Hypertension is often referred to as the "silent killer" because it usually has no hallmark or general symptoms. The American Heart Association (AHA) mentions that if you try to find a series of symptoms or signs of high blood pressure, you may find nothing because there is no such “symptom” at all. But in turn, high blood pressure sometimes may present some symptoms, such as headaches.
The relationship between headaches and hypertension has been debated for years and still remains controversial. There are even studies that have conflicting conclusions. Today, let’s take a closer look at the association between headaches and hypertension.
Are headaches related to elevated blood pressure?
Studies indicated that there is a positive relationship between headaches and blood pressure, that is, headaches are related to increased blood pressure. A study published in 2016 included 1914 people with hypertension and divided them into three subgroups: migraine, daily headache, and other headaches. The analysis found that all headache types were positively correlated with diastolic blood pressure (DBP) (see Table 1) 【1】. Consistent with this result, randomized controlled trials have shown that the use of beta blockers, thiazide diuretics, angiotensin receptor blockers, and angiotensin-converting enzyme inhibitors can reduce headache frequency 【1】. An article published by Hansson et al. in 2000 indicated that mild hypertension is not asymptomatic, and the incidence of headaches can be reduced by antihypertensive treatment 【2】.
High blood pressure but lower likelihood of headaches?
On the one hand, research results show a positive relationship between headaches and blood pressure, while on the other hand, there are studies that come to very different conclusions. A study of 22,685 adults in Norway found that high systolic and diastolic blood pressure was associated with a lower risk of non-migraine headaches. The study measured baseline blood pressure in the group of adults who were less prone to headaches in 1984-86, and collected a headache questionnaire at follow up 11 years later (1995-97) to assess the relative risk of headaches Relationship with baseline blood pressure 【3】. The analysis found that patients with systolic blood pressure greater than or equal to 150 mm Hg had a 30% lower risk of developing non-migraine headaches compared to patients with systolic blood pressure less than 140 mm Hg. For diastolic blood pressure, the risk of non-migraine headache decreased with increasing values, and these findings were similar in both sexes and were not affected by the use of antihypertensive medication.
A possible biological explanation for this inverse relationship between systolic blood pressure and headaches is called "hypalgesia" associated with hypertension. Its mechanism is unclear, but data from humans and mice suggest that the baroreflex system may regulate pain perception, possibly involving endorphinergic and noradrenergic neurons in the brainstem and spinal cord. Of particular relevance to the study's findings is that the inverse relationship between blood pressure levels and sensitivity to painful stimuli extends to the normotensive range.
Research does find that some hypertensive patients may experience more frequent and severe headaches 【4】. In one extreme case, increased blood pressure can cause headaches, known as “hypertensive crisis”. Hypertensive crisis is an acute and severe increase in blood pressure, described as systolic blood pressure (SBP) >180 mmHg, or diastolic blood pressure (DBP) >120 mmHg 【4】. It usually occurs in patients with a history of hypertension and is a severe uncontrolled episode. When a hypertensive crisis occurs, there are many symptoms. Headache is one of these symptoms. Other symptoms include neurological problems and chest pain. The patient must go to the hospital urgently. If there is evidence of damage to organs such as the heart, brain or kidney, the patient is admitted to the intensive care unit (ICU). Enough attention must be paid to it.
In conclusion, the relationship between headaches and blood pressure is not simple. Headaches and hypertension are common in the general population and inevitably coexist. There is no absolute relationship between them. However, if you are being treated for hypertension and your headaches are frequent or getting worse, you will need to seek for medical supports immediately.
【1】Courand PY, Serraille M, Girerd N, Demarquay G, Milon H, Lantelme P, Harbaoui B. The paradoxical significance of headache in hypertension. Am J Hypertens. 2016 Sep;29(9):1109-16. doi:10.1093/ajh/hpw041
【2】 Hansson L, Smith DH, Reeves R, Lapuerta P. Headache in mild-to moderate hypertension and its reduction by irbesartan therapy. Arch Intern Med 2000; 160:1654–1658.
【3】Hagen K, Stovner LJ, Vatten L, Holmen J, Zwart JA, Bovim G. Blood pressure and risk of headache: a prospective study of 22 685 adults in Norway. J Neurol Neurosurg Psychiatry. 2002 Apr;72(4):463-6. doi:10.1136/jnnp.72.4.463
【4】Assarzadegan F, Asadollahi M, Hesami O, Aryani O, Mansouri B, Beladi moghadam N. Secondary headaches attributed to arterial hypertension. Iran J Neurol. 2013;12(3):106-10.