Coffee and tea are incredibly healthy beverages. Most types contain caffeine, a substance that may boost your mood, metabolism and mental and physical performance. However, high doses of caffeine may have unpleasant and even dangerous side effects. What’s more, individuals who aren’t used to caffeine may experience symptoms after consuming what is typically considered a moderate dose. Here are 9 side effects of too much caffeine.
Caffeine is known to increase alertness. It works by blocking the effects of adenosine, a brain chemical that makes you feel tired. At the same time, it triggers the release of adrenaline, the “fight-or-flight” hormone associated with increased energy .
However, at higher doses, these effects may become more pronounced, leading to anxiety and nervousness. In fact, 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 .Additionally, modest doses have been shown to cause rapid breathing and increase stress levels when consumed in one sitting. One study in 25 healthy men found that those who ingested approximately 300 mg of caffeine experienced more than double the stress of those who took a placebo.
Interestingly, stress levels were similar between regular and less frequent caffeine consumers, suggesting the compound may have the same effect on stress levels regardless of whether you drink it habitually. Nevertheless, these results are preliminary.
Caffeine’s ability to help people stay awake is one of its most prized qualities. On the other hand, too much caffeine can make it difficult to get enough restorative 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. By contrast, low or moderate amounts of caffeine don’t seem to affect sleep very much in people considered “good sleepers,” or even those with self-reported insomnia. You may not realize that too much caffeine is interfering with your sleep if you underestimate the amount of caffeine you’re taking in.
Although coffee and tea are the most concentrated sources of caffeine, it is also found in soda, cocoa, energy drinks and several types of medication. For example, an energy shot may contain up to 350 mg of caffeine, while some energy drinks provide as much as a whopping 500 mg per can.
These results suggest that it’s important to pay attention to both the amount and timing of caffeine to optimize your sleep.
3. Digestive Issues
Many people find that a morning cup of coffee helps get their bowels moving. Coffee’s laxative effect has been attributed to the release of gastrin, a hormone the stomach produces that speeds up activity in the colon. What’s more, decaffeinated coffee has been shown to produce a similar response.
However, caffeine itself also seems to stimulate bowel movements by increasing peristalsis, the contractions that move food through your digestive tract. Given this effect, it’s not surprising that large doses of caffeine may lead to loose stools or even diarrhea in some people. Although for many years coffee was believed to cause stomach ulcers, a large study of more than 8,000 people didn’t find any link between the two.
On the other hand, some studies 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, when 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.
Since coffee can have major effects on digestive function, you may want to cut back on the amount you drink or switch to tea if you experience any issues.
4. Muscle Breakdown
Rhabdomyolysis is a very serious condition in which damaged muscle fibers enter the bloodstream, leading to kidney failure and other problems. Common causes of rhabdomyolysis include trauma, infection, drug abuse, muscle strain and bites from poisonous snakes or insects. In addition, there have been several reports of rhabdomyolysis related to excessive caffeine intake, although this is relatively rare.
In one case, a woman developed nausea, vomiting and dark urine after drinking 32 ounces (1 liter) of coffee containing roughly 565 mg of caffeine. Fortunately, she recovered after being treated with medication and fluids.
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’re used to consuming more.
Despite all of caffeine’s health benefits, there’s no denying that it may become habit-forming. A detailed review suggests that although caffeine triggers certain brain chemicals similarly to the way cocaine and amphetamines do, it does not cause classic addiction the way these drugs do. However, it may lead to psychological or physical dependency, especially at high dosages.
In one study, 16 people who typically consumed high, moderate or no caffeine took part in a word test after going without caffeine overnight. Only high caffeine users showed a bias for caffeine-related words and had strong caffeine cravings.
Even though the compound does not seem to cause true addiction, 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.
6. High Blood Pressure
Overall, caffeine doesn’t seem to increase the risk of heart disease or stroke in most people. However, it has been shown to raise blood pressure in several studies due to its stimulatory effect on the nervous system.
Fortunately, caffeine’s effect on blood pressure seems to be temporary. Also, it seems to have the strongest impact on people who aren’t used to consuming it. High caffeine intake has also been shown to raise blood pressure during exercise in healthy people, as well as in those with mildly elevated blood pressure.
Therefore, paying attention to the dosage and timing of caffeine is important, especially if you already have high blood pressure.
7. Rapid Heart Rate
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.
If you notice any changes in your heart rate or rhythm after drinking caffeinated beverages, consider decreasing your intake.
Coffee, tea and other caffeinated beverages are known to boost energy levels. However, they can also have the opposite effect by leading to rebound fatigue after the caffeine leaves your system.
One review of 41 studies found that although caffeinated energy drinks increased alertness and improved mood for several hours, participants were often more tired than usual the following day. 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 maximize caffeine’s benefits on energy and avoid rebound fatigue, consume it in moderate rather than high doses.
9. Frequent Urination and Urgency
Increased urination is a common side effect of high caffeine intake due to the compound’s stimulatory effects on the bladder.
In one study, 12 young to middle-aged people with overactive bladders who consumed 2 mg of caffeine per pound (4.5 mg per kilogram) of body weight daily experienced significant increases in urinary frequency and urgency. For someone weighing 150 pounds (58 kg), this would equate to about 300 mg of caffeine per day.
In addition, high intake may increase the likelihood of developing incontinence in people with healthy bladders.
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.