Caffeine is an extremely popular psychoactive substance and central nervous system stimulant. Most commonly consumed in coffee, it is generally considered safe if consumed if moderate amounts.
The Mayo Clinic has concluded that, in general, adults can safely consume up to 400 milligrams (mg) of caffeine a day, approximately the amount in four cups of coffee or ten cans of cola.
Caffeine increases your metabolic rate and therefore many whom consume it experience increased alertness, blood pressure, breathing rate and alertness. Caffeine is also a diuretic, meaning it can lead to increased urination, and even dehydration.
However, over time, caffeine usage can lead to insomnia, nervousness and stomach irritation in some and should therefore not be used in large amounts over long periods of time. If someone is experiencing these effects and suspects they are tied to caffeine, they should moderate it’s usage and discuss the issue with their doctor or other healthcare professional.
Caffeine is also considered to have a therapeutic impact on pain, having both anti-inflammatory and antioxidant properties, according to Kamil Rodak et al writing in the journal Nutrients.
Additional studies on caffeine are ongoing and should shed additional light on both its positive and negative effects.