Dose and Toxicity
Caffeine at high doses (> 400 mg daily) and in susceptible patients can induce anxiety, but the effects of caffeine on sleep and anxiety can differ from patient to patient. This variation reflects differences in caffeine metabolism rate and adenosine receptor gene variants.
High caffeine intake can stimulate diuresis, but without causing damaging effects on hydration when taking moderate doses of caffeine (≤ 400 mg daily) for long periods. Stopping caffeine suddenly, in a regular consumer, can lead to withdrawal symptoms such as headache, asthenia, decreased attention, depressed mood, and flu-like symptoms.
The toxic effects of caffeine occur with intake > 1.2 g. A dose of 10-14 g is considered fatal. Caffeine overdose is rare when considering traditional methods of intake (coffee and tea) because 70-100 cups of coffee should be sufficient for caffeine poisoning. Severe events can occur following the use of caffeine tablets or as energy drinks for the following reasons:
- The episodic consumption of caffeine does not allow for tolerance to develop.
- Young people are more vulnerable to the effects of caffeine.
- Caffeine has a synergistic effect in combination with other components in energy drinks.
- Taking caffeine in combination with alcohol or intense exertion causes serious, even fatal, outcomes.
Products Containing Caffeine
Evidence supports the relationship between high consumption (approximately 1 L) of energy drinks with a caffeine content of 320 mg and short-term cardiovascular adverse events, such as increased BP, QT-segment prolongation corrected for heart rate, and palpitations. These tests prompt the recommendation to avoid consuming these beverages in high quantities and in association with alcohol.
Weight loss products generally contain caffeine coupled with herbal extracts that are expected to improve fat metabolism, lipolysis, and oxidation. These products, because of their easy availability, presumed benefits, and high caffeine concentration, may be more susceptible to misuse because they can be taken in larger portions than recommended. The combination of multiple ingredients, concentrated amounts of caffeine, and excessive consumption increases the likelihood of adverse effects.
This story was translated from Univadis Italy, which is part of the Medscape professional network, using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication. A version of this article appeared on Medscape.com.