Causes And Effects Of The Caffeine Overdose: Some Basic Facts And Figures

by | Aug 26, 2019

I don’t know about you, but if I drink more than a few cups of coffee a day I sometimes find myself wondering about caffeine and its effects. I’ve been especially interested recently in how much caffeine is a “safe” amount. So I thought I’d dig into things a little more deeply, to put my mind at rest.

The scientific name for caffeine is 1, 3, 7- trimethylxanthine, but somehow that doesn’t trip off the tongue as well as “caffeine”. Caffeine occurs naturally in some nuts, plants and seeds and is, in fact, a toxin: some plants use this substance as a defense mechanism. In small amounts, however, caffeine is beneficial to (most) humans. Recent research even shows it can help some serious health conditions.

What Is Caffeine? Is Caffeine a Drug?

For most Americans, coffee is the number one source of caffeine, although it is also found in tea and other specialized regional drinks like mate in Argentina, in some sodas, soft drinks, and guarana. There are also a few surprising sources of caffeine, including chocolate, cocoa, mocha ice cream and kola nuts.

The amount of caffeine in drinks varies. An average 8 fluid ounce cup of caffeinated coffee usually contains around 100 milligrams of caffeine. A 12 fluid ounce can of soda such as cola incorporates around 35 to 45 milligrams of caffeine; an 8-ounce energy drink has in the region of 75 to 100 milligrams, and an 8-ounce cup of tea around 14 to 60 milligrams.

While decaffeinated coffee is much lower in caffeine, it still contains some caffeine – around 7 milligrams.

Caffeine is available in other forms, including tablets and powders, and is sometimes found mixed in with more harmful substances.  It is also found in some painkillers and cold and flu medications that can be purchased over-the-counter in several countries.

A fairly recent development is the production of anhydrous caffeine, a dehydrated supplement used in some parts of the athletic community and by those seeking weight loss. Energy bars and caffeinated gum may also contain this substance, which is considerably higher in caffeine content than your average cup of coffee.


How Likely Is A Caffeine Overdose?

General nutritional advice is that 400 milligrams or less of caffeine a day provide a safe “serving” for most people. Since there are around 100 milligrams of caffeine in the average serving of ordinary strength coffee of around 8 fluid ounces, most of us can drink around 4 cups of coffee a day quite safely.

Obviously, if you’re drinking larger servings, say around 12 fluid ounces, then that’s just over 3 cups of coffee. The strength of the brew makes a difference as well.

In recent years, there have been occasional accounts of people overdosing on caffeine. This isn’t a common occurrence, however, and in most cases, where we hear about caffeine overdose, it doesn’t involve people just enjoying a few cups of coffee a day.


We know that children and adolescents have a lower tolerance for caffeine. Around the world, most countries issue official advice that caffeine is not recommended for minors. In those countries where children do regularly drink coffee, such as Finland, the blends consumed are often very mild.

What’s rather more likely to cause a caffeine overdose or even a caffeine intoxication is when something like an energy drink comes into play. We know that many “power” drinks or “energy” drinks have very high levels of caffeine although exact figures are elusive. In recent years, some of the other caffeinated products that are often aimed at athletes also have very high levels of caffeine.


How Serious Is A Caffeine Overdose?

While you would need to ingest seriously high levels of caffeine for it to seriously affect you, caffeine overdoses can be serious, and in some very rare cases, fatal. For some of those who realize they may have overdosed on caffeine, and seek medical help quickly, while the effects have still been serious, they have been stabilized.

Doctors have encountered some individuals who have ingested 5,000 milligrams of caffeine, over 12 times the maximum suggested “safe” amount. Those individuals have experienced for themselves just how serious such a caffeine overdose can be. This is particularly the case if such highly caffeinated products are mixed with alcohol or other substances.


Caffeine Overdose Symptoms

For those of us who aren’t qualified healthcare professionals, initial symptoms might include anxiety, stress or anger, and some of those in the 12 to 18 age range have reported headaches, difficulty with getting their breath, and needing to urinate very frequently. If you have overdone it on the caffeine, you might also experience nervousness, insomnia, sweating, digestive disturbances, fidgeting, and anxiety.

caffeine insomnia

If you’re able to get the individual to a physician, and tests can be run, electrocardiograms, blood gas tests, and other lab tests can confirm whether there has been a caffeine overdose – although for some of these analyses the clinicians do need to know that’s the substance they’re testing for.

What are the symptoms of too much caffeine? Other symptoms of potential caffeine overdose may include seizures, especially recurrent ones; psychosis; renal failure; or tachycardia. Again, for most of these, you’re going to need a healthcare professional to confirm the diagnosis.


Causes And Risk Factors Of Caffeine Overdose

Risk factors for caffeine overdose are very low for most adults. The risks increase for those who take concentrated caffeine tablets, caffeine powder or other products intended to enhance or prolong athletic performance or bring on weight loss.

Certain groups are thought to be particularly at risk of caffeine overdose, and they are athletes, infants, and some psychiatric patients. When clinicians studied 92 deaths from caffeine overdose over several years, they found that people in these categories were most at risk, and even in these cases, many of the deaths were thought to be accidental.

Before 2004, caffeine was one of the substances on the WADA Prohibited List, due to the fact it can enhance performance. It was removed from the World Anti-Doping Agency list after this date but is still monitored by the organization. The NCAA, the National Collegiate Athletic Association, also continues to monitor caffeine levels in athletes.

The average bloodstream concentration of caffeine for those within the daily “safe” limits is around 15 micrograms per milliliter, so anything over this is cause for concern.

For psychiatric patients, it has been found that caffeine interacts with some medications, although as yet the evidence for some of this is not extensive. Where caffeine overdose has been reported in infants, this has usually been linked to deliberate poisoning.

If you suffer from some gastrointestinal disorders, if you’re expecting a baby, or if you’re a new mom and you’re breastfeeding, it’s as well to check with your healthcare professional to make sure you’re okay to enjoy an occasional cup of coffee. The same advice applies if you have heart issues, migraines, anxiety, or high blood pressure, And the official advice is that those under 18 should really stay away from caffeine, pretty much.


How Long Does Caffeine Stay In Your Body?

One of the easiest ways to describe how long caffeine stays in your body is to talk about its “half-life”. If you drink a small cup of coffee, containing around 40 milligrams of caffeine, after 5 hours, there will still be 20 milligrams of caffeine in your system. You get the first “hit” of caffeine sometime between 15 and 45 minutes after you’ve ingested it.

Now I know how much caffeine in decaf coffee

If you’re wondering how long it takes for the effects of caffeine to wear off completely, well, that’s not quite so easy to answer, as it depends on so many factors. These include how much caffeine you’ve consumed, your age, your body weight, and your tolerance to the substance.

Someone who only occasionally drinks a cup of strong espresso, for example, may find that the effects of the beverage take a lot longer for their body to work through than someone who drinks two or three cups of coffee every day. Typically, however, you’re likely to still be feeling some of the effects of caffeine up to four to six hours after you’ve taken it.


How Much Caffeine Is Deadly?

We’ve become so used to caffeine in its usual forms of coffee, tea, chocolate, cocoa, and other drinks being generally very safe that it’s easy to become blasé about the caffeine powders, tablets and other forms out there. For caffeine to prove fatal, most people would need to take in extremely large amounts.

From a positive viewpoint, the new forms of anhydrous caffeine make it easier to standardize the amounts of caffeine you’re taking in. Unfortunately, since many people don’t realize just how concentrated this form of caffeine is, it also means it’s very easy to overdose if you don’t keep a careful eye on the amounts you’re ingesting.

The FDA and many other dietary organizations and advice bodies around the world suggest that a limit of 400 milligrams of caffeine is a safe amount for most adults. So if you’re drinking three or four average-sized cups of coffee a day, and you don’t have any underlying health problems that might be an issue, and you don’t fall into any of the “risk” groups, you should pretty much be okay.


How Much Caffeine Is Safe Then?

The FDA warns against the new types of ultra high-caffeine coffee powder and supplements, however. Just one teaspoon of pure powdered coffee can contain around the same amount of caffeine as 28 cups or even more of ordinary brewed coffee.

In blood tests, concentrations of 15 micrograms per milliliter of blood are what scientists would expect to see for those staying within FDA-recommended suggested caffeine limits. Where deaths have occurred due to high levels of caffeine these amounts have mostly been 100 micrograms or higher, although in at least one reported case the amount was 70 micrograms.


Caffeine Overdose – Conclusion

So can you overdose on caffeine? The simple answer is yes, and, in very rare cases, deaths do occur. Risk factors can include age, medication, how accustomed we are to drinking coffee, and whether there are any existing health conditions or contraindications.

The highest risk factor for death, however, is the amount of caffeine. With very highly caffeinated products, such as anhydrous caffeine, the risks can be high if the recommended “safe” limits are exceeded.

In most cases, however, if we’re sensible about how much coffee we drink, we can still enjoy that morning, mid-morning or mid-afternoon fragrant brew without worrying whether we’re drinking too much.

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