Caffeine is thought to possibly block a hormone that helps to keep the arteries widened, or possibly cause the adrenal glands to release more adrenaline which causes blood pressure to increase.
Those who drink caffeinated beverages regularly tend to have higher average blood pressure that those who don’t, and some who drink them on a regular basis can also develop a tolerance to caffeine and as a result, caffeine doesn’t have a long term effect on their blood pressure.
For those that do have high blood pressure it is recommended to consult with your doctor to determine whether you should limit or stop drinking caffeinated beverages altogether. If you are concerned about the effect on blood pressure try to limit the amount of caffeine to 200 mg a day, which is about the amount in two cups of coffee, but this amount may vary by brand and method of preparation.
It may also be best to avoid caffeine just before participating in any activity that will naturally increase blood pressure such as exercise, weightlifting or hard physical labor if you have high blood pressure.
It is relatively easy to check if caffeine may be increasing your blood pressure: check your blood pressure before drinking a caffeinated beverage, then again about 30-120 minutes after drinking the beverage; you may be sensitive to the blood pressure increasing effect of caffeine if your blood pressure increases by 5-10 points after drinking a caffeinated beverage.
If you are planning to reduce your caffeine intake, the best approach may be to gradually cut back your intake spread out over several days to a week to help avoid experiencing undesirable withdrawal headaches.
