Coffee is something we truly can’t get enough of, but it’s important to remember that it is high in caffeine at around 100mg per 8oz cup. Medical guidelines suggest that a safe daily amount of caffeine is around 400mg, so what happens if you drink too much?

We’ll look through the guidelines in detail and learn how to spot signs that you’ve had too much. We’ll also go over the effects of excessive caffeine consumption, both in the short and long term.

How Much Caffeine Can I Have in a Day?

The US FDA (Food and Drug Administration) recommends a safe limit for adults of 400mg of caffeine per day [1]. Anything above 600mg of caffeine per day is considered to be a high level of caffeine consumption and can lead to health problems if maintained for a long period of time. 

To stick within your daily limit, you can have:

• 4 cups of coffee,
• 8 cups of tea,
• or 2 large energy drinks.

Of course, some drinks may be higher or lower in caffeine, so check the label or packaging if you’re monitoring your daily caffeine count.

Related: How Late Is Too Late for Coffee?

What Does Caffeine Do?

Caffeine is known medically as an “adenosine receptor antagonist.” This means that caffeine inhibits the adenosine receptors in your brain, preventing them from absorbing adenosine, a sleep-promoting chemical [2]. This effect is why coffee and other caffeinated drinks can make you feel so alert and focused, as they block one of the body’s sleeping signals. But there are also cases where caffeine makes them tired.

Other key effects of caffeine include promoting the release of dopamine and helping to boost your mood. Coffee drinkers may also experience decreased appetite as the caffeine works in tandem with chlorogenic acid [3]. Alongside being a key factor in coffee’s taste and aroma, chlorogenic acid is a powerful antioxidant that helps the body get the most out of the food digested, stopping you from feeling as hungry. 

Related: How Long Does Caffeine Last?

Signs You’ve Had Too Much Caffeine

If you have too much caffeine, it can come with some less-than-ideal side effects. Look out for these signs that may indicate you need to lay off the coffee a little bit:

• Increased need to go to the bathroom (caffeine is a diuretic)
• Anxiety
• Increased heart rate/palpitations
• Inability to sleep
• Headaches
• Tremors (“caffeine jitters”)

It’s worth noting that the side effects experienced and their intensity will vary from person to person. Those with a lower caffeine tolerance are much more likely to experience more powerful side effects like headaches and an increased heart rate from less caffeine consumption than those who drink it regularly.

Related: How to Reduce Heart Palpitations from Caffeine

Long-Term Effects of Caffeine Consumption

Occasionally having too much caffeine usually doesn’t carry much risk. But, you need to be careful if you drink a lot of it over a longer period of time, as it may lead to some health issues. These can include: 

• Trouble sleeping or insomnia 
• Weakened bones and muscles, as well as an increased risk of osteoporosis for older women [4,5] 
• Digestion issues from stomach acid levels and lessened appetite. This can lead to a condition called GERD (gastroesophageal reflux disease) [6] 
• High blood pressure
• A faster resting heartbeat [7]

Can You Overdose on Caffeine?

It’s possible to overdose on caffeine, but this usually only occurs from consuming too many foods and drinks that have a very high caffeine amount in a short space of time, like energy drinks and shots or over-the-counter caffeine tablets. 

Caffeine overdose can cause symptoms like:

• Fever
• Rapid heartbeat and high blood pressure
• Muscle tension
• Seizures

In severe cases, it can even be fatal [8].

Don’t panic though! It's important to remember that caffeine overdose and toxicity are extremely rare. But, that being said, if you're experiencing any unpleasant effects from too much caffeine consumption, you may want to ask your doctor or another medical professional for some advice.

What Can I Do to Reduce My Caffeine Intake?

If you feel that you’re drinking too much caffeine and want to cut down, there are some steps you can take to still enjoy the great taste and experience of coffee without triggering its side effects.

• Try a less caffeinated blend: Some drinks contain more caffeine than others, so check the caffeine content of your current drink and try to find a similar alternative that works for you. For example, if you enjoy robusta coffee like Ha Noi or Ban Me which has a naturally high caffeine content, consider switching to a blend of robusta and arabica beans like Sai Gon OG or Da Nang. 
• Try tea: Thanks to the amino acid L-theanine, the caffeine release in tea is slower and more consistent than in coffee [9]. If you find yourself needing to reach for extra caffeine as a pick-me-up throughout the day, then switching to tea could help provide the long-lasting boost you are looking for. 
• Go decaf: If you want to try to wean yourself off of caffeine completely, there are some great decaf options out there. However, if you do this, be aware that decaf still has a small amount of caffeine. Make the switch slowly and gradually, too, to avoid caffeine withdrawal. 
• Try an alternative source of energy: You may want to consider trying a different source of energy and alertness, especially if your body naturally has a low caffeine tolerance. Alternatives to caffeine include ginseng and peppermint. 
• Be mindful of your caffeine intake: A simple way to keep on top of your caffeine consumption is to keep track of how much you're actually consuming. This means reading labels, making a note of the caffeine content, and monitoring your intake. Keeping a diary of your caffeine intake and its effects can help you better understand your tolerance and make the necessary adjustments to your intake.

FAQ: Caffeine Content and Consumption

Have questions about caffeine consumption? We’ve rounded up some of the things you still might want to know. 

1. What drinks are the highest in caffeine?

Coffee is near the top of the list when it comes to drinks with a high caffeine content, with an average caffeine content of 100mg. However, be aware that the caffeine levels of robusta and arabica coffee differ, with robusta beans having more caffeine than the latter.

Some energy drinks have a higher caffeine content still than cofffee, often bolstered by sugar for an extra energy boost, and can have up to 200mg of caffeine per serving. 

2. How do I keep track of my caffeine consumption?

A great way to keep track of your caffeine consumption is to keep a diary of your daily intake and effects. This doesn’t have to be as fancy as keeping a book with you, as even just making a note on your phone can be effective.

Monitoring your coffee consumption can help you determine your caffeine limit, especially if you’re thinking of switching to highly caffeinated beans like Vietnamese coffee for a stronger energy boost.

3. Is decaf coffee healthier for you?

Decaf coffee has exactly the same health benefits as regular coffee, but with less caffeine. It’s important to remember though that decaf doesn’t mean it’s “caffeine-free.” It still has caffeine but is 97% less than its regular counterpart. 

4. What are the side effects of coffee?

The side effects of coffee can include an increased heart rate, anxiety, headaches, and shaking. If you’re experiencing these symptoms, you may want to cut down on your intake. You could also switch to less caffeinated beans Cafely’s Da Lat.

5. How much coffee should I drink?

The medical advice given by the FDA is 400mg of caffeine per day. This equates to around 4 8oz coffees. 

References:

1. USDA. (2015). DIETARY GUIDELINES FOR AMERICANS EIGHTH EDITION. 
2. Ribeiro, J. A., & Sebastião, A. M. (2010). Caffeine and adenosine. Journal of Alzheimer’s Disease: JAD, 20 Suppl 1(20), S3-15. 
3. Rojas-González, A., Figueroa-Hernández, C. Y., González-Rios, O., Suárez-Quiroz, M. L., González-Amaro, R. M., Hernández-Estrada, Z. J., & Rayas-Duarte, P. (2022). Coffee Chlorogenic Acids Incorporation for Bioactivity Enhancement of Foods: A Review. Molecules, 27(11), 3400. 
4. Campana, C., Griffin, P. L., & Simon, E. L. (2014). Caffeine overdose resulting in severe rhabdomyolysis and acute renal failure. The American Journal of Emergency Medicine, 32(1), 111.e3–111.e4. 
5. Berman, N. K., Honig, S., Cronstein, B. N., & Pillinger, M. H. (2022). The effects of caffeine on bone mineral density and fracture risk. Osteoporosis International. 
6. Lohsiriwat, S., Puengna, N., & Leelakusolvong, S. (2006). Effect of caffeine on lower esophageal sphincter pressure in Thai healthy volunteers. Diseases of the Esophagus, 19(3), 183–188. 
7. Riksen, N. P., Rongen, G. A., & Smits, P. (2009). Acute and long-term cardiovascular effects of coffee: Implications for coronary heart disease. Pharmacology & Therapeutics, 121(2), 185–191. 
8. Murray, A., & Traylor, J. (2020). Caffeine Toxicity. PubMed; StatPearls Publishing. 
9. Giesbrecht, T., Rycroft, J. A., Rowson, M. J., & De Bruin, E. A. (2010). The combination of L-theanine and caffeine improves cognitive performance and increases subjective alertness. Nutritional Neuroscience, 13(6), 283–290.