title: Timing of blood pressure measurement related to caffeine consumption.
abstract: OBJECTIVE
  To determine whether patients should wait 30 minutes after caffeine consumption to have their blood pressure measured.
  
  
  METHODS
  Literature was obtained by searching MEDLINE (1980-September 2007), International Pharmaceutical Abstracts (1980-September 2007), and the Cochrane Database of Systematic Reviews (1994-September 2007). Search terms included caffeine and blood pressure. Literature was also obtained from citations in relevant articles.
  
  
  METHODS
  Articles that examined caffeine's acute effect on blood pressure were reviewed, with additional focus on caffeine tolerance and hypertensive status.
  
  
  RESULTS
  Caffeine appears to affect blood pressure through adenosine receptor inhibition and an increased release of select neurotransmitters. Caffeine levels peak 30-120 minutes after oral intake and caffeine's half-life is 3-6 hours. The effect of caffeine on blood pressure has been examined for decades, with variable results depending on factors such as population examined (eg, hypertensive status, physical stressors, age) and study design (eg, acute effects, chronic ingestion, retrospective epidemiologic review). Caffeine tolerance diminishes the acute effect of caffeine on blood pressure, and hypertensive individuals are more susceptible to blood pressure changes. Reviews of caffeine's acute effect on blood pressure indicate changes of 3-15 mm Hg systolic and 4-13 mm Hg diastolic. Typically, blood pressure changes occur within 30 minutes, peak in 1-2 hours, and may persist for more than 4 hours.
  
  
  CONCLUSIONS
  Having a patient abstain from caffeine for 30 minutes prior to blood pressure monitoring is not adequate to avoid caffeine's potential effects. An alternative approach to blood pressure monitoring would be to ask the patient about recent caffeine consumption and interpret the blood pressure reading based on this information. In addition, healthcare practitioners should provide education regarding caffeine's effects.
authors: College of Pharmacy, South Dakota State University, Sioux Falls, SD 57107, USA. jane.mort@sdstate.edu
authors: Jane R
authors: JR
authors: Mort
authors: Heather R
authors: HR
authors: Kruse
mesh_terms: D001794:Blood Pressure / Q000187:drug effects*; D002110:Caffeine / Q000493:pharmacokinetics / Q000494:pharmacology*; D000697:Central Nervous System Stimulants / Q000493:pharmacokinetics / Q000494:pharmacology*; D006801:Humans; D006973:Hypertension / Q000175:diagnosis / Q000503:physiopathology; D018377:Neurotransmitter Agents / Q000378:metabolism; D010353:Patient Education as Topic; D018047:Receptors, Purinergic P1 / Q000187:drug effects / Q000378:metabolism; D013997:Time Factors
chemical_list: D000697:Central Nervous System Stimulants; D018377:Neurotransmitter Agents; D018047:Receptors, Purinergic P1; D002110:Caffeine