How much coffee is too much?

Whether you crave the smell of fresh coffee, drink it for the taste or simply like the occasional pick-me-up, our love affair with coffee is stronger than ever. Over 60% of Australian adults consume coffee and coffee substitutes, and is the second most popular non-alcoholic beverage after water.¹

For most healthy adults, around 400mg of caffeine a day – roughly 2 espressos – is generally considered safe. But how much coffee is too much depends on your body and life stage. Drinking more than this may lead to side effects like jitteriness, poor sleep, headaches or a racing heart. Understanding your personal tolerance is key to enjoying coffee without the downsides. We spoke to Medibank Group Medical Director, Dr Shona Sundaraj about enjoying coffee safely, signs you might be overdoing it, the possible health risks, and who may want to consider cutting back.

How much caffeine is in a cup of coffee?

With so many ways to source and brew coffee, the amount of caffeine in each cup can vary. 

Here’s a guide:
 

There’s also caffeine found in other beverages and food: 
 

What's the safe daily caffeine limit?

The safe daily caffeine limit depends on your age and life stage.
 

• Healthy adults: 400mg per day
• Pregnant or breastfeeding: 200mg per day
• Adolescents aged 14-17: 100mg per day

For adolescents under 14 years old, no caffeine consumption is recommended.

Dr Sundaraj explains there is some nuance to the ‘right’ amount of caffeine, though.

“It dependent on the size of the person and their ability to metabolise the caffeine as well,” she says.

Signs you’re drinking too much coffee 

Like any stimulant, consuming too much can have a negative impact on your body. 

These are some of the side effects of too much caffeine: 
 

• Dehydration
• Dizziness
• Headaches
• Heart palpitations
• Trembling hands
• Sleeplessness
• Irritability and anxiety.
  

Dr Sundaraj explains “symptoms are not typically experienced by people that regularly drink coffee, [but] they can certainly happen in people that are naive to drinking coffee or caffeine containing substances.”

Energy drinks can be especially problematic because they contain both a high level of caffeine and sugar, says Dr Sundaraj.

“Some of them have three to five times the recommended dosage of caffeine per day and we find that young people in particular are quite vulnerable to these types of effects.”

Caffeine, anxiety and sleep

Dr Sundaraj highlights anxiety and sleeplessness as two of the major long-term health effects of caffeine overconsumption.

Caffeine works by blocking adenosine receptors in the brain. When the brain doesn’t perceive adenosine, it keeps releasing chemicals that keep you awake.

Research² shows when and how much caffeine you consume in a day can affect your sleep differently. A 100mg dose of caffeine (about 1 cup of instant coffee) can be consumed up to 4 hours prior to bedtime, but 400mg consumed as a single dose (about 1 double espresso) within 12 hours of bedtime may negatively impact sleep.

The same mechanism that blocks adenosine receptors causing sleep disruptions, can also contribute to feelings of anxiety.

According to results of a meta-analysis summarising the evidence about the association between caffeine intake and risk of anxiety³, caffeine consumption may not only have a detrimental effect on anxiety, but it may also increase the risk of anxiety. This relationship was stronger at caffeine intake levels exceeding 400mg.

Dr Sundaraj explains it can be hard for people to recognise coffee (or other caffeinated food and drinks) as a contributor to their sleep or anxiety issues because they may have been consuming it for a long time.

“Lifestyle measures when someone is experiencing anxiety or insomnia are really important – I can't overstate the importance of that and reducing the amount of stimulant, so the amount of caffeine, as a way to control anxiety and to get better sleep,” says Dr Sundaraj.
 

READ MORE: Your sleep hygiene checklist for a better night's rest

Who should drink less coffee?

According to Dr Sundaraj, some people should reduce their caffeine intake, if they are:
 

• sensitive to caffeine
• pregnant or breastfeeding
• experiencing anxiety
• experiencing sleep issues.

And there are some people who should avoid caffeine consumption altogether.
 

• People with blood pressure that’s not well controlled
• People with heart rhythm abnormalities that’s not well controlled
• Children.
   

READ MORE: Dealing with fatigue during pregnancy

Can you build a tolerance – and how to cut back?

You can build up a tolerance to caffeine, meaning you may find yourself increasing the number of cups you’re consuming to feel the positive side effects.

Here are some tips for finding balance and developing healthier coffee habits. 
 

• Set a coffee curfew: Decide how late your last coffee of the day will be, and stick to it so that your body can get into a routine. If you’re struggling to fall asleep, it might be best to avoid coffee after lunch.
• Forgive the fraction: Ask for a three-quarter shot if you’re trying to cut down on caffeine. Try playing with milk-to-coffee ratios as well.
• Combine your caffeine quota: Chances are that coffee is not your only source of caffeine. Don’t forget to consider the caffeine you might be getting from other sources, like tea, chocolate, cola and energy drinks.
• Phase out the sweet stuff: If you’re adding sugar, you’re not only adding calories but you could be missing that pure coffee flavour. Try gradually scaling back the sugar by a small amount every few days - this will allow for a much healthier routine.
• Withdraw slowly: If you build up a tolerance for caffeine, you can become dependant on coffee to function effectively. The best way to reverse this trend is to cut down gradually, giving your nervous system time to adjust - physically and psychological - without it.

If you love your coffee, there are many healthy ways to enjoy it. Stick to the recommended limits and be aware that everyone will respond to caffeine differently, so think of your body (and mind) as the best measure of what works for you.

Frequently asked questions

What is the best way to reduce coffee consumption?

It’s recommended you cut back on your coffee gradually rather than going cold turkey. This will help minimise potential withdrawal effects from the caffeine and allow your body (and habits) to adapt without it.

What are the symptoms of coffee withdrawal?

Withdrawal symptoms vary, but can include fatigue, crankiness, a persistent headache, sweating, muscle pain, and sometimes anxiety. Withdrawal symptoms may begin within 12-24 hours and can last approximately 7 days.

Can drinking coffee affect your medication?

Consuming caffeine with some medications, may increase certain side effects. On the other hand, caffeine can reduce the effectiveness of other medications. It’s aways best to discuss your caffeine habits with your prescribing doctor.

Does decaf coffee have caffeine?

A 250mL cup of decaffeinated coffee has approximately 2-6 mg of caffeine.

Does chocolate have caffeine?

A 50g bar of milk chocolate has approximately 10mg of caffeine.