Combined alpha and beta blocker Pregnancy: Not expected to increase the risk of congenital malformations based on human pregnancy experience; animal studies do not indicate teratogenicity but embryo-foetal developmental toxicity has been noted. Labetalol crosses the placenta — bradycardia, hypotension, respiratory depression and hypoglycaemia may occur in the foetus/neonate with later-stage use, and close monitoring 24–48 hours after birth is required. Should only be used during pregnancy if the benefits for the mother outweigh the risks for the foetus. Excreted in breast milk in small amounts; caution in breast-feeding women (§4.6).

Labetalol (IV — Hypertensive Emergency)

Brand names: Trandate

Intravenous labetalol is a combined alpha- and beta-adrenoceptor blocker used in hypertensive emergencies, including in pregnancy, to achieve controlled lowering of blood pressure.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: Severe hypertension — bolus: 50 mg by intravenous injection given over 1 minute, repeated at 5-minute intervals if necessary until a satisfactory response occurs. Infusion: a 1 mg/mL solution (200 mg diluted to 200 mL) infused at a rate normally about 160 mg/hour, adjusted according to response

Route: Intravenous injection (over 1 minute) or intravenous infusion — for IV use in hospitalised patients

Frequency: Bolus may be repeated at 5-minute intervals until satisfactory response; infusion continued until a satisfactory response is obtained

Max: Total bolus dose should not exceed 200 mg

eMC §4.2 (Labetalol 100 mg/20 mL solution for injection/infusion, 5 mg/mL). Maximum effect of a bolus usually occurs within 5 minutes; duration of action usually about 6 hours but may be as long as 18 hours. For infusion the effective dose is usually 50 to 200 mg, but the infusion should be continued until a satisfactory response is obtained and larger doses may be needed, especially in patients with phaeochromocytoma. SEVERE HYPERTENSION OF PREGNANCY: a slower and increasing rate of infusion should be used — start at 20 mg/hour, then double every 30 minutes until a satisfactory response is obtained or a dosage of 160 mg/hour is reached. HYPERTENSION DUE TO OTHER CAUSES: infuse at 120–160 mg/hour until a satisfactory response is obtained, then stop the infusion. CONTROLLED HYPOTENSION DURING ANAESTHESIA: recommended starting dose 10 to 20 mg intravenously depending on the age and condition of the patient; if satisfactory hypotension is not achieved after 5 minutes, give increments of 5 to 10 mg until the desired blood pressure is attained (mean duration of hypotension after 20–25 mg is 50 minutes). Patients should always receive the product whilst in the supine or left lateral position, and raising the patient upright within 3 hours of IV administration should be avoided since excessive postural hypotension may occur. Paediatric: safety and efficacy in patients aged 0 to 18 years have not been established; no data are available (§4.2).

Dose adjustments

Renal

Caution is advised when labetalol is used in patients with severe renal impairment (GFR 15–29 mL/min/1.73 m²); no specific dose reduction is stated (§4.4).

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity to labetalol or to any of the excipients
Asthma or a history of obstructive airway disease (non-selective beta-blockers should not be used)
Second or third degree heart block (unless a pacemaker is in situ); sick sinus syndrome including sino-atrial block unless pacemaker in situ; sinus node dysfunction
Cardiogenic shock and other conditions associated with severe and prolonged hypotension, or severe bradycardia
Uncompensated heart failure; unstable/uncontrolled heart insufficiency
Prinzmetal angina
Untreated phaeochromocytoma

Side effects

Postural hypotension (common; pronounced if the patient assumes the upright position within 3 hours of injection)
Congestive heart failure (common); bradycardia (rare); heart block (very rare)
Hypersensitivity and drug fever (common); rash, pruritus, dyspnoea, rarely angioedema
Raised liver function tests (common); very rarely hepatitis, hepatocellular or cholestatic jaundice, hepatic necrosis
Nasal congestion (common); bronchospasm (uncommon); erectile dysfunction (common)

Interactions

Adrenaline — a reduced dose of adrenaline should be used, as concomitant administration with labetalol may result in bradycardia and hypertension; patients on beta-blockers with a history of severe anaphylaxis may be unresponsive to the usual doses of adrenaline (§4.4)
Insulin and oral hypoglycaemic agents — their hypoglycaemic effect may be enhanced, and labetalol may mask the symptoms of hypoglycaemia (tachycardia and tremor) (§4.4)
Full §4.5 interactions section was not captured in this bundle — clinician to review the SPC interactions section directly

Clinical monograph

How it works

It blocks beta-1, beta-2 and alpha-1 adrenoceptors, reducing peripheral vascular resistance and limiting reflex tachycardia, producing a smooth fall in blood pressure.

Prescribing in practice

Lower blood pressure in a controlled, gradual manner with continuous monitoring, as abrupt large reductions can cause organ hypoperfusion; patients should remain supine during and after administration.
Avoid in asthma, decompensated heart failure, significant bradycardia and high-degree heart block, in keeping with its beta-blocking action.
It can cause significant postural hypotension and may mask the warning signs of hypoglycaemia.

Monitoring

Monitor blood pressure and heart rate continuously, and assess for postural hypotension before mobilising the patient.

Counselling the patient

This drip lowers very high blood pressure in a steady, controlled way.
Stay lying down as instructed to avoid dizziness.
Tell staff if you feel faint, wheezy or notice a very slow heartbeat.

Evidence & guidelines

Intravenous labetalol for hypertensive emergencies, including in pregnancy, is supported by NICE guidance.

Reference: NICE NG133 Hypertension in Pregnancy; ESC Hypertension Guidelines; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways

📚 MRCEM Revision

Featured in these MRCEM clinical pathways

Labetalol (IV — Hypertensive Emergency) is a core drug in the following exam-focused workups on our sister siteReviseMRCEM.

MRCEM Primary / Intermediate / OSCE candidates: each pathway includes exam-style questions, RCEM/NICE citations, and FAQ summaries.