Drinking caffeinated beverages can temporarily cause a spike in your blood pressure. If you have reason to be worried about caffeine's effect on your blood pressure, try limiting the amount of caffeine you drink to 200 milligrams a day — about the same amount as in two 12-ounce (355-milliliter) cups of brewed coffee. Also, avoid caffeine right before activities that naturally increase your blood pressure, such as exercise or hard physical labor.