However, studies have observed mixed results, and some people may experience negative side effects at intakes of less than 400 mg per day ( 2, 4). One review study showed that 300 mg of caffeine per day in healthy pregnant women is safe, with limited data suggesting that 1.1 mg of caffeine per pound (2.5 mg per kg) of body weight in children and adolescents may be safe ( 2).
Consuming up to 400 mg of caffeine per day has not been associated with adverse health effects in healthy adults ( 1, 2, 3). The Food and Drug Administration (FDA) generally recognizes caffeine as safe. The term “psychostimulant” means that it increases the activity of the nervous system ( 1, 3).
Caffeine is the most commonly consumed psychostimulant substance in the world.
