title: The effect of caffeine on daytime ambulatory blood pressure.
abstract: Caffeine produces an acute increase in blood pressure in the research laboratory, but its effect on the ambulatory blood pressure during normal daily activities is unknown. In 25 normotensive, caffeine-naive subjects, daily administration of 400 mg caffeine produced a small increase (+3/+3 mm Hg, P less than .001) in ambulatory daytime blood pressure on the first day, with values returning to baseline by the third day. The initial rise in blood pressure was associated with a fall in heart rate (-3 beats/min, P less than .02). Readings taken the morning following the first day of caffeine ingestion did not show any persistent effect of caffeine on blood pressure. A 400 mg dose of caffeine causes a small increase in daytime ambulatory blood pressure, but tolerance develops with daily caffeine consumption. Infrequent ingestion of caffeine may cause a transient rise in blood pressure which is unlikely to be harmful to an individual but might influence the diagnosis of hypertension in a patient with a borderline elevated blood pressure.
authors.affiliation: Division of Cardiology, Sunnybrook Health Science Centre, Toronto, ON, Canada.
authors.forename: M G
authors.initials: MG
authors.lastname: Myers
authors.forename: R A
authors.initials: RA
authors.lastname: Reeves
mesh_terms: D000328:Adult; D000553:Ambulatory Care; D001794:Blood Pressure; D001795:Blood Pressure Determination / Q000379:methods*; D002110:Caffeine / Q000097:blood / Q000494:pharmacology*; D002940:Circadian Rhythm; D005260:Female; D006801:Humans; D008297:Male; D009994:Osmolar Concentration; D012016:Reference Values; D013997:Time Factors
chemical_list: D002110:Caffeine