How Much Caffeine Is Too Much?

Most of us enjoy a cup of tea or coffee in the morning, but how much caffeinated goodness is too much?

With over 26,000 coffee shops on UK high streets^[i], high-tech pod machines on many kitchen counters and new tea and coffee trends emerging on the regular, we’re undoubtedly a nation that runs on caffeine.

However, we all know it’s possible to get too much of a good thing, especially when it comes to caffeine intake. Here we answer your burning questions about consuming caffeine and the long- and short-term effects those flat whites are having on your health.

Am I Drinking Too Much Caffeine?

Caffeine tolerance can vary from person to person. However, expert guidelines can help you keep caffeine consumption at healthy levels.

What is the recommended daily dose of caffeine?

The Food Standards Agency (FSA) and Food Standards Scotland (FSS) issued guidance on caffeine consumption in 2024. These expert-informed agencies advise consuming no more than 400mg of caffeine per day^[ii]. This includes caffeinated drinks, foods containing caffeine and caffeine supplements.

Pregnant people should avoid consuming more than 200mg of caffeine each day^[iii]. Meanwhile, industry guidelines set a safe level of caffeine for children at 150mg per day^[iv]. Those with underlying health issues like high blood pressure or heart disease should consult their GP on safe caffeine consumption.

How much caffeine am I really consuming?

How does your favourite caffeinated drink (or snack) stack up?^[v]^[vi]

Item	Average Amount of Caffeine
Brewed coffee (200ml)	90mg
Espresso shot (60ml)	80mg
Decaf coffee (200ml)	4mg
Instant coffee (200ml)	45mg
Black tea (250ml)	28mg
Green tea (250ml)	19mg
Decaf black tea (250ml)	8mg
Matcha (2g)	Up to 88mg
Cola (355ml)	37mg
Energy drink (250ml)	80mg
Dark chocolate (14g or two squares)	7mg
Milk chocolate (14g or two squares)	2mg

Keep in mind too that some treats, such as tiramisu or coffee-flavoured ice cream, may contain an amount of caffeine. Additionally, some supplements and medications, especially energy supplements and cold/flu medications, include caffeine.

Can caffeine tolerance change?

Your tolerance for caffeine can change as your body begins to rely on this natural stimulant. If you’re consuming caffeine regularly, tolerance usually rises, requiring you to drink more coffee or tea to achieve that same alert and awake effect that a single cup once gave you^[vii].

Conversely, some people develop caffeine sensitivity suddenly or over time. Someone with a caffeine sensitivity metabolises caffeine slowly, meaning that symptoms including jitters, insomnia, headaches and a racing heart can last for several hours.

How Does Caffeine Affect My Health?

Caffeine can offer benefits, including improved mental alertness^[viii] and enhanced physical performance^[ix]. It can also impact you negatively...

Will caffeine affect my sleep?

Caffeine is known to affect sleep, as anyone who’s enjoyed an after-dinner cappuccino will tell you. Drink too much caffeine and you might:

Find it more difficult to fall asleep
Get less sleep overall
Sleep less deeply than usual

This is because caffeine blocks adenosine^[x], the hormone that makes us sleepy.

In fact, studies show that drinking caffeine can reduce total sleep time by up to 45 minutes, reduce efficiency of sleep by 7% and delay falling asleep by nine minutes^[xi]. Of course, this can vary depending on how sensitive you are to caffeine’s effects.

Can caffeine cause anxiety?

Caffeine is a stimulant, meaning that it can make anxiety worse, or even trigger anxious feelings^[xii]. Studies show that the risk of caffeine-induced anxiety is higher at doses over 400mg^[xiii] and that too much caffeine may even trigger panic attacks^[xiv].

Why does caffeine make us more anxious? It's mainly due to its ability to block adenosine, that relaxing neurotransmitter. Caffeine also stimulates your central nervous system’s fight or flight response. The raised heart rate and blood pressure of this autonomic response can mimic the doom-laden feeling of anxiety, kickstarting a vicious cycle of actual anxiety.

What are the long-term and short-term risks of caffeine consumption?

Other than the potential for increased anxiety and sleep disruption, possible risks of caffeine consumption include:

Common brief effects, such as headaches, jitters and increased heartbeat^[xv]
Increased blood pressure after consumption^[xvi]
Increased urine production, meaning you’ll need to pee more often^[xvii]
Triggering or new development of IBS symptoms^[xviii]
Negative effect on blood glucose levels and insulin resistance^[xix]
Increased feelings of tiredness after caffeine effects wear off^[xx]
Eventual reduction in exercise performance^[xxi]

Excess consumption over the daily recommendations outlined above is linked to:

Rhabdomyolysis, which can lead to kidney failure^[xxii]
Increased risk of osteoporosis^[xxiii]
Altered gut microbiota and knock-on effects^[xxiv]
Pregnancy loss^[xxv], stillbirth and fetal developmental issues^[xxvi]

Should I Reduce My Caffeine Intake?

Most people without underlying health conditions can safely consume caffeine without risk of harm. However, there are some things to consider:

Am I dependent on caffeine?

Caffeine is such a part of our daily routine that, eventually, most of us become somewhat dependent. In fact, studies show around a quarter of those who use caffeine meet the criteria for dependency^[xxvii].

If you simply can’t manage without coffee, chances are that you’re dependent. And if so, you might experience the following side effects if you don’t get enough caffeine to sustain your body’s need^[xxviii]:

Fatigue and drowsiness
Feeling less alert/brain fog
Trouble focusing on tasks
Reduced energy/sluggishness
Irritability/general grouchiness
Headache
Nausea
Muscle pain/stiffness

These symptoms will usually begin 12 to 24 hours after your last caffeine fix.

Is it possible to overdose on caffeine?

Caffeine overdose or poisoning is entirely possible and very dangerous. This happens when you’ve consumed more caffeine than your body is able to safely process. Though rare, some people suffer from caffeine toxicity when taking an overdose of caffeine supplements or drinking an excess of energy drinks.

Early symptoms of overdose^[xxix] include dizziness, headache, fever, insomnia, diarrhoea and irritability. Later you might begin to vomit, feel confused, hallucinate and experience a racing or uneven heartbeat. Eventually, caffeine overdose can lead to convulsions and shock^[xxx]. In extreme cases, caffeine overdose can result in death^[xxxi].

If you’re concerned that you may have consumed too much caffeine, contact your GP or NHS 111.

How can I reduce my caffeine intake?

There’s not a lot of support out there for those caffeine addicts among us. However, if you’re worried that your caffeine intake is too high there are some things you can do:

Taper your intake slowly: to reduce the risk of withdrawal symptoms like headaches and drowsiness, reduce your caffeine intake little by little. You can do this by reducing by one cup of tea or coffee per week, or by reducing the size of your cup until you’ve reached your target.

Replace with non-caffeinated alternatives: often drinking tea or coffee is as much about the ritual as it is the caffeine. Try substituting with herbal tea or low sugar soft drinks at the same times and taking the same break that you’d enjoy when consuming your cuppa.

Drink plenty of water: caffeinated drinks count towards your must-have daily intake of water. Therefore, it’s important to replace that fluid to stay hydrated and minimise headaches. Pick up a reusable water bottle to ensure reliable hydration on the move.

Summary

Drinking caffeine is safe for most people, provided you stay within the recommended daily amount of 400mg per day. Indulge over that and you might experience physical and mental side effects, with some potential for long-term damage. In particular, sleep can be affected.

Some people can become dependent on caffeine and find it hard to function without it. If this sounds like you, it might be a good idea to reduce your intake.

[i] https://www.teaandcoffee.net/blog/36125/the-uk-branded-coffee-shop-market-continues-to-rebound/#:~:text=Yet%2C%20despite%20short%2Dterm%20apprehension,next%203%2D5%20years.%E2%80%9D

[ii] https://www.food.gov.uk/news-alerts/news/fsa-and-fss-issue-guidance-on-caffeine-in-food-supplements

[iii] https://www.food.gov.uk/news-alerts/news/fsa-and-fss-issue-guidance-on-caffeine-in-food-supplements

[iv] https://www.bbc.co.uk/news/uk-scotland-23036474

[v] https://www.eufic.org/en/?ACT=115&path=global%2Fpdf%2Fcaffeine-levels-in-different-foods-and-drinks&size=Letter&orientation=portrait&key=&attachment=1&compress=1&filename=caffeine-levels-in-different-foods-and-drinks.pdf&default_font=

[vi] https://www.bbc.co.uk/bitesize/articles/zdt8vj6#ztb68p3

[vii] https://www.ncbi.nlm.nih.gov/pubmed/6298543

[viii] https://www.ncbi.nlm.nih.gov/books/NBK209050/

[ix] https://www.healthline.com/nutrition/caffeine-and-exercise

[x] https://pmc.ncbi.nlm.nih.gov/articles/PMC9541543/

[xi] https://pubmed.ncbi.nlm.nih.gov/36870101/

[xii] https://pmc.ncbi.nlm.nih.gov/articles/PMC10867825/