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The effects of caffeine on your health

Updated: Jan 7, 2022

Do you depend on your morning coffee or an energy drink to get you through the day? Mixed messages about caffeine are prevalent in the media, with some sources celebrating it and others criticising it. So, what are the effects of caffeine on your health, and are they good or bad?

What is caffeine and where is it found?

Caffeine is a chemical that is found naturally occurring in some foods and drinks, and is added to others because of its stimulant effect. Most people will know that it is found in coffee, tea and energy drinks, but it’s found in other less well-known places too:


How much

Caffeine content (approx.)


​1 cup instant



1 cup


​Energy drink

1 can 500ml


Cola/caffeinated fizzy drinks

1 can 330ml


Milk chocolate

45g bar


Dark chocolate

45g bar


Guarana seeds

​Varies - ground and added to products

4x as much caffeine as coffee beans

​Supplements / caffeine tablets

Varies between brands

​Usually range from 50mg - 200mg per tablet

Medication e.g. cold and flu tablets



Decaffeinated drinks

1 cup

Trace amounts - unlikely to have stimulating effect

A woman sits in a coffee shop news to a window holding a takeaway coffee cup.
Caffeine can have different effects on different people, and some are more sensitive to it than others.

Is caffeine good or bad for your health?

The 'good' side

  • Alertness – Caffeine stimulates your nervous system and can help improve alertness and concentration.

  • Lower risk of Parkinson’s disease – Early studies have suggested a link between higher caffeine intake and a reduced risk of Parkinson’s disease.

  • Prevent liver disease – There is a consistent association between coffee and reduced risk of liver damage which is thought to be because of its caffeine content.

  • Reduce your risk of gallstones – Research suggests that coffee consumption may significantly reduce your risk of gallstones due to the effect of caffeine on your body.

  • Improve breathing – Caffeine helps to slightly open the airways in the lungs for up to four hours. This can improve your lung function, but also means people with asthma should avoid it before asthma reviews as it could make your breathing appear better than it actually is.

The 'bad' side

Caffeine can have different effects on different people, and some are more sensitive to it than others.

  • Heart palpitations - Those sensitive to caffeine may experience heart palpitations (feeling your heart pounding or fluttering) in which case it’s wise to avoid or limit your intake of caffeine.

  • Heightened anxiety - If you have an existing anxiety disorder, consuming too much caffeine could lead to overstimulation and bring on the symptoms such as increased heart rate and nervousness.

  • Poor sleep - Caffeine can negatively affect your sleep quality and your ability to get to sleep, particularly if consumed later in the day.

  • Bladder irritation – Caffeine can irritate the bladder causing you to need to go to the toilet more frequently. It can also make incontinence worse for people who already suffer from it.

  • Toxic in high doses - Caffeine can be fatal if too much is consumed at once, however to reach this point you would need to consume over 10 grams (or 167 cups of instant coffee or 59 cans of energy drink) in a short space of time. You can still get caffeine toxicity by consuming 1.2 grams or more in one dose (20 cups of coffee / 7 energy drinks), and experience unpleasant side effects such as convulsions and vomiting.

How do you take yours?

It’s often what you consume with caffeine that has the biggest negative impact on your health. Adding sugar, syrups and cream to your coffee will increase the saturated fat content and might boost one cup up to as much as 500 calories. In contrast, an unsweetened black coffee, or one with skimmed milk will have far less fat and may come in at 2 – 20 calories depending on the milk content. That’s a huge difference.

In short, caffeine itself isn’t inherently good or bad, and it can have both positive and negative effects on your health. Like everything, moderation and common sense are key, as well as paying attention to your own body and how it responds to caffeine. If you’re concerned about the effect of caffeine on your health, speak to your GP who can offer specific advice based on your health and circumstances.


Other sources linked within article.


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Please note the date of last review or update on all articles. No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.

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