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coffee; drug; stimulant; cola; chocolate; caffeine; tea; pregnancy; decaffeinated; withdrawal; guarana; guaranine; energy;


We all know caffeine is that stuff in coffee; some of us even think caffeine is coffee!! This is your opportunity to find out more about what you are drinking, how much is enough and what it does for you.

What is caffeine?

Caffeine is a chemical found in many different plants from all over the world and it is a stimulant to the brain and nervous system. ('Stimulant' means that it speeds up the brain and nervous system).

Here are some of the plants it can be found in:

  • the coffee bean originally from Arabia
  • the tea leaf from China
  • the kola nut from West Africa
  • the cocoa bean from Mexico
  • the ilex plant from Brazil
  • the Cassina tree (or Christmas berry tree) from North America.

These plants are now grown elsewhere in the world and are no longer confined to their countries of origin. Extracts from these plants are used in many foods and drinks, such as tea, coffee, chocolate and cola flavoured drinks.

The history of caffeine

Caffeine has been used as a stimulant for a very long time, since the Stone Age in fact. It is recorded that tea drinking was taking place in 2737 BC, coffee drinking in 1000 AD and milk chocolate bars in 1876.

The health effects of caffeine have been studied a lot.

How much caffeine do we consume?

Obviously this depends on you and your personal diet - you may not consume any caffeine. However, of all caffeine consumed in the world, 54% is from coffee, 43% from tea and the other 3% from other sources (such as cola and medications). There is no doubt that the majority of caffeine in a child's and many young people's diets comes from cola and 'energy' drinks.

The effects of caffeine

The main effect of caffeine is that it stimulates the central nervous system.

With small amounts:

  • you feel more awake
  • your heart beats faster
  • your blood pressure rises
  • you pass more urine
  • you make more stomach acid.
Larger amounts:
  • anxiety and restlessness
  • headaches
  • difficulty getting to sleep,
  • very large amounts can cause confusion and sometimes hallucinations.

Long-term effects

If you have more than 600 mg of caffeine a day for a long time you may:

  • find it difficult to sleep
  • worry a lot
  • be depressed
  • have stomach upsets.

Caffeine and sleep

If you have caffeine before you go to bed it usually:

  • makes it harder to go to sleep
  • makes you sleep for a shorter time
  • shortens the amount of deep sleep and 'dream' sleep you have - so that you do not feel so rested when you wake up.

How much caffeine is in what?

These are approximate levels only. The amount depends on how the drink is made, what it is made from and how strong it is. (Tea and coffee is measured in "average" cup size.)


  • Filtered coffee (250ml)           200 - 250mg of caffeine.
  • Percolated coffee (250ml)       100 - 150mg of caffeine.
  • Instant coffee (250ml)            80 - 150mg of caffeine.
  • Decaffeinated coffee (250ml)   4 - 8mg of caffeine.


  • Tea (250ml)          20 - 200mg of caffeine (usually 20 - 50mg)
  • Iced Tea (350ml)   12 - 28mg of caffeine

Other drinks and chocolate

  • Cola drinks (350ml)       30 - 72mg of caffeine (High caffeine drinks will have more caffeine).
  • Energy drinks                150mg or more
  • Hot chocolate                 10mg of caffeine.
  • Chocolate bar (200gms) 60 mg of caffeine.

How much caffeine is too much?

It is difficult to say exactly how much is too much because we are all individuals and will have different reactions and responses from particular foods or substances. Some people seem to be able to tolerate much more caffeine than others. However, 250mg (approximately) will probably cause some mild effects and 750mg will probably produce more severe effects for most people.

If you notice any of the following happening to you (and you have a relatively high intake of caffeine) it may be wise to reduce your intake levels.

  • irritability
  • headaches
  • tiredness
  • confusion
  • agitation
  • sweating
  • anxiety
  • insomnia
  • fast, irregular heart beat.

Most researchers say that there is very little health risk for people who consume less than 600mg per day. However, if you are under stress, suffer anxiety or are pregnant then doctors recommend less than 200mg per day.

Caffeine and pregnancy

A lot of research has been done about the safety of caffeine during pregnancy. It appears that drinking a 'normal' amount of caffeine during pregnancy does not harm a developing baby. However, drinking a lot of caffeine can make it harder to get pregnant and there seems to be a higher risk of miscarriage.

It is recommended that pregnant women do not have more than 200 mg of caffeine a day.This may be four cups of tea, or two cups of coffee, or even one cup of coffee if it is very strong coffee.


  • Guarana is a plant growing in South America (especially Brazil). Guarana contains guaranine which is the same as caffeine.
  • Each guarana bean contains an amount of guaranine which is equivalent to about 3 times as much caffeine as a coffee bean.
  • Drinks containing guarana often contain a lot of guaranine and the effects are the same as drinking a lot of caffeine.

Caffeine withdrawal

If you decide that you are consuming too much caffeine, you could start cutting down or even stop all together! Because people become dependent on caffeine, you may experience some withdrawal symptoms if you have been used to receiving your regular 'dose' for sometime and if you stop all at once. Some of the withdrawal symptoms include:

  • irritability
  • headaches
  • tiredness
  • feeling sick
  • general aches and pains.

If you are having trouble with stopping taking caffeine, talk to a drug counsellor or a health worker. If you do not have a high caffeine intake and you experience any of these symptoms it is important to seek medical advice.

Caffeine and exams 

  • A small amount of caffeine, such as the caffeine in one cup of coffee or tea seems to help many people to 'perform' better than no caffeine. It has been shown that people who have a cup of tea or coffee to start the day, do not manage so well if they miss that drink.
  • Large amounts of caffeine may make a person feel more awake (or stop them falling asleep), but there is not an improvement in performance. In fact the anxious feelings due to the caffeine may make them do worse than usual.

Resources in South Australia

South Australia

  • The Youth Health Service
      - Central: 57 Hyde St, Adelaide
      - South: 50a Beach Rd, Christies Beach
      - North: 6 Gillingham Rd, Elizabeth
      - West: 51 Bower St, Woodville
  • Alcohol and Drug Information Service (ADIS 24 hour statewide line in South Australia) 1300 131 340


Drug Info Clearinghouse - Australian Drug Foundation Fact sheet 'Caffiene'. 

National Drug and Alcohol Research Centre Fact sheet 'Caffeine'

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The information on this site should not be used as an alternative to professional care. If you have a particular problem, see a doctor, or ring the Youth Healthline on 1300 13 17 19 (local call cost from anywhere in South Australia).
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