High blood pressure does not cause headaches, except possibly when a hypertensive crisis has occurred. This is defined by a blood pressure with a systolic (top) reading of at least 180 and/or a diastolic (bottom) reading of at least 110, as stated by American Heart Association.
In the early twentieth century, the common assumption was that people suffering from high blood pressure had headaches more frequently. However, scientific research into the connection did not support that assumption. In fact, one study found that people who have high blood pressure have headaches much less often than the population at large, notes the American Heart Association.
The journal "Neurology" published a study finding that people with higher systolic blood pressure were as much as 40 percent less likely to suffer from headaches than people with systolic readings in a healthier range. The study also analyzed the effect of pulse pressure, which is the alteration in blood pressure at heart contraction. Subtracting the diastolic reading from the systolic reading yields the pulse pressure, and those with higher pulse pressures had up to 50 percent fewer instances of headache. The researchers suggested that a higher pulse pressure yields stiffer blood vessels, which cause dysfunction in the nerve endings. Faulty nerve endings make it less likely that a person is going to notice pain, according to the American Heart Association.