01 - Caffeine

Caffeine

The Maudsley® Prescribing Guidelines in Psychiatry, Fifteenth Edition. David M. Taylor, Thomas R. E. Barnes and Allan H. Young. © 2025 David M. Taylor. Published 2025 by John Wiley & Sons Ltd. Chapter 12 Caffeine Caffeine is probably the most used psychoactive substance in the world. Mean daily consumption in the UK is 350–620mg.1 A quarter of the general population and half of  those with psychiatric illness regularly consume over 500mg caffeine per day.2 Consumption of caffeine should be routinely discussed with an individual to assess its effect on their symptoms and presentation.3 Both caffeine intake and caffeine withdrawal can have a marked effect on mental and physical health. Most caffeine intake is in the form of coffee and tea but increasingly in the form of energy drinks (Table 12.1). Caffeine is also a constituent of chocolate and hundreds of over-­the-­counter medicines where it is often included as a co-­analgesic. Other substances Table 12.1  Typical caffeine content of drinks. Drink Caffeine content Brewed coffee4 100mg/cup (around 100mg per espresso shot) Red Bull 80mg/can (other energy drinks may contain substantially more; volume of cans varies substantially) Instant coffee 60mg/cup Black tea 45mg/cup Soft drinks (sodas) 25–50mg/can Green tea 20–30mg/cup Decaffeinated coffee 3–16mg5