What is caffeine?

Caffeine is a chemical found in coffee, tea, yerba mate, and many other foods and beverages. It's hard to determine precisely how much caffeine a specific serving of coffee, but a safe dose for most adults is 400 milligrams.
Caffeine is a chemical found in coffee, tea, yerba mate, and many other foods and beverages. It's hard to determine precisely how much caffeine a specific serving of coffee, but a safe dose for most adults is 400 milligrams.

Coffee is the beverage of choice to start the morning for many people. While caffeine is usually considered safe for most people, there is a recommended limit to how much you should take in a single day. Over that amount can lead to severe side effects, such as nausea, headaches, jitteriness, and restlessness. Here’s everything you need to know.

Caffeine is a chemical found in coffee, tea, yerba mate, and many other foods and beverages. It’s considered a drug because of its stimulating effects — however, it’s also deemed safe for most people in low doses.

When you drink coffee or any other source of caffeine, the chemical is absorbed in a relatively short time through your liver. After only about five minutes, you may start feeling an increase in your ability to focus, mental clarity, and heart rate. These effects can last for up to 12 hours depending on each person. 

Other common effects of caffeine are:

  • Increased breathing rate
  • Feeling more alert
  • Decrease in tiredness
  • Improved physical and creative work

Yet, there are also some side effects. While most severe signs come from taking too much caffeine, some people are prone to headaches and anxiety from as limited exposure as a single serving. Other common side effects caused by average amounts of caffeine can include stomachaches and jitteriness, and frequent urination

As we all know, many people choose to start their mornings with a cup of coffee, but many aren’t aware that quitting this habit is harder than it seems. Coffee withdrawal is no joke, as stopping your caffeine intake can lead to:

The easy way to avoid this is to limit the caffeine you take regularly. You’ll not only avoid withdrawal symptoms but also prevent caffeine tolerance, which means needing to take more and more caffeine over time to feel the desired effects.

How much caffeine is in coffee?

\It’s hard to determine precisely how much caffeine a specific serving of coffee has, as it varies depending on the size of a serving, chemical components, and brewing method. However, you can follow a few general guidelines to get an idea of how high your caffeine intake is.

  • An 8-ounce serving of brewed coffee has between 80 and 115 milligrams of caffeine
  • Espresso and cappuccino have about 80 milligrams per 2-ounce serving
  • Instant coffee has between 48 to 88 milligrams per 5-ounce serving

Logically, coffee is the beverage with the highest concentration of overall caffeine. Yet, not many people know this chemical is also found in other everyday foods. For example, tea, yerba mate, and cola beverages all contain some caffeine. 

  • An 8-ounce cup of black tea provides approximately 47 milligrams of caffeine
  • Both diet and regular cola soda have about 40 milligrams per 12-ounce serving.
  • Chocolate has 24 milligrams per ounce
  • Energy drinks usually contain a shocking 170 milligrams per 16-ounce serving

While these approximations are generally applicable, it’s recommended that you check the label of each specific product if you’re trying to monitor your intake. 

How much caffeine is too much?

Unfortunately, there’s no quick way of telling how much caffeine each person can tolerate. The amount depends on many factors, such as size, tolerance, health conditions, and weight. Still, experts have some recommendations regarding the limit of daily caffeine.

Research indicates that the safe daily caffeine dose for most adults is 400 milligrams — the equivalent of about four cups of brewed coffee. Luckily, the average intake for adults in the U.S. is much lower, about one and a half cups instead.

Yet, some people have to take special precautions with caffeine. Pregnant women should limit their intake to 200 milligrams, while teens should keep it to about 100. 

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What are the side effects of taking too much caffeine?

Going over the recommended daily caffeine intake can lead to severe long- and short-term side effects. However, this chemical affects everyone differently, so  some people may be more resistant to it due to weight, genes, and other factors.

In the short term, going over the recommended dose of caffeine can lead to dehydration, a rise in body temperature, and restlessness. Headaches and dizziness are also common, along with anxiety and irritability. On top of that, despite the stimulant effects of caffeine, people report an overwhelming feeling of tiredness after coming down from too much coffee.

Caffeine can lead to diarrhea, tremors, panic attacks, and even seizures in more severe cases. These signs usually mean that you had a caffeine overdose, so don’t hesitate to go to the hospital if you feel any of them. Yet, it’s unlikely that you’ll experience them, as these levels aren’t usually reached through caffeinated drinks.

Long-term caffeine use also leads to side effects — especially when someone is taking more than 400 milligrams a day. This repeated, heavy use may lead to anxiety, insomnia, irritability, and low blood pressure.

Other common side effects of heavy, long-term caffeine use include:

If you feel any of the effects mentioned above, you may want to check whether you consume more than the recommended daily caffeine dose. If that isn’t the case, make sure to get an appointment with your doctor to see if you’re overly sensitive to coffee.

How can I cut back on caffeine?

If you want to cut back on caffeine, there are a few guidelines to ensure as few withdrawal symptoms as possible. For example, you can try replacing caffeinated drinks with decaffeinated variants or plain water. Start slowly, as stopping all of your caffeine intake at once can lead to undesirable effects.

You’ll sometimes feel tired, but that should go away within a couple of days as you further cut back on caffeine. If you have any doubts, don’t hesitate to check with a doctor, as they’ll be able to give precise advice relevant to your particular situation.

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Medically Reviewed on 7/19/2022
References
SOURCES:

Alberta Health Services: "Caffeine."

Alcohol and Drug Foundation: "Caffeine."

Better Health: "Caffeine."

Food & Function: "Variations in caffeine and chlorogenic acid contents of coffees: what are we drinking?"

Harvard School of Public Health: "Caffeine."

Neumors KidsHealth: "Caffeine."

Princeton University Health Services: "Caffeine."