Caffeine is a central stimulant, i.e. it stimulates the brain. Caffeine is present in coffee, tea and cola drinks etc.

^{Updated 9.11}

• Hide this answer

Drinking tea and coffee is a common social activity as well as being many people's main fluid intake during a day. Moderate amounts of caffeine, i.e. 250-500mg per day, are thought to be harmless, unlike alcohol and nicotine, which have definite serious adverse effects. Indeed, it has been considered that most of the country would not operate properly without caffeine! Higher amounts of caffeine can, however, have noticeable unwanted effects.

^{Updated 9.11}

• Hide this answer

"Caffeinism" is the term used for people who are dependent upon caffeine i.e. suffer side effects from having too much caffeine, take larger amounts and need to keep drinking caffeine to function properly (including a "craving" feeling for caffeine). "Caffeinism" is thought to occur if you have an intake of above 600mg to 750mg of caffeine per day. Drinking more than 1000mg per day is well into the toxic range. The US Olympic Committee considers caffeine a stimulant and has an upper limit for caffeine levels in the blood, above which an athlete "fails a drugs test".

People may drink large quantities of tea, coffee and cola drinks to relieve thirst or dry mouth caused by side effects of drugs, such as some antidepressants and antipsychotics. Since headaches can occur when caffeine is stopped, drinking caffeine stops these headaches occurring.

^{Updated 9.11}

• Hide this answer

The symptoms of caffeinism can include feelings of anxiety and nervousness, sleep disruption (especially difficult getting off to sleep), restlessness, irritability, diuresis (passing lots of water/urine), stomach complaints, tremulousness, palpitations and arrythmias (changed heart rate, especially faster beating). 150mg of caffeine at bedtime has been shown to have a marked effect on how long it takes to get to sleep, reduce total sleep time, the quality of sleep and REM (dreaming) periods. Caffeinism can make some illnesses such as anxiety more resistant to drug treatment. People who suffer from panic attacks may be more sensitive to the stimulant effects of caffeine.

Suddenly stopping taking caffeine can produce problems. Withdrawal from even moderate amounts of caffeine can produce headaches (52%), anxiety (10%), rebound drowsiness, fatigue and lethargy, with many other effects reported.

"Caffeinism" is considered a drug addiction and caffeine withdrawal syndrome is a documented condition.

^{Updated 9.11}

• Hide this answer

You can work out your daily intake of caffeine using this table:

There can be a wide range of caffeine in tea, depending on the type and for how long it is brewed. Contents can range from 40mg/mug through to as high as 130mg/mug in extreme cases.

^{Updated 9.11}

• Hide this answer

If you are taking more than about 600-750mg a day of caffeine, you might feel better if you took less caffeine, especially if you are anxious, don't sleep well or suffer panic attacks. Many people seem to be able to function well on higher levels than this. However, since caffeinism can be considered a drug "addiction", stopping caffeine suddenly is not a good idea as withdrawal effects (see previous page) are likely. The best plan for someone who may be drinking too much caffeine is to gradually reduce this to a safer level, preferably over several weeks.

You can reduce your intake in many ways e.g.:

    •    Use decaffeinated (or at least instant) coffee and/or tea sometimes

    •    Avoid brewed coffee or strong tea

    •    Mix decaffeinated coffee powder with ordinary coffee powder to make a lower-caffeine drink

    •    Either drink smaller volumes of coffee or tea or make the drinks weaker

    •    Drink caffeine drinks less often

    •    Do not drink too many cola drinks e.g. Coca-Cola, Pepsi etc

One useful plan is to start with one or two decaffeinated drinks per day. Then increase this gradually e.g. alternating decaffeinated drinks with ordinary caffeine-containing drinks. Avoid taking caffeine drinks within a couple of hours of going to bed. .

^{Updated 9.11}

• Hide this answer