Fast Five Quiz: Caffeine Clinical Concerns

Mary L. Windle, PharmD


February 12, 2021

In humans, tolerance to some physiologic actions of caffeine can occur. This is the case for the effects of caffeine on blood pressure, heart rate, diuresis, plasma adrenaline and noradrenaline levels, and renin activity. Tolerance usually develops within a few days. However, overnight abstinence is often sufficient to negate the tolerance effects to most levels of caffeine ingestion in typical caffeine users.

Although tolerance to the enhancement of arithmetic skills by caffeine has been documented, evidence of tolerance to caffeine-induced alertness and wakefulness is limited. These effects are paralleled by the lack of tolerance of cerebral energy metabolism to caffeine.

Caffeine withdrawal results in typical symptoms, the most commonly reported of which are:

  • Headaches

  • Fatigue

  • Weakness

  • Drowsiness

  • Impaired concentration

  • Work difficulty

  • Depression

  • Anxiety

  • Irritability

  • Increased muscle tension

  • Tremor, nausea, and vomiting (occasionally)

The symptoms of caffeine withdrawal typically begin 12-24 hours after cessation, peaking at 20-51 hours, and last 2-9 days. Withdrawal symptoms do not relate to the quantity of caffeine ingested daily.

Read more about the neurologic effects of caffeine.


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