Common Effects of Caffeine

7. Fast Pulse and Elevated Blood Pressure

As caffeine stimulates the body, it also increases the resting and active heart rates. A fast pulse or fluttery feeling is a common effect of too much caffeine. Excess caffeine can also alter the rhythm of the heart, a condition known as atrial fibrillation. High-caffeine energy drinks are a common cause, especially when those drinking them don't typically consume much caffeine. However, those who lift heavy swear by the added boost; these "pre-workout" drinks and supplements can give them the energy and extra blood flow necessary for lifting heavy weights.

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