Caffeine is a stimulant found in various foods, drinks, and other products such as coffee It’s commonly used to keep you awake and alert. Caffeine is technically a drug. Coffee is one of the most popular beverages in the world and many people globally start their day with a cuppa. While there are many benefits to consuming coffee, there can also be side effects if too much is consumed.
For our article on the benefits of coffee, please click here.
According to the Mayo Clinic, the recommended daily intake of caffeine is up to 400 milligrams for healthy adults. Caffeine overdose may occur if you ingest more than this amount.
Adolescents should limit themselves to no more than 100 mg per day while pregnant women are advised to limit their daily intake to less than 200 mg of caffeine per day. It is important to note that what constitutes a safe amount of caffeine differs for everyone based on their respective ages, weight, and overall health.
The average half-life of caffeine in the blood ranges from 1.5 to 9.5 hours. This means it can take anywhere from 1.5 to 9.5 hours for the level of caffeine in your blood to drop to half of its original amount. This wide range in average half-life makes it difficult to know the exact amount of caffeine that can lead to overdose.

What are the common side effects of too much caffeine?
- Anxiety
While coffee is known to help with alertness, the flip side of this is that it can also result in anxiousness.
Caffeine-induced anxiety disorder is one of four caffeine-related syndromes listed in the Diagnostic and Statistical Manual of Mental Disorders (DSM), which is published by the American Psychiatric Association.
Extremely high daily intakes of 1,000 mg or more per day have been reported to cause nervousness, jitteriness and similar symptoms in most people, whereas even a moderate intake may lead to similar effects in caffeine-sensitive individuals.
As such, If you notice that you often feel nervous or jittery, it might be a good idea to look at your caffeine intake and cut it back.
2. Indigestion and other digestion issues
While some find that a morning cup of coffee helps get their bowels moving. Others have experienced overstimulation in the digestive system. Large doses of caffeine may lead to loose stools or even diarrhoea in some people.
Some studies also suggest that caffeinated beverages may worsen gastroesophageal reflux disease (GERD) in some people. This seems to be especially true of coffee. In a small study where five healthy adults drank caffeinated water, they experienced a relaxation of the muscle that keeps stomach contents from moving up into the throat — the hallmark of GERD.
3, Insomnia
Given that coffee is known to help with alertness, it is par for the course that too much of it can trigger an inability to sleep.
Studies have found that higher caffeine intake appears to increase the amount of time it takes to fall asleep. It may also decrease total sleeping time, especially in the elderly.
It is important to note that the amount of caffeine you can consume without affecting your sleep will depend on your individual genetics and other factors. As such, pay attention to your own body’s reactions and moderate accordingly.
Studies have also indicated that caffeine consumed later in the day may interfere with sleep because its effects can take several hours to wear off. Research has shown that while caffeine remains in your system for an average of five hours, the time period may range from one and a half hours to nine hours, depending on the individual.

4. Muscle Degeneration
Consuming excessive caffeine within a short period of time, especially for someone who isn’t used to it or is highly sensitive to its effects can result in a serious condition called Rhabdomyolysis in which damaged muscle fibres enter the bloodstream, leading to kidney failure and other problems.
While this is rare, it can happen and it is important for us to be aware.
In order to reduce the risk of rhabdomyolysis, it’s best to limit your intake to about 250 mg of caffeine per day, unless you are used to consuming more.
5 Addiction
Some studies have indicated that drinking coffee may lead to psychological or physical dependency, especially at high dosages.
If you regularly drink a lot of coffee or other caffeinated beverages, there’s a very good chance you may become dependent on its effects. Regular drinkers have reported greater increases in headaches, fatigue and other withdrawal symptoms if they don’t get their cuppa.
6. High blood pressure
The stimulant effect caffeine has on the nervous system can lead to an increase in blood pressure. Elevated blood pressure is a risk factor for heart attack and stroke because it may damage arteries over time, restricting the flow of blood to your heart and brain. Therefore, paying attention to the dosage and timing of caffeine is important, especially if you already have high blood pressure.
7. Heart palpitations
The stimulatory effects of high caffeine intake may cause your heart to beat faster.
It may also lead to altered heartbeat rhythm, called atrial fibrillation, which has been reported in young people who consumed energy drinks containing extremely high doses of caffeine. However, this effect doesn’t seem to occur in everyone. Indeed, even some people with heart problems may be able to tolerate large amounts of caffeine without any adverse effects.
While studies have been inconclusive on this if you notice any changes in your heart rate or rhythm after drinking caffeinated beverages, consider decreasing your intake.

8. Fatigue
While caffeine is known to boost energy levels, it can also have the opposite effect by leading to rebound fatigue after the caffeine leaves your system. Of course, if you continue to drink lots of caffeine throughout the day, you can avoid the rebound effect. On the other hand, this may affect your ability to sleep.
To optimise caffeine’s benefits on energy and avoid rebound fatigue, consume it in moderate rather than high doses.
9. Increased need to go to the toilet
Increased urination is a common side effect of high caffeine intake due to the compound’s stimulatory effects on the bladder.
If you drink a lot of caffeinated beverages and feel that your urination is more frequent or urgent than it should be, it may be a good idea to cut back on your intake to see if your symptoms improve.
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