Side Effects of Caffeine (How Much Caffeine Is Too Much?)

Donald Christman
Published by Donald Christman | Medical Student and Professional Journalist
Last updated: November 23, 2023
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Case studies show that caffeine overdose can lead to major outcomes and, in rare instances, even death.

This shows that even though helpful, caffeine is still a drug, and too much caffeine can cause various side effects.

So, after sifting through relevant scientific papers and following that with an in-depth interview with my physician, I decided to gather all the potential dangers of caffeine usage in this article.

Here’s what you need to know.

Quick Summary

  • Caffeine side effects vary from mild to dangerous and can be both short-term and long-term.
  • Side effects of caffeine usually occur when the recommended daily doses are exceeded, but depending on individual caffeine sensitivity, they may occur at lower doses.
  • When reducing or stopping your daily caffeine intake altogether, you should do it gradually to avoid unpleasant withdrawal effects.

Caffeine Side Effects

A man holding a cup of coffee

Even though studies have shown that consuming caffeine is safe in low-to-moderate amounts for most people, you must still be mindful of its usage since it’s a potent stimulant [1].

Most often, side effects occur when consuming too much caffeine (we’ll discuss the adequate dosage later).

Depending on the effect’s duration and type, we can separate them into short-term and long-term.

Let’s see those effects closer.

Short-term Side Effects

Short-term effects are more common for occasional caffeine consumers.

They will most likely happen to individuals who aren’t used to caffeine, as their bodies will react differently to what’s typically considered a moderate dose.

However, regular consumers may also experience these side effects when they take more than usual.

Most of the time, the dose determines whether the impact will be mild (like a flushed face) or dangerous (fast and irregular heartbeat) [2].

Here’s the list of the potential short-term side effects: 

  • Headaches
  • Anxiety
  • Flushed face
  • Insomnia
  • Frequent urination
  • High blood pressure
  • Irritability
  • Muscle tremors
  • Upset stomach
  • Fast or irregular heartbeat

As we mentioned earlier, these effects have a short lifespan and, unless you’ve taken a very high dose, won’t lead to serious health complications (according to the FDA, a dose of 1200 mg of caffeine in a too short time can be fatal) [3].

Long-term Side Effects

A man suffering from a headache because of too much coffee

Caffeine consumption or overconsumption might also cause long-term side effects like chronic insomnia, stomach problems, or constant anxiety [4].

However, most commonly, regular caffeine intake will cause you to develop caffeine dependence.

Caffeine dependence manifests as both physical and psychological addiction.

You can become mildly addicted to caffeine by regularly drinking 2 - 4 cups of coffee a day (350 mg).

This often causes people to experience withdrawal symptoms even after several hours without an expected dose of caffeine (for people who regularly consume caffeine in large amounts) [5].

Caffeine withdrawal symptoms include:

  • Headache
  • Nausea
  • Poor mood
  • Mental fog
  • Lightheadedness

So, how can you stay within the safe range?

How Much Is Too Much?

A man drinking coffee from a cup

If your overall health is good, around 200 mg of caffeine (1 - 2 cups of coffee) can make you more alert, put you in a better mood, and improve your cognition.

And according to the aforementioned FDA document, a dose of up to 400 mg of caffeine daily appears safe for most healthy adults.

That’s roughly the amount of caffeine in 10 cans of cola, four cups of brewed coffee, or two energy drinks.

However, the caffeine content in these beverages varies widely, especially in energy drinks [6].

The optimal dose still depends on your caffeine sensitivity and how much caffeine you typically consume daily. 

Keep in mind that depending on some genetic idiosyncrasies, caffeine intake might need to be severely limited or entirely avoided [7].

Categories at Risk

A child holding a cup of coffee

Even though there are no official FDA recommendations on how much caffeine children should consume, the general consensus is that children should avoid caffeine intake altogether.

However, Canada recommends limiting caffeine to no more than 2.5 mg per 2.2 lbs of body weight for children under 18 [8].

Women who are pregnant, trying to become pregnant, or breastfeeding should limit their caffeine use to less than 200 mg a day (one and a half 8-ounce cups of coffee) as caffeine affects important pregnancy parameters like blood pressure and heart rate [9].

Situations in Which You Should Be Cautious

You should be careful if you take certain medications since caffeine can alter their effects and decrease or increase how much medicine is absorbed [10].

The most common interaction happens with the following medications:

  • Migraine medications
  • Antibiotics
  • Cancer medications
  • Thyroid medications
  • Anticoagulants
  • Blood pressure drugs
  • Asthma medications
  • Antidepressants
  • Sedatives
  • Estrogen
  • NSAIDs

Caffeine may also interfere with some dietary supplements, so it’s a good idea to speak with your pharmacist or doctor if you take any medications or supplements.

How to Curb Your Intake?

A woman holding coffee in an office

To curb your caffeine intake, you should be persistent, as caffeine is addictive and halting consumption can be quite challenging.

To break, or curb your caffeine habit, try these approaches:

  • Keep track of how much caffeine you ingest - Read the labels of foods and beverages you consume, as a wide array of products contain it (i.e., over-the-counter pain relievers).
  • Taper off the caffeine - Choose a smaller cup of coffee or drink one less caffeinated drink a day. Unlike quitting cold turkey, the body will get used to the lower levels of caffeine and alleviate potential withdrawal effects [11].
  • Go decaf - Try ordering decaffeinated coffee, switching your energy drink for a soft drink, or a cup of tea for herbal. Also, drink more water instead of caffeinated beverages to help you keep your energy levels and mood high [12].
  • Switch to a healthy lifestyle - Eat more whole foods filled with nutrients and start being more active to increase mental concentration, rev up energy levels, and improve sleep quality [13].

“Don’t cut out caffeine completely all of a sudden because then you may experience some bad withdrawal syndromes.

- Dr. Nicole Clark, Neurologist

You should try out these tips and find what works best for you.


Does Caffeine Cause Depression?

No, caffeine doesn’t cause depression. However, for people who are sensitive or have too much caffeine, there may be an indirect link, as caffeine-induced serotonin levels can fall, leading to crashes or interfering with sleep quality.

Is It Ok to Drink Caffeine Every Day?

Yes, it’s ok to drink caffeine every day as long as the dose doesn’t exceed the recommended 400 mg. It’s the amount not generally associated with dangerous and harmful effects on the body.


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