[5] The treatment of moderately high arterial blood pressure (defined as >160/100 mmHg) with medications is associated with an improved life expectancy.

Some people with high blood pressure report headaches, as well as lightheadedness, vertigo, tinnitus (buzzing or hissing in the ears), altered vision or fainting episodes.

Coarctation of the aorta frequently causes a decreased blood pressure in the lower extremities relative to the arms, or delayed or absent femoral arterial pulses.

[29] In a hypertensive emergency, the blood pressure must be reduced more rapidly to stop ongoing organ damage;[29] however, there is a lack of randomized controlled trial evidence for this approach.

[35][36] Pre-eclampsia is a serious condition in the second half of pregnancy and following delivery characterised by increased blood pressure and the presence of protein in the urine.

Pre-eclampsia can occasionally progress to a life-threatening condition called eclampsia, which is a hypertensive emergency and has several serious complications including vision loss, brain swelling, seizures, kidney failure, pulmonary edema, and disseminated intravascular coagulation (a blood clotting disorder).

In older infants and children, hypertension can cause headache, unexplained irritability, fatigue, failure to thrive, blurred vision, nosebleeds, and facial paralysis.

[44] There is also evidence that DNA methylation at multiple nearby CpG sites may link some sequence variation to blood pressure, possibly via effects on vascular or renal function.

[53] Increasing alcohol intake is associated with higher blood pressure,[54] but the possible roles of other factors such as caffeine consumption,[55] and vitamin D deficiency[56] are less clear.

Gout and elevated blood uric acid are associated with hypertension[63] and evidence from genetic (Mendelian Randomization) studies and clinical trials indicate this relationship is likely to be causal.

[72] These individuals may develop the typical features of established essential hypertension in later life as their cardiac output falls and peripheral resistance rises with age.

[73] The increased peripheral resistance in established hypertension is mainly attributable to structural narrowing of small arteries and arterioles,[74] although a reduction in the number or density of capillaries may also contribute.

In the United Kingdom, the current best practice is to follow up a single raised clinic reading with ambulatory measurement, or less ideally with home blood pressure monitoring over 7 days.

[42] Hypertension defined as elevated blood pressure over several visits affects 1% to 5% of children and adolescents and is associated with long-term risks of ill-health.

[101] There is considerable evidence that reducing dietary salt intake lowers blood pressure, but whether this translates into a reduction in mortality and cardiovascular disease remains uncertain.

[103] Consequently, in the absence of results from randomized controlled trials, the wisdom of reducing levels of dietary sodium intake below 3 g/day has been questioned.

[108] However, the American Academy of Family Physicians[109] supports the view of the U.S. Preventive Services Task Force that the available evidence is insufficient to determine the balance of benefits and harms of screening for hypertension in children and adolescents who do not have symptoms.

[110][111] The US Preventive Services Task Force recommends screening adults 18 years or older for hypertension with office blood pressure measurement.

Though these have all been recommended in scientific advisories,[125] a Cochrane systematic review found no evidence (due to lack of data) for effects of weight loss diets on death, long-term complications or adverse events in persons with hypertension.

[138] Stress reduction techniques such as biofeedback or transcendental meditation may be considered as an add-on to other treatments to reduce hypertension, but do not have evidence for preventing cardiovascular disease on their own.

[147] Resistant hypertension is defined as high blood pressure that remains above a target level, despite being prescribed three or more antihypertensive drugs simultaneously with different mechanisms of action.

[153] Refractory hypertension is described by one source as elevated blood pressure unmitigated by five or more concurrent antihypertensive agents of different classes.

[154] People with refractory hypertension typically have increased sympathetic nervous system activity, and are at high risk for more severe cardiovascular diseases and all-cause mortality.

[30] Modern understanding of the cardiovascular system began with the work of physician William Harvey (1578–1657), who described the circulation of blood in his book "De motu cordis".

[174] The symptoms include headache, heaviness in the head, sluggish movements, general redness and warm to touch feel of the body, prominent, distended and tense vessels, a fullness of the pulse, distension of the skin, coloured and dense urine, loss of appetite, weak eyesight, impairment of thinking, yawning, drowsiness, vascular rupture, and hemorrhagic stroke.

[178] Historically the treatment for what was called the "hard pulse disease" consisted of reducing the quantity of blood by bloodletting or the application of leeches.

In the 19th and 20th centuries, before effective pharmacological treatment for hypertension became possible, three treatment modalities were used, all with numerous side effects: strict sodium restriction (for example the rice diet[171]), sympathectomy (surgical ablation of parts of the sympathetic nervous system), and pyrogen therapy (injection of substances that caused a fever, indirectly reducing blood pressure).

[171] Several other agents were developed after the Second World War, the most popular and reasonably effective of which were tetramethylammonium chloride, hexamethonium, hydralazine, and reserpine (derived from the medicinal plant Rauvolfia serpentina).

[184] High blood pressure is the most common chronic medical problem prompting visits to primary health care providers in the US.

[189] Inhibitors of the renin-angiotensin system and calcium channel blockers are often used to treat hypertension in dogs, although other drugs may be indicated for specific conditions causing high blood pressure.