High blood pressure does not necessarily cause headaches.

except perhaps in the case of hypertensive crisis (blood pressure > 180/110 mmHg).

People with high blood pressure seem to have significantly fewer headaches than the general population.

The higher the pulse pressure, the stiffer the blood vessels. In the stiffer blood vessel, there is less chance of nerve endings working properly.

If the nerve endings aren’t functioning correctly, there is less chance that person might feel pain.

In other words, headache is not a reliable symptom of hypertension.