Here's Exactly How Much Caffeine Is Too Much Caffeine
If you're like most Americans, you're reaching for your coffee first thing in the morning. A 2018 study from the National Coffee Association found that 64 percent of Americans drink a cup of coffee every day, up from 62 percent in 2017, and the highest percentage since 2012.
But it's not just the coffee we're after—it's the caffeine. And whether your drink of choice is a latte, tea, or soda, you'll definitely get a fix. However, it can also have some pretty unpleasant side effects. Here's everything you need to know about caffeine and how to consume it safely.
What is caffeine?
"Caffeine is a drug (yep!) and central nervous stimulant," says Monica Auslander Moreno, MS, RD, LD/N, registered dietitian and nutrition consultant for RSP Nutrition. "It has been known to aid with attention and reactive time, as well as provide more energy, strength, and endurance for physical activities. It is a gastric stimulant, and also a vasoconstrictor (it raises blood pressure)."
How much caffeine is safe to consume daily?
The 2015-2020 Dietary Guidelines suggest up to 400 milligrams per day is safe for most healthy adults. (That's 3-5 cups of coffee per day.) In pregnancy, current guidelines recommend less than 200 milligrams per day.
However, each person's body reacts differently to it.
"Individual metabolism and tolerance should dictate this, and not guidelines," says Auslander Moreno. "We do not recommend caffeine for children, other than small amounts occurring in chocolate."
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What are the symptoms of too much caffeine?
There is definitely such a thing as too much caffeine, and your body will let you know.
"Consuming more than 400 milligrams of caffeine can result in a jumpy and slightly alarmed feeling," says Lauri Wright, PhD, RDN, LD, spokesperson for the Academy of Nutrition and Dietetics.
Wright says larger amounts of caffeine may cause:
The caffeine content in popular drinks
Here's how much caffeine is in your favorite drinks.
- Coffee: "A cup (8 oz) of brewed coffee can have various caffeine amounts—from 70-140 milligrams per cup, depending on brew and bean," says Auslander Moreno.
- Espresso: 64 mg per 1 oz.
- Decaf coffee: 12-15 mg per cup
- Black tea: ~50 mg per cup (depends on variety + steep time)
- Green tea: 35-50 mg per cup (depends on variety + steep time)
- Soda: Coke: ~34 mg per 12 oz can
- Diet Coke: ~ 46 mg per 12 oz can
- Pepsi: ~39 mg per 12 oz can
- Diet Pepsi: ~35 mg per 12 oz can
- Coke Zero: ~36 mg per 12 oz can
- Barq's Root Beer: ~ 38 mg per 12 oz can
- Mountain Dew: ~54 mg per 12 oz can
Can you have caffeine withdrawal?
Yes, you can, and it can be both physical and mental.
"You can have a physical (and psychological) dependence on caffeine," says Auslander Moreno.
The most commonly reported caffeine withdrawal issues are:
- decreased concentration
How long until caffeine is completely out of your system?
"The half-life of caffeine (the amount of time until HALF a sample is metabolized) is about 5-6 hours, but tolerance and DNA can move this number significantly," says Auslander Moreno. "That's why some people find it useful to have a rather early 'cutoff time' for caffeine intake since it may be disrupting sleep far later at nighttime."
If you do overdo it, unfortunately, you can't flush it out of your system.
"Drinking water may make some symptoms feel a bit better, but the drug has to be metabolized in time," says Auslander Moreno. "The half-life is about 5-6 hours, but individual metabolisms vary widely."
How much caffeine can kill you?
It's true: Caffeine can kill you. According to the FDA, it has contributed to the deaths of at least 2 Americans.
The FDA estimates toxic effects, like seizures, can be observed with rapid consumption of around 1,200 milligrams of caffeine, or 0.15 tablespoons of pure caffeine.