Caffeine – a summary

by 22 Jul 2008

Caffeine is a drug of choice for the majority of people in modern society. A CNS (central nervous system) stimulant, it is used by many to enhance mental alertness and drive away feelings of fatigue. But is this safe?

Effects: Upon ingestion, the effect of caffeine lasts for about six hours and includes increased mental alertness. Other less-known effects – anxiety, dizziness, headache, jitters, sleep disturbance, hypertension, palpitations and muscle twitching – can all occur with moderate prolonged intake of caffeine. Excessive intake (more than 4 cups of coffee per day) can cause an increase in miscarriage risk. Even more serious long-term effects can occur, including peptic ulcer disease and osteoporosis. While sensitivity varies, decreasing with increasing dose, over time most heavy consumers of caffeine will develop some or all of these side effects, even though some may be masked by tolerance.

Where is it found? In coffee, tea, cola, soft drinks, energy drinks and chocolate.

What is the safe level? As a rough guide, consumption of 200-300mg/day (two to three cups of brewed coffee or three to four cups of tea) is thought to be a reasonable intake for adults. Teenagers and pregnant women should consume no more than 100mg/day.

Can I be addicted? Consumption of more than 10mg/day can lead to dependence. Upon cessation of caffeine consumption, withdrawal symptoms including tiredness, irritability and headache can develop. Importantly, this may be followed by an improvement in concentration and mental clarity.

Is decaffeinated OK? There are various methods of decaffeinating coffee and tea. A water and charcoal-based method is not only safer but also produces a truer-tasting product. Decaffeinated products still contain limited amounts of caffeine.

By Dr Jo-Anne Zappia, director of medical services, Peak Health Management. Email or visit