Labetalol
Prescription ·Exploratory record · not publication-reviewed ·Updated July 13, 2026
Labetalol is a combined nonselective beta-adrenergic and selective alpha-1 adrenergic receptor blocker used to treat hypertension, including hypertensive emergencies and chronic hypertension in pregnancy. It is available in oral and intravenous forms and lowers blood pressure without typically causing reflex tachycardia. It is one of the preferred antihypertensives during pregnancy because of an extensive safety record.
Exploratory record, not a reviewed medical publication.
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What the research says.
A quick, data-only summary. The full evidence, dosing, and sources are below.
Labetalol is a combined nonselective beta-adrenergic and selective alpha-1 adrenergic receptor blocker used to treat hypertension, including hypertensive emergencies and chronic hypertension in pregnancy. NutriStack rates the supporting evidence as strong. Common adult dosing is Oral: initial 100 mg twice daily, titrated to 200-400 mg twice daily; usual maintenance 200-800 mg/day in divided doses, maximum 2,400 mg/day. IV (hypertensive emergency): 20 mg slow injection, then 40-80 mg every 10 minutes as needed (max 300 mg) or infusion at 0.5-2 mg/min., though a prescriber sets the actual dose. With long-term use it can deplete coenzyme q10. This profile indexes 4 sources.
- Dizziness and orthostatic hypotension
- Fatigue and tiredness
- Nausea
- Bronchial asthma or severe reactive airway disease
- Overt cardiac failure
The bottom line
Evidence rating strong. Most-documented uses: treatment of chronic essential hypertension, management of hypertension in pregnancy and preeclampsia, control of hypertensive emergencies and urgencies (intravenous). 4 sources indexed (1977–2021), with 0 interaction records on file.
How it works, mechanistically.
Core mechanism
Labetalol blocks both beta-1 and beta-2 adrenergic receptors (nonselective beta blockade) and selectively blocks alpha-1 adrenergic receptors. Alpha-1 blockade produces peripheral arterial vasodilation and reduces systemic vascular resistance, while beta blockade attenuates the reflex sympathetic drive (tachycardia and increased cardiac output) that vasodilation would otherwise trigger. The net effect is a fall in blood pressure with relatively little change in resting heart rate and cardiac output. The oral alpha-to-beta blocking ratio is approximately 1:3 and the intravenous ratio is approximately 1:7.1,4
Dosing & protocol.
Labetalol is well absorbed orally but undergoes extensive first-pass hepatic metabolism, giving an absolute bioavailability of roughly 25 percent. Food increases bioavailability somewhat, so taking it consistently with or without food is advised; dosing with meals can improve tolerability.2
What it depletes.
Nutrients this medication can lower over time, and what to replace.
Coenzyme Q10
MildLike other beta-adrenergic blocking agents, labetalol can inhibit Coenzyme Q10 (ubiquinone)-dependent enzymes and reduce CoQ10-related mitochondrial activity, which may lower tissue and circulating CoQ10. CoQ10 shares structural similarity with the beta-blocker pharmacophore, and beta-blockade has been associated with reduced CoQ10-dependent respiratory chain function; this is considered a class effect rather than one specific to labetalol.
Full safety detail.
Side effects
- Dizziness and orthostatic hypotension
- Fatigue and tiredness
- Nausea
- Scalp tingling or paresthesia (especially early in treatment)
- Bradycardia
- Nasal congestion
- Bronchospasm in susceptible patients
- Masking of hypoglycemia warning signs (tachycardia, tremor) in diabetics
- Hepatic injury (rare, can be severe)
- Sexual dysfunction
Sources, by evidence tier.
Numbered references. Citations throughout the page link here.
Reviews & position papers
1- 1Effect of beta-adrenergic blockade on the symptomatic and counterregulatory response to hypoglycemiaVarious · Pharmacology review literature · 2016
Beta blockade can mask sympathetic warning signs of hypoglycemia, though sweating may persist.
Reference material
3- 2Labetalol hydrochloride tablets and injection prescribing information (FDA label)U.S. Food and Drug Administration · FDA Prescribing Information · 2021
Labetalol produces dose-related falls in blood pressure through combined alpha-1 and beta blockade without substantial reflex tachycardia.
- 3Gestational Hypertension and Preeclampsia (ACOG Practice Bulletin No. 222)American College of Obstetricians and Gynecologists · Obstetrics and Gynecology · 2020
Labetalol is recommended as a first-line agent for acute and chronic management of hypertension in pregnancy.
- 4Inhibition of coenzyme Q10-enzymes by clinically used adrenergic blockers of beta-receptorsKishi T, Watanabe T, Folkers K · Research Communications in Chemical Pathology and Pharmacology · 1977
Several beta-blocking drugs inhibited CoQ10-dependent mitochondrial enzymes in vitro, a proposed mechanism for reduced CoQ10 status.
Common questions.
Quick answers about Labetalol, drawn from the data on this page.
What is Labetalol?
Labetalol is a combined nonselective beta-adrenergic and selective alpha-1 adrenergic receptor blocker used to treat hypertension, including hypertensive emergencies and chronic hypertension in pregnancy. It is available in oral and intravenous forms and lowers blood pressure without typically causing reflex tachycardia. It is one of the preferred antihypertensives during pregnancy because of an extensive safety record.
What is Labetalol used for?
Commonly cited benefits of Labetalol include: Treatment of chronic essential hypertension; Management of hypertension in pregnancy and preeclampsia; Control of hypertensive emergencies and urgencies (intravenous); Blood pressure control in pheochromocytoma and clonidine withdrawal. NutriStack rates the overall evidence as strong.
What is a typical dose of Labetalol?
A typical adult dose of Labetalol is Oral: initial 100 mg twice daily, titrated to 200-400 mg twice daily; usual maintenance 200-800 mg/day in divided doses, maximum 2,400 mg/day. IV (hypertensive emergency): 20 mg slow injection, then 40-80 mg every 10 minutes as needed (max 300 mg) or infusion at 0.5-2 mg/min.. The commonly recommended form is Oral tablet for chronic hypertension; intravenous injection or infusion for hypertensive emergencies and inpatient pregnancy management. These are general ranges, not personalized advice; confirm the right dose with a clinician.
What are the side effects of Labetalol?
Reported side effects include dizziness and orthostatic hypotension, fatigue and tiredness, nausea, scalp tingling or paresthesia (especially early in treatment), bradycardia, nasal congestion. This is educational information; check with a healthcare professional before use.
How strong is the evidence for Labetalol?
NutriStack rates this as Strong, meaning multiple high-quality meta-analyses or systematic reviews converge on the same finding. Full tier criteria are at https://nutristackapp.com/methodology/evidence-tiers.
Use this with your stack
Labetalol in NutriStack.
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