8 Side Effects of Consuming Too Much Caffeine

Some forms of beverages contain caffeine, a drug that can boost your mood, mental efficiency, and metabolism.

Studies have also shown that intake in low-to-moderate quantities is healthy for most people.

Many people consume much more caffeine than others without having negative effects.

People who are not used to caffeine may experience symptoms after consuming what we typically consider a moderate dose.

Here are eight side effects of consuming too much caffeine.

1. Insomnia

One of its most valuable attributes is the power of caffeine, which can help people stay awake.

It’s hard to get enough restorative sleep while consuming too much caffeine.

Studies have found that consuming too much caffeine seems to increase the time required to fall asleep (1, 2).

It may also reduce total sleep time for elderly people. An energy shot, for example, contains up to 350 mg of caffeine, while some energy drinks provide as much as 500 mg per can (3).

It depends on your genes and other factors as to how much caffeine you can drink without disrupting your sleep.

Caffeine ingested in the evening can interfere with sleep because it may take several hours to wear off its effects.

A study has shown that caffeine stays in your body for an average of five hours (4).

The time could vary from one hour to nine hours.

One study examined the effects of caffeine on influencing sleep timing.

Researchers gave 400 mg of caffeine to 12 healthy adults either six hours before bedtime, three hours before bedtime, or just before bedtime.

All three participants struggled to fall asleep, and the time they spent awake at night increased (5).

These results suggest it is important to pay attention to the timing of consuming caffeine to optimize your sleep.

2. Muscle Breakdown

Rhabdomyolysis is a potentially life-threatening syndrome that reaches the bloodstream by breaking through muscle fibers, leading to kidney failure and other complications such as toxicity.

Some cases of rhabdomyolysis have been reported because of consuming too much caffeine, although this is rare (6, 7, 8, 9).

In one instance, after drinking 32 ounces of coffee containing around 565 mg of caffeine, a woman experienced nausea, diarrhea, and dark urine.

After being provided with drugs and fluids, she recovered (9).

This is a large dose of caffeine that can be absorbed in a short time for someone who is not used to it or who is sensitive to its effects, and they will usually experience symptoms.

To reduce the risk of rhabdomyolysis, it is best to limit your consumption to 250 mg of caffeine per day.

3. High Blood Pressure

In most cases, caffeine does not appear to increase the risk of heart disease or stroke.

Because of its stimulating effect on the nervous system, however, it has been shown to increase blood pressure in several studies (10, 11, 12, 13).

High blood pressure is a risk factor for heart attack and stroke because it can damage the arteries, reducing blood flow to your heart and brain.

The effect of caffeine on blood pressure is temporary.

For healthy people and those with elevated blood pressure, consuming too much caffeine can increase blood pressure during exercise (14, 15).

If you have high blood pressure, it is important to pay attention to the dosage and timing of caffeine.

4. Frequent Urination

Greater urination is due to the stimulating effects of the compound on the bladder, which is a common side effect of consuming caffeine.

You may have noticed that when you drink more coffee or tea than usual, you need to urinate more frequently.

Some studies have concentrated on older people and those with overactive bladders or incontinence to investigate the effects of the compound on urinary frequency (16, 17, 18).

However, one study found that 12 young to middle-aged adults with overactive bladders who ingested 2 mg of caffeine per pound (4.5 mg per kg) of body weight daily reported significant increases in urine frequency and urgency (17).

This equates to around 300 mg of caffeine per day for someone weighing 150 pounds (68 kg). 

In people with healthy bladders, increased intake may raise the probability of developing incontinence.

One comprehensive study investigated the effects of high caffeine consumption on incontinence in over 65,000 women.

Those who consumed over 450 mg of caffeine a day had a higher risk of incontinence compared to those who consumed less than 150 mg a day (18).

If you drink a lot of caffeinated beverages and notice that your urination is becoming more frequent or urgent, reducing your caffeine intake may be a good way to see if your symptoms improve.

5. Anxiety

One of the psychoactive effects of caffeine is that it increases alertness. This works by blocking adenosine’s influence, a brain chemical that makes you feel tired.

Similarly, caffeine enhances neural activity in the brain, which the pituitary gland perceives as an emergency and stimulates the adrenal glands to release the adrenaline hormone, which increases energy (19).

Such symptoms, however, may become more intense at higher doses of caffeine, resulting in anxiety and nervousness.

Caffeine-related anxiety disorder is also one of the caffeine-related syndromes.

A daily intake of 1,000 mg or more per day in most people has been documented to cause nervousness, jitteriness, and similar symptoms, whereas even low intakes may lead to similar effects in people sensitive to caffeine (20, 21).

When ingested in a single sitting, small amounts induce fast breathing and an increase in stress levels (22, 23).

In one study of 25 healthy males, those who consumed around 300 mg of caffeine had more than twice the stress as those who took a placebo.

Interestingly, stress levels were comparable across regular and less frequent caffeine consumers, implying that the chemical may have the same effect on stress levels regardless of whether you drink it on a regular or irregular basis (23).

It may be an excellent idea to look at your consumption of caffeine and cut it back if you find that you often feel nervous.

6. Digestive Issues

A morning cup of coffee makes many people move their bowels. They attributed the laxative effect of coffee to gastrin release.

The stomach produces this hormone to speed up activity in the colon. However, decaffeinated coffee has been shown to produce a similar effect (24, 25, 26).

Similarly, caffeine appears to increase bowel motions by enhancing peristalsis, or the contractions that move food through your digestive tract (26).

It is not surprising that excessive caffeine consumption can result in loose stools or even diarrhea in some people.

While they thought coffee could cause stomach ulcers for many years, there was no correlation between ulcers and coffee in one study of over 8,000 people (27).

According to some studies, caffeinated beverages may exacerbate gastroesophageal reflux disease (GERD) in some people (28, 29, 30).

This appears to be true for coffee. In one small study, five healthy adults who drank caffeinated drinks noticed a relaxation of the muscle that prevents stomach contents from going up into the esophagus, which is a common symptom of GERD (30).

While coffee has major effects on digestive function, if you have any complications, cut back on how much you drink or switch to tea.

7. Fatigue

We understand that coffee, tea, and other caffeinated beverages raise energy levels. It may also have the opposite effect, however, by causing exhaustion after caffeine withdrawal from the body.

A study found that while caffeinated energy drinks increased alertness and improved mood for several hours, the following day, participants were often more tired than usual (31).

You can stop the withdrawal effect if you continue to drink plenty of caffeine throughout the day, which can also affect your sleeping capacity.

Use it in moderate rather than high doses to maximize the benefits of caffeine on energy and prevent caffeine withdrawal symptoms.

8. Addiction

The caffeine in coffee and tea is a stimulant drug that can become habit-forming. According to a detailed review (32), while caffeine activates some brain chemicals similar to cocaine and amphetamines, it does not induce classic dependence in the manner in which these substances do.

It may, however, lead to psychological or physical dependency at high doses.

In one study, 16 people who consumed high, moderate, or no caffeine, took part in a word test after being caffeine-free for the night (33).

Only caffeine addicts displayed a bias for caffeine-related words and had significant coffee cravings.

The frequency with which they use caffeine appears to play a role in dependency.

Another study of 213 caffeine consumers found that after 16 hours without drinking coffee, regular caffeine consumers had higher rates of headaches, exhaustion, and other signs of withdrawal than non-regular users (34).

While the compound does not seem to cause true dependence if you drink a lot of coffee daily, you may become dependent on its effects.


Moderate consumption of caffeine provides many people with remarkable health benefits.

Consuming too much caffeine can cause side effects.

This can interfere with everyday life and may even cause serious health problems.

Although responses differ from person to person, results suggest a high intake of caffeine is not better.

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