Combined Alpha-1 and Beta-Adrenergic Blocker Pregnancy: Based on experience during human pregnancy, labetalol is not expected to increase the risk of congenital malformations, but labetalol crosses the placenta and adverse effects on the foetus and neonate in later pregnancy (bradycardia, hypotension, respiratory depression, hypoglycaemia) should be borne in mind, with close monitoring 24-48 hours after birth. Beta-blockers may reduce uterine blood flow. Use during pregnancy only if the benefits for the mother outweigh the risks for the foetus. Excreted in breast milk in small amounts — caution when breast-feeding.

Labetalol (IV — Hypertensive Emergency)

Brand names: Trandate

Used in: Pre-eclampsia & Obstetric Emergencies

Labetalol is a combined alpha- and beta-blocker used for hypertension — notably in pregnancy (first-line) and, intravenously, for hypertensive emergencies.

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 injection: 50 mg by intravenous injection over 1 minute, repeated at 5-minute intervals if necessary until a satisfactory response occurs

Route: Intravenous injection or intravenous infusion — for IV use in hospitalised patients only

Frequency: Bolus repeated at 5-minute intervals as required; or by continuous intravenous infusion titrated to response

Max: The total bolus dose should not exceed 200 mg

Source quote (eMC §4.2): 'If it is essential to reduce the blood pressure quickly a dose of 50 mg should be given by I.V. injection (during 1 minute) and, if necessary, be repeated at 5-minute intervals until a satisfactory response occurs. The total dose should not exceed 200 mg.' Maximum effect usually occurs within 5 minutes; duration of action usually about 6 hours but may be as long as 18 hours. INTRAVENOUS INFUSION (severe hypertension): use a 1 mg/ml solution (two 20 ml ampoules, 200 mg, diluted to 200 ml with a compatible infusion fluid). The infusion rate will normally be about 160 mg/h but may be adjusted according to response; the effective dose is usually 50 to 200 mg, and larger doses may be needed, especially in patients with phaeochromocytoma. SEVERE HYPERTENSION OF PREGNANCY: use a slower, increasing rate of infusion — start at 20 mg/h, then double every 30 minutes until a satisfactory response is obtained or a dosage of 160 mg/h is reached. HYPERTENSION DUE TO OTHER CAUSES: infuse at a rate of 120-160 mg/h 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 following 20 to 25 mg is 50 minutes). ADMINISTRATION PRECAUTION: patients should always receive labetalol whilst in the supine or left lateral position, and raising the patient into the upright position within 3 hours of IV administration should be avoided since excessive postural hypotension may occur. PAEDIATRIC: the safety and efficacy of labetalol in paediatric patients aged 0 to 18 years have not been established and no data are available — verify any paediatric use against a children's formulary. HEPATIC: particular care in hepatic impairment as these patients metabolise labetalol more slowly.

Dose adjustments

Renal

eMC §4.4: caution is advised when labetalol is used for patients with severe renal impairment (GFR 15-29 mL/min/1.73 m²). No specific IV dose reduction is stated.

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.

US labelling (FDA)

Reference — US labelling, may differ from UK

DOSAGE AND ADMINISTRATION DOSAGE MUST BE INDIVIDUALIZED. The recommended initial dosage is 100 mg twice daily whether used alone or added to a diuretic regimen. After 2 or 3 days, using standing blood pressure as an indicator, dosage may be titrated in increments of 100 mg b.i.d.(twice daily) every 2 or 3 days. The usual maintenance dosage of labetalol hydrochloride tablets is between 200 mg and 400 mg twice daily. Since the full antihypertensive effect of labetalol hydrochloride tablets is usually seen within the first 1 to 3 hours of the initial dose or dose increment, the assurance of a lack of an exaggerated hypotensive response can be clinically established in the office setting. The …

Source: US FDA prescribing information (openFDA / DailyMed), label dated 2026-05-22. Accessed 2026-06-12. US dosing and indications can differ from UK practice — use UK sources for prescribing decisions.

Contraindications

Known hypersensitivity to the active substance 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)
Cardiogenic shock and other conditions associated with severe and prolonged hypotension or severe bradycardia
Uncompensated heart failure; unstable/uncontrolled heart insufficiency
Sick sinus syndrome (including sino-atrial block) unless a pacemaker is in situ; sinus node dysfunction
Prinzmetal angina
Untreated phaeochromocytoma

Side effects

Postural hypotension (common; pronounced postural hypotension may occur if patients assume the upright position within 3 hours of receiving labetalol injection)
Congestive heart failure (common); bradycardia (rare); heart block (very rare)
Hypersensitivity and drug fever (common); reported reactions include rash, pruritus, dyspnoea and very rarely angioedema
Raised liver function tests (common); very rarely hepatitis, hepatocellular or cholestatic jaundice and hepatic necrosis
Nasal congestion (common); bronchospasm (uncommon)
Erectile dysfunction (common)

Interactions

Adrenaline — if patients receiving labetalol require adrenaline treatment, a reduced dose of adrenaline should be used, as concomitant administration may result in bradycardia and hypertension (eMC §4.4)
Insulin and oral hypoglycaemic agents — their hypoglycaemic effect may be enhanced by beta blockers, and labetalol may mask the symptoms of hypoglycaemia (tachycardia and tremor) (eMC §4.4)
NOTE: the fetched eMC bundle did not include §4.5; the entries above are drawn from §4.4 and the full §4.5 interaction list must be checked against the UK SPC

Clinical monograph

How it works

It blocks alpha-1 and beta adrenoceptors, lowering blood pressure through reduced vascular resistance and cardiac effects.

Prescribing in practice

It is first-line for hypertension in pregnancy and for many hypertensive emergencies; intravenous use requires close blood-pressure monitoring.
Avoid in asthma (beta-blockade can cause bronchospasm).
Postural hypotension can occur; rare hepatotoxicity is reported.

Monitoring

Monitor blood pressure (and the fetus in pregnancy where relevant); during IV use monitor closely.

Counselling the patient

Report wheeze or marked dizziness.
Take care standing up, especially early in treatment.

Evidence & guidelines

First-line for hypertension in pregnancy (NICE NG133) and used intravenously in hypertensive emergencies.

Reference: NICE NG133 (Hypertension in Pregnancy); ESC Aortic Diseases Guidelines 2014; MHRA SPC Trandate; AHA/ACC Hypertensive Crisis Guidelines 2017; 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