Many people ingest caffeine on a daily basis, whether through coffee, tea or soft drinks. Energy drinks, chocolate and some medications may also be sources of caffeine. While this habit may not create any problems for most people, caffeine can have an impact on your blood pressure.
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Coffee and Blood Pressure
According to a study in the October 2011 issue of the "American Journal of Clinical Nutrition," drinking coffee substantially raises your blood pressure for up to three hours after consumption. Researchers state that 200 to 300 milligrams of caffeine, equal to 2 to 3 cups of coffee depending on the strength, raised the systolic number by 8.1 millimeters of mercury and the diastolic by 5.7. This change took place within an hour of consumption. While researchers observed an immediate increase in blood pressure, they say that being a coffee drinker does not necessarily raise your blood pressure in the long term.
Caffeine and Hypertension
A research team led by Terry R. Hartley reported in the January 2000 issue of "Hypertension" that if you have a risk of hypertension, caffeine causes increasingly large blood pressure responses. They found that men who already had a diagnosis of hypertension had a pre-to-postdrug change in BP that was more than 1.5 times greater than the group with optimal blood pressure. Men with normal blood pressures did not show the caffeine effect, but men who had prehypertension did react to caffeine. In other words, a high normal blood pressure may increase enough after ingesting caffeine to put you in the hypertension range.
In an older study reported in the 1999 issue of "Hypertension", Valentina Rakic, Valerie Burke and Lawrence J. Beilin noted that patients with hypertension had increases in ambulatory blood pressure after caffeine, even when they were on medication for hypertension. Caffeine can also interact with medications, including medications for high blood pressure. Caffeine may interact with the beta-blockers propranolol and metoprolol, both of which are used to treat high blood pressure. The interaction makes the medications less effective and results in a higher overall blood pressure.
Considerations and Warnings
If you think caffeine might be affecting your blood pressure, take a blood pressure reading within 30 minutes of ingesting your normal source of caffeine. A rise of 5 to 10 points could mean you are caffeine sensitive. Do not make changes in your medication as a result of this home test. If you are already on medication or have concerns or questions, be sure to talk to a health care professional about whether caffeine is a potential problem for you.
Is This an Emergency?
- American Journal of Clinical Nutrition: The Effect of Coffee on Blood Pressure and Cardiovascular Disease on Hypertensive Individuals
- Hypertension: Hypertension Risk Status and Effect of Caffeine on Blood Pressure
- Hypertension: Effects of Coffee on Ambulatory Blood Pressure in Older Men and Women: A Randomized Controlled Trial
- University of Maryland Medical Center: Possible Interactions With: Green Tea