Caffeinated drinks (generally low risks of harm).
Caffeine is found in drinks like coffee, tea, and mate (a tea drunk in Argentina). Caffeine can also be found in ‘energy drinks’ which have high caffeine content, and some soft drinks. In Europe, drinks (not based on coffee or tea) with a caffeine content of more than 150 mg per litre, have to be labelled as high caffeine content with the amount of caffeine on it.
Shops also sell caffeine shots, which are small amounts of sugary drink with a high caffeine content. Like alcohol shots, it is easy to drink a lot of these quickly before realising you have had too much.
It is common to become addicted to caffeinated drinks, in that stopping use will lead to withdrawal symptoms, although most people would not find it difficult to stop caffeine use.
Caffeine is often listed as a flavouring on soft drinks, although it may not be the case that caffeine adds to the taste of the drink, rather it increases the desire to consume it.
Caffeine tablets (low risk if used according to directions, potential for overdose if misused)
Caffeine tablets are legal and are used to increase alertness. Some beliefs about their effectiveness, for example in improving exam performance, are not wholly supported by the evidence. They do not replace the need for sleep, in fact a nap can be much more beneficial.
Caffeine as an adulterant in illegal drugs (could sometimes be harmful)
Analysis of drug samples show that caffeine is commonly added, which adds bulk cheaply and so increases the dealers’ profits. Caffeine has been identified in heroin, where it may make the drug easier to smoke. It is commonly added to stimulant drugs like cocaine, amphetamine (speed) and MDMA (ecstasy) where its stimulant effects may disguise how impure the drug is, and may also increase the risks.