Somehow, it just seems to make sense that high blood pressure would cause headaches. Maybe it's the word "pressure," which is what a headache often feels like. Possibly it is the sense that the blood is agitated and pounding against the inside of the skull.
Research into the "high blood pressure headache" phenomenon began as early as 1913, when physician Theodore Janeway identified "morning headaches" as a common symptom of high blood pressure. These headaches, he noted, seemed to decrease in severity as the day wore on. Janeway was a man of considerable credibility, one of the first professors of medicine at John's Hopkins University. Yet that didn't necessarily make him right. Recent research seems to indicate that there is actually no causal link between high blood pressure and a high blood pressure headache.
A Polish study for the Journal of Human Hypertension, for example, hooked 150 high blood pressure patients up with portable monitors that worked continuously. At the end of the study, 43 reported having headaches — but when those instances were compared with the blood pressure readings at the time, there seemed to be no correlation.
Far more extensive was a month-long high blood pressure headache survey conducted by the Journal of Neurology, Neurosurgery and Psychiatry, which extended to 22,000 adults and also found no connection.
The one frightening exception, apparently, is a condition called "malignant hypertension," in which extremely high blood pressure swells the optic nerve behind the eye and can cause a blinding headache. This occurs in only 1 percent of people with high blood pressure, with young African-American males most at risk.
As for the other 99 percent, yet another study (from Norway) found those with high blood pressure may actually have fewer headaches than a control group. That's because beta-blockers, a popular family of drugs for lowering blood pressure, is also a primary clinical weapon against migraine headaches.
Part of the supposed headache/high blood pressure link could be also be coincidental. People with severe headaches are more likely to visit a doctor or hospital, where their blood pressure is taken. There is even speculation that the anxiety of being diagnosed with high blood pressure could cause a "high blood pressure headache." Some of the same diet and lifestyle factors can cause both.
Nevertheless, Malcolm Law isn't completely convinced. A professor of epidemology at the University of London, he told WebMD: "My best guess is that high blood pressure does cause headaches — but that's just a guess."
The preponderance of evidence, though, suggests strongly that having a headache if you're prone to high blood pressure is nothing to worry about. A couple of aspirins often put the matter to rest.