Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.
Separate acute severe blood pressure without organ injury from accelerated hypertension and true emergency, investigate target-organ damage and lower pressure at the right speed.
Severe BP may be cause, consequence or bystander. Pain, anxiety, hypoxia, urinary retention, cocaine/amphetamines, medication withdrawal and raised intracranial pressure can elevate BP; treat these while actively seeking organ injury.
The emergency assessment is syndrome-led: encephalopathy/seizure, stroke, ACS, pulmonary oedema, aortic dissection, AKI/haematuria, microangiopathic haemolysis and pregnancy-related disease each change drug choice and target.
Autoregulation shifts in chronic hypertension. Dropping pressure too far or too fast can reduce organ perfusion, which is why monitored titration and repeated neurological, cardiac and renal assessment matter more than achieving a normal cuff value.
Long-standing poorly controlled hypertension, missed treatment or medication withdrawal can permit a marked pressure rise. Chronic vascular injury also makes the brain, kidneys, retina and heart vulnerable when control deteriorates.
Pain, anxiety, hypoxia, urinary retention and cocaine or amphetamine exposure can acutely increase sympathetic tone. These may precipitate severe hypertension or simply accompany another emergency, so organ injury must still be sought.
Acute renal dysfunction may both raise pressure and result from it. Labile hypertension with headache, palpitations, pallor or sweating suggests a catecholamine-secreting tumour and requires specialist assessment.
Pre-eclampsia and eclampsia can produce severe hypertension with neurological, hepatic, renal or placental injury. Pregnancy changes both the relevant treatment pathway and the medicines considered safe.
A marked rise in arterial pressure increases wall stress throughout the circulation. When vascular protective mechanisms are exceeded, endothelial injury and small-vessel dysfunction begin to impair target-organ perfusion.
Cerebral autoregulation can fail at very high pressure, allowing hyperperfusion, vasogenic oedema and encephalopathy. Headache, confusion, visual disturbance or seizures may follow; fundoscopy may show retinal haemorrhages and/or papilloedema.
Damaged arterioles narrow or leak, producing renal injury, haematuria and proteinuria. Red cells and platelets may be mechanically disrupted in the microcirculation, causing thrombocytopenia and fragmented cells.
Increased afterload raises myocardial oxygen demand and can increase left-ventricular filling pressure, contributing to ischaemia or pulmonary oedema. Aortic wall stress may precipitate or extend an acute aortic syndrome in susceptible people.
Chronic hypertension shifts organ autoregulation towards higher pressures. An uncontrolled rapid fall can therefore reduce cerebral, coronary or renal blood flow even though the measured pressure remains above the usual range.
BP at least 180/120 mmHg plus retinal haemorrhage and/or papilloedema; often accompanied by headache, visual symptoms, renal injury or microangiopathy.
New confusion, agitation, headache, visual disturbance, nausea/vomiting or seizures with severe hypertension after excluding stroke and other causes.
Chest/back pain, pulse deficit, acute pulmonary oedema, myocardial ischaemia or new aortic regurgitation requires immediate syndrome-specific care.
Oliguria, rising creatinine, haematuria/proteinuria, thrombocytopenia or fragmented red cells supports acute organ damage.
Repeated BP at least 180/120 but no retinal or life-threatening features; needs prompt investigation and 7-day confirmation/review rather than routine IV reduction.
Labile/postural hypertension with headache, palpitations, pallor, diaphoresis or abdominal pain merits same-day specialist assessment under NICE.
Repeated severe readings can occur without acute target-organ injury. Accurate measurement after rest, no retinal or life-threatening features, and no acute renal, cardiac or neurological injury favour prompt outpatient confirmation and review rather than routine intravenous reduction, provided the person remains clinically stable.
A focal neurological deficit or abrupt severe headache favours a structural cerebrovascular event over diffuse hypertensive encephalopathy. Brain imaging is needed because hypertension may be a consequence as well as a cause.
Abrupt chest, back or abdominal pain maximal at onset, a pulse or pressure difference, new aortic regurgitation or malperfusion raises concern for an acute aortic syndrome. This requires immediate aortic-team assessment and appropriate imaging; haemodynamic treatment should follow the aortic protocol and preserve organ perfusion.
Stimulant exposure or episodic headache, palpitations, pallor and sweating suggests a sympathetic cause. The history may be labile or paroxysmal, but acute organ injury still determines emergency status.
Severe pain, agitation, urinary retention or raised intracranial pressure can drive a reactive pressure rise. Treating the precipitant and observing the trend helps, while syndrome-specific tests assess for concurrent target-organ injury.
Loss of cerebral autoregulation causes oedema, headache, confusion, visual disturbance and seizures. Without controlled treatment, neurological injury may progress and airway protection can become necessary.
Small-vessel rupture or vascular occlusion can produce intracerebral haemorrhage or ischaemic stroke. These syndromes require their own pressure targets because excessive reduction may worsen threatened brain perfusion.
Afterload and oxygen-demand mismatch may cause myocardial ischaemia, while rising filling pressure can produce acute heart failure and pulmonary oedema. In a patient with severe hypertension, either represents clinically important acute target-organ injury, although the cardiac cause still needs syndrome-specific assessment.
Renal arteriolar injury reduces filtration and can cause oliguria, rising creatinine, haematuria and proteinuria. Kidney dysfunction also complicates fluid management and selection of antihypertensive treatment.
Severe small-vessel damage can fragment red cells and consume platelets, producing haemolytic anaemia and thrombocytopenia. This pattern signals extensive vascular injury and higher-acuity management.
The term is not synonymous with any BP above 180/120; retinal haemorrhage and/or papilloedema is the defining NICE feature.
Severe BP without organ injury still needs prompt target-organ testing and a 7-day confirmation/review plan.
Aortic dissection and stroke require different rates and destinations even at the same starting BP.
Analgesia and relief of urinary retention, hypoxia or withdrawal can reduce BP and prevent unnecessary drug escalation.
Sublingual/immediate-release nifedipine can cause abrupt hypotension and organ ischaemia; monitored titration is safer.
Calling every BP above 180/120 a hypertensive emergency without looking for acute organ injury.
Discharging severe asymptomatic hypertension without target-organ tests and a 7-day review plan.
Trying to normalise chronic severe BP within minutes in a generic emergency.
Giving vasodilator before heart-rate/impulse control in suspected aortic dissection.
Missing papilloedema because fundoscopy was omitted.
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A patient has BP 204/128 mmHg and bilateral retinal haemorrhages. They have no chest pain. What is the correct disposition?
National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.
Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes
Avoid with asthma/bronchospasm, marked bradycardia, heart block or decompensated systolic failure; monitor supine because postural hypotension can persist. Syndrome-specific dosing may differ.
Continuous monitoring required; may cause tachycardia, headache or hypotension. In acute aortic syndrome, control heart rate/impulse first to avoid reflex shear stress.