, one ounce of espresso has around 64 milligrams and an 8-ounce cup of coffee closer to 80 to 100 milligrams.

To the average coffee drinker, a limit of 400 milligrams of caffeine a day may sound reasonable since it’s the equivalent of two to four 8-ounce cups of coffee a day, depending on factors such as the type of bean and strength of the brew. But not everybody metabolizes caffeine in the same way – and some people may be more sensitive to its effects. Certain health conditions and some medications can also make people more sensitive to caffeine.

In addition, caffeine consumption has a way of sneaking up on us. “Two cups of coffee in the morning, a soda at lunch and an energy drink that afternoon may seem innocent enough, but this stacking up of the caffeine may cause side effects,” says Dr. Intekhab Syed with Sentara Clarksville Family Medicine.

“Having too much caffeine can lead to heart palpitations, anxiety, agitation, headaches and acid reflux,” he adds.

The Trouble with Energy Drinks

The energy drink market is growing rapidly, with more options available, often in innocent-looking, brightly colored packaging. Some energy drinks recently under scrutiny contain anywhere from 260 to 390 milligrams of caffeine per serving. For comparison, that’s more than six cans of caffeinated soda. Energy drinks usually contain not only high levels of caffeine but added sugar and other stimulants as well.

“There’s no legal limit for how much caffeine can be in an energy drink, so it’s on the consumer to track how much caffeine they’re consuming,” says Dr. Syed.

Dr. Syed recommends people with heart conditions avoid energy drinks because their high caffeine content can stress the heart. They may also have other ingredients like taurine, making the heart work harder when combined with caffeine. And people who take stimulant medication, such as Adderall, may also want to avoid energy drinks.

Pregnancy and Caffeine

Research suggests that moderate caffeine consumption (200 milligrams per day) does not cause miscarriage or preterm birth. But caffeine’s other side effects, such as the potential to interfere with sleep, contribute to nausea and cause light-headedness may be another reason to avoid it during pregnancy.

One recent study claims that children of women who consumed even low amounts of caffeine were shorter in stature than women who consumed no caffeine during pregnancy.

If you have questions about your caffeine consumption in pregnancy, discuss this with your care provider who can cover any questions you may have about caffeine consumption during pregnancy.  

“With the high percentage of caffeine in these energy drinks, it’s probably best to avoid drinking them during pregnancy,” says Dr. Syed.

Children, Teens and Caffeine

Caffeine is not recommended for children under 12, and those 12 to 18 should consume no more than 100 milligrams per day, according to the American Academy of Child and Adolescent Psychiatry. Many energy drinks contain enough caffeine to create a caffeine rush and a crash afterward along with other potentially serious side effects. This may be more pronounced in teens – who are often targeted by advertising by energy drinks. Despite these concerns, between thirty to fifty percent of adolescents report consuming energy drinks.

“A teen isn’t thinking about how much caffeine is in their drink,” says Dr. Syed. “They may quickly consume enough caffeine from an energy drink to have anxiousness, jitters, headaches and other side effects from too much caffeine. Not to mention how it will likely impact their sleep, which is so important to teens as their brains develop.”

Parents may want to talk to their teens about caffeine and energy drinks to educate them about the ingredients and potential side effects. Additional sources of caffeine in common energy drinks may also be “masked” by the labeling – but ingredients such as guarana, ginseng, and taurine are all sources of caffeine in the overall drink. Energy drinks in combination with alcohol or stimulant medications for children and teens treated for attention deficit hyperactivity disorder (ADHD) can make the side effects worse.

The Bottom Line

Consumers should pay attention to their daily caffeine intake when drinking highly caffeinated beverages. Pregnant and nursing women, as well as children and teens should avoid drinking energy drinks. People with heart concerns should also avoid drinking energy drinks and watch their overall intake of caffeine. Energy drinks should never be mixed with alcohol because energy drinks are stimulants while alcohol is a depressant. When mixing a stimulant and a depressant, it may mask the effects of intoxication, leading the person to drink more.

If you’re used to drinking caffeine-containing beverages every day and want to cut back, it’s best to do so gradually. Stopping abruptly can cause withdrawal symptoms such as headaches, anxiety, and nervousness. Caffeine withdrawal is not considered dangerous, but it can be unpleasant.