What is caffeine?
Caffeine is a stimulant drug, which means it speeds up the messages travelling between the brain and the body. It’s found in the seeds, nuts and leaves of a number of different plants, including:
- Coffea Arabica (used for coffee)
- Camelia sinensis (used for tea)
- Cola acuminate (used as a nut, tea or in soft drinks including cola)
- Theobroma cacao (used in cocoa and chocolate)
- Paulinia cupana (used as guarana in snack bars and energy drinks)
How is caffeine used?
Caffeine is used in a number of different products. The amount of caffeine in these products can vary dramatically, so it’s always best to check the label. The average amounts are listed below.
Product Average caffeine content (mg/100 ml)
Red Bull® 32.0
Mountain Dew® 15.0
Coca Cola® 9.7*
Diet Coke® 9.7*
Coke Zero® 9.6*
Brewed black tea 22.5
Brewed green tea 12.1
Coffee, cappuccino 101.9
Coffee, flat white 86.9
Coffee, long black 74.7
Coffee, from ground coffee beans, espresso style 194.0
Chocolate, milk with added milk solids 20.0
Chocolate, dark, high cocoa solids 59.0
Effects of caffeine
There is no safe level of drug use. Use of any drug always carries some risk. It’s important to be careful when taking any type of drug. Caffeine affects everyone differently, based on:
- Size, weight and health
- Whether the person is used to taking it
- Whether other drugs are taken around the same time
- The amount taken
The following effects may be experienced between 5 to 30 minutes after consuming caffeine, and may continue for up to 12 hours:
- Feeling more alert and active
- Restlessness, excitability and dizziness
- Anxiety and irritability
- Dehydration and needing to urinate more often
- Higher body temperature
- Faster breathing and heart rate
- Headache and lack of concentration
- Stomach pains
- Children and young people who consume energy drinks containing caffeine may also suffer from sleep problems, bed-wetting and anxiety.
If a large amount of caffeine is consumed it could also cause an overdose. If you experience any of the following effects, talk with your doctor straight away.
- Nausea and vomiting
- Very fast and irregular heart rate
- Confusion and panic attack
It’s possible to die from having too much caffeine, but this is extremely rare. This would usually only happen if 5–10g of caffeine (or 80 cups of strong coffee) were consumed one after the other.
In small children, caffeine poisoning can happen if a lower amount, such as around 1g of caffeine (equal to around 12 energy drinks) is consumed one after the other.
Some people consume drinks with caffeine so that they can continue working or studying at night. However, the after-effect is that they will feel tired and lethargic the next day.
Regular, heavy use of caffeine (such as more than 4 cups of coffee a day) may eventually cause:
- High blood pressure and heart disease
- Difficulty sleeping
- Infertility (in men and women)
- Needing to use more to get the same effect
- Dependence on caffeine
- Using caffeine with other drugs.The effects of taking caffeine with other drugs – including over-the-counter or prescribed medications – can be unpredictable and dangerous, and could cause:
- Caffeine + alcohol: causes enormous strain on the body, and can mask some effects of alcohol such as falling asleep, leading to drinking more and risk taking behavior.
- Caffeine + other stimulant drugs: increase the risk of cardiovascular problems.
Giving up caffeine after using it for a long time is challenging because the body has to get used to functioning without it. Withdrawal symptoms usually start within 24 hours after the last dose – or even within 6 hours for people who consume a lot of caffeine regularly. The symptoms can last for around 36 hours, or even longer for people who consume a lot.
These symptoms can include:
- Muscle pains
- Anxiety and tension
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