What is caffeine?


Caffeine is a drug that is found in tea, coffee, cocoa, many soft drinks such as colas and some chocolates. It is also used in a wide variety of medicines especially cold remedies.

Caffeine can be manufactured in a laboratory but it mainly comes from the Arabian coffee shrub, commercial tea plants, cocoa beans and kola nuts. Coffee is grown in many areas of the world including Africa, Arabia, Central and South America, Java and Sumatra and the West Indies. Tea is mainly grown in eastern Asia and South America especially India, China, Indonesia, Sri Lanka and Japan. Most of the world’s cocoa is grown in West Africa.

On average in the UK, we drink nearly 100 million cups of tea per day, each cup containing about 40mg of caffeine, but more if the tea is left to brew longer.

Coffee is almost as popular with 95 million cups of coffee consumed a day. About 80% of coffee drank at home is instant coffee containing around 60mg of caffeine per cup.


Tea and cocoa have been drunk for thousands of years. Earliest use of tea was coffeeprobably in China before the 10th century BC. Coffee use is much more recent and the first record of its cultivation was in Arabia about 675 AD. Tea was first imported to Europe in about 1600 by the Dutch East India Company and first came to the UK in about 1660.

Coffee was first introduced to the UK as a medicine but became very fashionable to drink in the 1670s. Coffee houses sprang up in London. They attracted literary figures such as Hogarth and Swift, political revolutionaries and financial entrepreneurs – some of the first banks and the Stock Exchange were started in coffee houses. Coffee houses caused much controversy. The authorities saw them as recruiting places for political radicals and women’s groups protested that they damaged family life. The authorities moved to close down all the coffee houses in London. A compromise was reached where coffee houses could remain open so long as they did not allow the sale of political books and pamphlets or political speeches.

Coffee houses became less popular and changes in commerce saw coffee consumption fall. England turned to tea drinking and remains the only country in Europe that consumes more tea than coffee. In recent years concerns about the effects of caffeine have led to the manufacture of decaffeinated coffees and teas. Roasted coffee beans.

The law

There are no legal restrictions on the sale or use of coffee, tea, cocoa, soft drinks and chocolate confectionery. Certain medicines which contain caffeine may only be available on a doctor’s prescription.


Caffeine is an ‘upper’ and helps stimulate the body, increasing heart rate and blood pressure. It combats tiredness and drowsiness and makes people feel more alert and able to concentrate. Many people have a cup of tea or coffee every morning to ‘get going’. However, people also drink tea and coffee to help them relax. Caffeine also makes people urinate more. High doses can result in people having headaches and feeling very irritable.

People who drink more than 6 to 8 cups of normal strength tea or coffee a day usually become dependent.

They may find it difficult to stop using and experience withdrawal symptoms if they try. This can include feeling tired and anxious and suffering headaches.

“I don’t know if I could do without coffee. That first cup in the morning gets me up. Off to work and the first thing is coffee. Basically I drink at least 8 cups a day and the stronger the better. If you said to me don’t drink coffee tomorrow I would get very anxious about trying to do it. I don’t think I would last very long without it.”

Research into the health effects of long term use of caffeine is inconclusive. However, some reports have suggested that it can lead to a higher incidence of asthma, peptic ulcers, kidney, bladder and heart disease and blood pressure problems.

“We have seen several well-marked cases of coffee excess…. The sufferer is tremulous, and looses his self-command; he is subject to fits of agitation and depression; he looses colour and has a haggard appearance. The appetite falls off, and symptoms of gastric catarrh may be manifested. The heart also suffers; it palpitates, or it intermits. As with other such agents, a renewed dose of the poison gives temporary relief, but at the cost of future misery’.

Sir T.C. Allbutt and H.D. Rolleston A system of medicine 1909.

There have also been concerns about the amount of caffeine consumed by young children particularly in soft drinks and chocolate. Some commentators have suggested that children who consume a lot of caffeine may become hyperactive. A child drinking one can of cola will be taking the equivalent caffeine intake as an adult drinking four cups of coffee.

DrugWatch Information Sheet: Caffeine & Energy Drinks

Last updated April 2022

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