How Much Caffeine Is Too Much?

Last Update: July 5, 2024

Coffee. It fuels our mornings, invigorates our afternoons, and sometimes, gives us reason to brave the day.

With the ever-rising trends of latte art, slow pours, flat whites, and the need to stay constantly stimulated, it’s no surprise that Americans are hooked on the stuff. According to a Zagat survey of 1,500 coffee drinkers, people are willing to shell out (on average) $3.28 every day to sustain their habit. That’s around $100 per month!

Between energy drinks, sodas, and tea, coffee isn’t the only widely available source of caffeine available. It is, after all, the world’s most popular legal drug. If you’re doubling up, or relying on any of these to get you going, there’s a possibility you’re getting too much. But how much is too much? What are the adverse effects? Is there such a thing as overdosing on caffeine?

Here’s everything you need to know about caffeine, its effects, and whether or not you need to consider cutting back a bit.

The basics of caffeine

To put it plainly, caffeine is a psychoactive drug that’s legal and unregulated throughout the world. It works by blocking the action of chemicals in the brain that cause drowsiness—specifically, adenosine. It also helps stimulate different parts of the nervous system, leading to that “awake” feeling most people are after when they reach for a cup in the morning.

Caffeine is found in various nuts, seeds, and the leaves of different plants—the most notable is the Coffea plant. In some energy drinks, caffeine is extracted and turned into a pure, white powder before being added along with other naturally derived stimulants like taurine and ginseng.

Why is caffeine considered a drug?

Most of us think of coffee as something to help us wake up and put a little spring in our step. However, caffeine is classified as a drug. Here are some of the reasons why:

  • It directly impacts the chemical workings of the brain. By blocking certain receptors and stimulating others, it has a major influence on energy levels and mood.
  • Used in excess, it can be a detriment to health and well-being and, in very extreme cases, though rare, could lead to death.
  • It’s very addictive. In fact, caffeine addiction is a recognized medical condition in many areas of the medical community. While tolerance levels aren’t increased as with other drugs, mild physical dependence on coffee can occur. Those who stop drinking it often experience fatigue, stomach pain, headaches, difficulty concentrating, and other withdrawal symptoms.
  • There are numerous short- and long-term side effects associated with caffeine use, from diarrhea and stomach pain to headaches and nausea. Not all users experience them, but many do.

However, unlike many other drugs, caffeine does have some health benefits, and overall, is considered relatively safe. The American Medical Association Council on Scientific Affairs has issued a statement that moderate coffee or tea drinking is not likely to negatively influence your health if you have other healthy habits.

So, that leaves us with one question.

How much caffeine is too much?

We dive deeper into the different negative impacts caffeine can have on your health below. First, it’s worth taking a look at exactly how much is too much. Here are the primary things to understand.

Know your limits.

The average intake for Americans is around 400 mg—or roughly four 8-ounce cups of coffee. Beyond that level, you may begin to experience negative side effects.

Five cups is too much.

Drinking 500 to 600 mg a day (about five cups), especially in one sitting, could have a severe impact on your health.

Age matters.

Adolescents and teens should drink less coffee: About one cup per day is the recommended limit.

A little is probably OK during pregnancy.

Moderate coffee consumption—about one or two cups a day—is generally considered safe for pregnant women. But, as always, follow your doctor’s advice.

Listen to your body.

If you start to experience problems as a result of drinking caffeine (e.g. jitters, lack of concentration, nausea), stop drinking it for the day. Your body will tell you a lot about your own limits.

In general, if you’re a coffee drinker, four cups a day is a good rule of thumb, and spreading out your intake will help prevent many of the side effects of excessive coffee use. But most experts do recommend avoiding coffee after lunch—particularly for those who experience sleep problems (2 p.m. is a good general cutoff time to stick to).

What happens when you drink too much caffeine?

So what if you do go over the daily recommended limit? More than four cups a day could be putting you in the danger zone. A study by the Mayo Clinic found that young men who drank more than 28 cups of coffee per week had a 56 percent increased risk of death from all causes.

But for the average java sipper, there are some physical side effects—ranging in severity—to be aware of, too. Depending on your body and how much coffee you drink, you may experience none of these symptoms, some of them, or all of them. The important thing to understand is that moderate coffee use is safe and could even be good for you. Just don’t overdo it.

  • Heartburn: Caffeine can cause the esophagus to relax, triggering gastroesophageal reflux. This leads to serious heartburn, and is even worse in those with existing reflux disorders.
  • Jitters: The stimulant effects of caffeine can trigger tremors and jitters in the body, because it increases adrenaline.
  • Rapid heartbeat: Within 15 minutes of drinking caffeine, the heart rate will rise. And generally, the more you drink, the more the heart rate climbs.
  • Anxiety: Due to the increased hormone production, rapid heart rate, and increased mental acuity caused by caffeine, those who drink too much of it can feel anxious. For those with anxiety disorders, the sensation is often worse.
  • Heart “flutters”: Not only can the heart rate speed up, but it can also flutter wildly due to excessive caffeine consumption.
  • Muscle spasms: This is a sign that you’re getting entirely too much caffeine. An excess can lead to involuntary muscle cramps, twitches, and spasms.
  • Difficult speech: It’s true that caffeine will make it easier to concentrate, but the stimulant effects mean that your speech and thought can speed up as well. This can lead to distorted speech, stuttering, and other similar problems.
  • Headache: Too much caffeine can also bring on severe headaches, often due to the brain receptors becoming overloaded.
  • Insomnia: We drink caffeine to stay awake, but sometimes it becomes almost impossible to get to sleep if you’ve had too much joe. (Hence the aforementioned 2 p.m. cutoff recommended by most experts.)
  • High blood pressure: When you take in caffeine, your body releases more adrenaline. This in turn can cause the blood pressure to rise dramatically.
  • Ulcers: The stomach lining can become damaged due to caffeine as well, and excessive amounts can lead to stomach ulcers.
  • Diuresis: You’ll urinate more when you drink caffeine because it increases the blood flow through the kidneys. Overdo it, and the excess blood flow could lead to kidney damage.
  • Dehydration: Drinking coffee constantly can mean persistent urination and diarrhea. This in turn can cause dehydration (sipping water alongside your coffee can help).

Caffeine overdose

In general, caffeine’s effects last roughly four to six hours. In extreme cases, drinking too much within a short period of time can lead to an overdose. This can bring on serious health risks including:

Heart attack

High levels of caffeine can cause your heart rate and blood pressure to increase. When this happens, the cardiovascular system may experience a shutdown. Those with weaker hearts are at a higher risk for this.


Caffeine intoxication leads to severe confusion and disorientation—and can even be followed by a caffeine-induced coma, seizures, and other similar problems.


It surprises many to learn that caffeine can be fatal. Death related to drinking coffee is extremely rare. But taking caffeine pills (or even downing energy drinks) with impunity can lead to death.

Obviously, you have to ingest a lot of caffeine to reach this point. As such, your body will usually begin to exhibit warning signs before an overdose occurs. If you experience any of the following issues after drinking a lot of coffee, you should stop immediately and let your body process the caffeine:

  • Sweating
  • Dizziness
  • Vomiting
  • Anxiety
  • Nausea
  • Dramatically increased heart rate
  • Difficulty focusing

Long-term impacts of too much caffeine

Everything we’ve gone over up to this point is primarily focused on the short-term consequences of drinking too much caffeine. It’s also worth noting that there are long-term impacts of excessive consumption as well. Due to caffeine’s four to six hour half-life—the time it takes to break down in the body—most symptoms like dizziness or anxiety fade within that timeframe. But some damage can linger including:

  • Dehydration: This was mentioned above, but deserves another look. Long-term use of caffeine can bring about chronic dehydration. Counteract this by drinking a lot of water throughout the day.
  • Kidney damage: Caffeine increases the blood flow to the kidneys, requiring them to work harder. This can result in kidney damage over time.
  • Insomnia: As caffeine intake increases, it can dramatically alter your sleep patterns—which could lead to difficulty sleeping even when you haven’t consumed any that day.
  • Addiction: This is probably the most common long-term effect of caffeine use. When you drink too much and your body starts to rely on it, you can develop headaches and irritability when you don’t get your fix.

Final thoughts

There’s plenty of evidence that moderate caffeine intake (about two to four cups per day), in particular coffee, does have health benefits—including a reduced risk of heart disease, stroke, and heart failure. However, it’s important you don’t go overboard. To be sure you’re not getting too much caffeine, stick to recommended limits, stop drinking it if you begin feeling jittery or experience negative side effects, and avoid sugary energy drinks entirely.

The good news is you don’t have to quit the stuff cold turkey. In fact, a little bit can do you good, but coffee consumption is something that you should monitor and moderate. Doing so will help ensure you stay healthy while getting that morning energy burst.

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