Labetalol hydrochloride

What it is

Labetalol is a blood-pressure drug that blocks two kinds of adrenaline receptor at once: alpha-1 receptors on blood vessels, which relaxes them, and beta receptors on the heart, which slows the heart's response to adrenaline. It is given as a tablet for ongoing high blood pressure and as an intravenous injection for severe high blood pressure. Only about a quarter of an oral dose reaches the circulation because the liver removes most of it on the first pass, and that fraction rises when the drug is taken with food.

What the research says

For lowering blood pressure it works, and the label documents the dose-response in detail. The harder question is what that buys. A Cochrane review of beta-blockers as first-line treatment for hypertension found only modest cardiovascular benefit, no mortality benefit, and worse results than calcium-channel blockers - though three-quarters of the participants were taking atenolol, not labetalol. In pregnancy the evidence is stronger and more specific: treating mild chronic hypertension improved pregnancy outcomes in the CHAP trial, and a Cochrane review found antihypertensive drugs roughly halve the risk of developing severe hypertension. Against that sit a documented risk of liver injury, low blood pressure on standing, bronchospasm, and low blood sugar and slow heart rate in newborns exposed before birth.

Evidence grade: Well established.

How it works

Drug class: Combined alpha-1 and non-selective beta-adrenergic receptor blocker

Labetalol blocks alpha-1 receptors, which widens blood vessels and lowers the resistance blood has to push against, and simultaneously blocks beta-1 and beta-2 receptors, which stops the heart from speeding up in compensation. The label records that the alpha-blockade was shown in people by blunting the pressor response to phenylephrine and to the cold pressor test, and the beta-blockade by a small fall in resting heart rate and blunted exercise tachycardia. Because the alpha-blockade is stronger standing than lying, blood pressure falls more in the standing position. (Source 1)

What it is used for

• Labetalol lowers blood pressure in a dose-related way, which the label documents. For hard outcomes the evidence comes from beta-blockers as a class, where a Cochrane review of 13 trials and over 40,000 participants found no mortality benefit against placebo, a modest cardiovascular benefit driven by stroke, and worse outcomes than calcium-channel blockers - with three-quarters of participants on atenolol rather than labetalol. Evidence: limited. (Source 2)
• The injection is approved for control of blood pressure in severe hypertension. In the largest randomised comparison of oral drugs for severe hypertension in pregnancy, oral labetalol brought blood pressure into range within 6 hours in 77% of women, similar to methyldopa and not statistically different from nifedipine retard. Evidence: limited. (Source 3)
• The tablet label's indication is hypertension generally, with pregnancy use governed only by a Pregnancy Category C statement, so use specifically in pregnancy is off-label. The CHAP trial found that treating mild chronic hypertension to a target below 140/90 mm Hg lowered the primary composite outcome from 37.0% to 30.2% with no increase in small-for-gestational-age births, and a target-trial-emulation study of 6,724 pregnancies found labetalol and nifedipine similar. Evidence: established. (Source 4)
• In a 894-woman open-label randomised trial in India, oral labetalol achieved the primary outcome of blood-pressure control within 6 hours without adverse outcomes in 228 of 295 women (77%), against 249 of 298 (84%) on nifedipine retard (p=0.05) and 230 of 301 (76%) on methyldopa (p=0.80 versus labetalol). Evidence: limited. (Source 3)
• The label records that intravenous labetalol has been effective at lowering blood pressure and relieving symptoms in pheochromocytoma, but that paradoxical hypertensive responses have been reported in a few patients with the tumour, and advises caution. Evidence: disputed. (Source 5)

Interactions

• Alcohol (clinical trial): No study of alcohol with labetalol was found. What is documented is that short-term alcohol intake by itself causes blood pressure to fall when upright, because it stops blood vessels from constricting in response to standing: in 14 healthy volunteers, the systolic fall at the strongest orthostatic stress was 14 mm Hg after alcohol against 7 mm Hg after placebo. Labetalol lowers standing blood pressure through the same mechanism it blocks, so the two effects point the same way. (Source 6)
• Alcohol, in someone taking an alpha-1 blocker (clinical trial): The closest measured evidence is not about labetalol. Ten Japanese men with mild high blood pressure were given about 1 mL of alcohol per kilogram of body weight - about 70 mL of alcohol for a 70 kg man, well above a single drink - with an evening meal, once before and once after five to seven days on prazosin, a different alpha-1 blocker, at 1 mg three times a day. After prazosin the fall in blood pressure two to four hours after drinking was larger, and the difference reached statistical significance for the diastolic reading only (P < .05). Labetalol blocks alpha-1 receptors as well as beta receptors, which is why this is the nearest study, but it tested a different drug in ten people and not labetalol. Limit: This is ten patients, on prazosin rather than labetalol, in a single-centre before-and-after study with no randomised comparison group, so it cannot give a size of effect for labetalol or for alpha-1 blockers as a class. The paper's own closing sentences generalise to the whole alpha-1 blocker class and to a population; those sentences are deliberately not quoted here, both because ten patients on one drug cannot support a class claim and because the 2000 abstract uses racial wording that is no longer acceptable. Only the diastolic difference was significant; the systolic figures (-18.0 +/- 3.7 against -24.4 +/- 4.9 mm Hg) are reported without a significance claim. (Source 7)
• Food (pharmacokinetic study): Taking labetalol with food raises the fraction of the dose that reaches the bloodstream, because food reduces the amount the liver removes on first pass. The label states this plainly. (Source 8)
• Cimetidine (pharmacokinetic study): Cimetidine raises the amount of labetalol reaching the bloodstream, either by increasing absorption or by changing how the liver breaks it down, so more drug is present for the same dose. (Source 9)
• Beta-agonist bronchodilators (asthma inhalers) (label): Drugs that block beta receptors blunt the airway-opening effect of beta-agonist inhalers, so higher than normal anti-asthmatic doses may be needed. (Source 9)
• Halothane anaesthesia (clinical trial): Labetalol and halothane act together to lower blood pressure more than either alone, and the label warns that high halothane concentrations should not be used with intravenous labetalol because of excessive hypotension, a large fall in cardiac output and a rise in central venous pressure. (Source 9)
• Digitalis glycosides and verapamil-type calcium antagonists (label): Both digitalis and beta-blockers slow conduction through the atrioventricular node and reduce heart rate, so taking them together increases the risk of a dangerously slow heart. The label also advises care with verapamil-type calcium antagonists. (Source 9)
• Tricyclic antidepressants (case reports): In one survey, tremor was reported in 2.3% of patients taking labetalol with a tricyclic antidepressant against 0.7% on labetalol alone. The label says the contribution of each treatment is unknown but an interaction cannot be excluded. (Source 9)
• Epinephrine (adrenaline) given for a severe allergic reaction (label): People with a history of severe anaphylactic reaction who are taking a beta-blocker may react more strongly on being exposed to an allergen again, and the label states that they may not respond to the usual doses of epinephrine used to treat an allergic reaction. This is the only statement in the label's drug-interactions section that bears on emergency treatment. Limit: The label writes this as a beta-blocker class statement rather than as a labetalol measurement, and it gives no rate and no study behind it. (Source 9)

Stopping it

• Stopping a beta-blocker abruptly has its own risk. The labetalol label records that although angina has not been reported on stopping labetalol itself, hypersensitivity to catecholamines has been seen in people withdrawn from beta-blocker therapy, and that exacerbation of angina and in some cases myocardial infarction have followed abrupt discontinuation. It directs that when labetalol is stopped in people with ischaemic heart disease the dose be reduced gradually over 1 to 2 weeks with careful monitoring, and that because coronary artery disease is common and may be unrecognised it may be prudent not to stop abruptly even when treating hypertension. (Source 10)
• The label's patient information section states the practical rule: dosing should not be interrupted or stopped without a physician's advice. (Source 11)
• For the related question of planned deprescribing, a 2026 systematic review and meta-analysis of 10 studies in 121,114 people after myocardial infarction found that stopping a beta-blocker in those with preserved ejection fraction might not raise mortality or reinfarction, but might raise major adverse cardiovascular events, driven by cardiovascular hospitalisations, all at low certainty. Nine of the ten studies were observational. (Source 12)
• If liver injury appears, the label's instruction is not a taper but a permanent stop. (Source 13)

What goes wrong

In the label's own placebo-controlled trials, dizziness and nausea were several times more common on labetalol than on placebo. (Source 14)

• Randomized trial, Moderate certainty.
• Size: Labetalol N=227, placebo N=98, propranolol N=84, metoprolol N=49.
• Who: Hypertensive patients in multicentre controlled clinical trials, a group excluding people with bronchospastic disease or overt congestive heart failure.
• How long: Treatment periods of 3 and 4 months.
• Result: Rates considered probably drug related, labetalol versus placebo: dizziness 11% versus 3%, nausea 6% versus 1%, fatigue 5% versus 0%, dyspepsia 3% versus 1%, nasal stuffiness 3% versus 0%, ejaculation failure 2% versus 0%, postural hypotension 1% versus 0%, bradycardia 0% versus 0%. If all reports rather than only probably-related ones are counted, the label states the rates are higher (dizziness 20%, nausea 14%, fatigue 11%). Discontinuation for adverse effects was required in 7% of labetalol patients, against 8% to 10% for the pure beta-blockers and 30% for a centrally acting alpha-agonist.
• Funding: manufacturer-run registration trials recorded in the label.

Limit of this finding: The label prints two different figures for the same events: the table gives dizziness as 11% and nausea as 6% on the restricted 'probably drug related' definition, while the surrounding text says that counting all reports gives dizziness 20%, nausea 14% and fatigue 11%. A reader should not treat either set as the single rate, and the placebo group of 98 is small. Two more cautions about this table. The sentence introducing the dose-response table says 'Certain of the side effects increased with increasing dose', but the label's own 900 mg column (117 patients) moves the other way - dizziness 1% at 900 mg against 5% at 800 mg and 9% at 1,200 mg, and nausea, dyspepsia and ejaculation failure all 0% at 900 mg - so the dose-response statement is not supported by the figures printed beneath it. And the 'Potential Adverse Effects' list further down the section (mental depression progressing to catatonia, agranulocytosis, purpura, mesenteric artery thrombosis, ischemic colitis, laryngospasm) is not labetalol's: the label introduces it by saying these effects 'have been reported with other beta-adrenergic blocking agents'. Separately, this table gives postural hypotension as 1% while the label's Pharmacodynamics section gives 2% for the same thing, and the label never reconciles the two.

Labetalol Hydrochloride (N=227) % Placebo (N=98) % Propranolol (N=84) % Metoprolol (N=49) % Body as a whole Fatigue 5 0 12 12 Asthenia 1 1 1 0 Headache 2 1 1 2 Gastrointestinal Nausea 6 1 1 2 Vomiting <1 0 0 0 Dyspepsia 3 1 1 0 Abdominal pain 0 0 1 2 Diarrhea <1 0 2 0 Taste distortion 1 0 0 0 Central and Peripheral Nervous Systems Dizziness 11 3 4 4 Paresthesias <1 0 0 0 Drowsiness <1 2 2 2

Low blood pressure on standing is common after intravenous labetalol if the patient sits or stands up too soon. (Source 15)

• Randomized trial, Moderate certainty.
• Size: Controlled trials involving 92 patients, with incidence figures given per 100 patients.
• Who: Patients given labetalol injection.
• How long: Within 3 hours of the injection.
• Result: The figures in this section are not on one denominator and must be read separately. Symptomatic postural hypotension is given as an incidence of 58%, but only as a conditional figure - it applies to patients tilted or allowed to sit or stand up within 3 hours of the injection - and it is an order of magnitude above every other number in the section. The remaining intravenous figures are given as counts per 100 patients: nausea in 13, dizziness in 9, tingling of the scalp or skin in 7, vomiting in 4, increased sweating in 4, somnolence or yawning in 3, moderate hypotension while supine in 1, flushing in 1, and transient rises in blood urea nitrogen and serum creatinine in 8, those associated with falls in blood pressure and generally in patients with prior renal insufficiency. The percentages in the dose table in the same section are oral labetalol figures, not intravenous ones, and the 4% transaminase figure at the end is explicitly 'Among patients dosed with labetalol tablets'.
• Funding: manufacturer-run trials recorded in the label.

Limit of this finding: The label mixes denominators in this passage: an incidence of 58% is quoted alongside counts 'per 100 patients' while the controlled trials are described as involving 92 patients. The counts and the percentages are not on a single consistent denominator, so individual figures should not be read as precise rates. Four further problems in the label's own text. The controlled trials are described as involving 92 patients, which is fewer than the denominator of 100 that the incidences are expressed against, so those cannot be raw counts from the trial cohort. The 58% is conditional on posture within 3 hours of the dose and is not comparable with the per-100 counts beside it. In the dose table only the first data row is labelled 'Dizziness (%)' and the ten rows under it print bare numbers, so 'Nausea ... 19' is 19 per cent and not 19 patients. And the table itself, plus the closing transaminase figure, are oral labetalol data sitting inside an injection label - the label says so ('The largest experience is with oral labetalol', 'Among patients dosed with labetalol tablets') - so none of those percentages is an intravenous rate. The statement that side effects 'increased with increasing oral dose' is also contradicted by the label's own 900 mg column.

Symptomatic postural hypotension (incidence 58%) is likely to occur if patients are tilted or allowed to assume the upright position within 3 hours of receiving labetalol injection. Moderate hypotension occurred in 1 of 100 patients while supine. Increased sweating was noted in 4 of 100 patients, and flushing occurred in 1 of 100 patients.

Labetalol can cause severe liver injury, and the reporting signal for drug-induced liver injury is far stronger for labetalol than for other beta-blockers. (Source 16)

• Case series, Low certainty.
• Size: One fatal index case plus 27 published case reports; FDA Adverse Event Reporting System data from 2020Q1 to 2025Q1.
• Who: People taking labetalol; predominantly female (about 80%), one-third pregnant or postpartum.
• How long: Latency from 7 to 365 days, median about 60 days.
• Result: Disproportionality signals for drug-induced liver injury: PRR 22.7 (95% CI 15.6-33.1), ROR 23.7 (95% CI 16.0-35.1), IC025 2.5; for autoimmune hepatitis PRR 59.8 (95% CI 34.1-104.8), ROR 60.9 (95% CI 34.4-108.1), IC025 2.8. Signals persisted when the comparator was restricted to other beta-blockers. Outcomes in the case series: full recovery in about 75%, but also liver transplantation and death.
• Funding: not stated in the abstract.

Limit of this finding: Disproportionality analysis of a spontaneous-reporting database measures how often something is reported, not how often it happens. It has no denominator of exposed patients, cannot give an incidence, and is vulnerable to reporting bias - including the possibility that the label's own hepatic-injury warning makes clinicians more likely to report liver events with labetalol. A PRR of 22.7 is a signal to investigate, not a risk estimate.

In the FDA Adverse Event Reporting System (2020Q1-2025Q1), labetalol showed strong disproportionality signals for DILI (PRR 22.7, 95% CI 15.6-33.1; ROR 23.7, 95% CI 16.0-35.1; IC025 2.5) and autoimmune hepatitis (PRR 59.8, 95% CI 34.1-104.8; ROR 60.9, 95% CI 34.4-108.1; IC025 2.8), which persisted when restricted to other β-blockers as comparators.

The label records severe hepatocellular injury, confirmed by rechallenge in at least one case, with hepatic necrosis and death reported. (Source 13)

• Official position, Low certainty.
• Size: not stated.
• Who: Patients taking labetalol.
• How long: After both short- and long-term treatment; may be slowly progressive despite minimal symptoms.
• Result: No rate is given for severe injury. The same label records reversible increases of serum transaminases in 4% of labetalol-treated patients who were tested. The label directs that if there is laboratory evidence of liver injury or jaundice, labetalol should be stopped and not restarted.
• Funding: regulatory label, not a funded study.

Severe hepatocellular injury, confirmed by rechallenge in at least one case, occurs rarely with labetalol therapy. The hepatic injury is usually reversible, but hepatic necrosis and death have been reported. Injury has occurred after both short- and long-term treatment and may be slowly progressive despite minimal symptomatology. Similar hepatic events have been reported with a related research compound, dilevalol HCl, including two deaths. Dilevalol HCl is one of the four isomers of labetalol hydrochloride. Thus, for patients taking labetalol, periodic determination of suitable hepatic laboratory tests would be appropriate. Appropriate laboratory testing should be done at the first symptom or sign of liver dysfunction (e.g., pruritus, dark urine, persistent anorexia, jaundice, right upper quadrant tenderness, or unexplained "flu-like" symptoms). If the patient has laboratory evidence of liver injury or jaundice, labetalol should be stopped and not restarted.

Babies exposed to beta-blockers before birth probably have a higher risk of low blood sugar and possibly of a slow heart rate. (Source 17)

• Systematic review, Moderate certainty.
• Size: 55 studies included from 1,043 screened articles.
• Who: Neonates exposed to beta-blockers in utero or during lactation, in observational studies and randomised controlled trials.
• How long: Neonatal period; the authors suggest glucose monitoring until 24 hours after birth.
• Result: No pooled effect size is given in the abstract. The meta-analysis found a probable risk of hypoglycaemia (certainty of evidence moderate) and a possible risk of bradycardia (certainty of evidence low).
• Funding: not stated in the abstract.

Limit of this finding: This is a class finding across beta-blockers, not labetalol alone, and the abstract reports no numerical risk estimates, so the size of the risk cannot be read from it. The labetalol label independently records hypotension, bradycardia, hypoglycaemia and respiratory depression in infants of mothers treated during pregnancy.

Our meta-analysis showed a probable risk of hypoglycemia (CoE-Moderate) and possible risk of bradycardia (CoE-Low) in neonates upon fetal beta-blocker exposure. Therefore, we suggest the monitoring of glucose levels in exposed neonates until 24 h after birth. Due to the limited clinical implication, monitoring of the heart rate could be considered for 24 h.

The label records hypotension, bradycardia, hypoglycaemia and respiratory depression in infants of mothers treated with labetalol during pregnancy. (Source 18)

• Official position, Low certainty.
• Size: not stated.
• Who: Infants of mothers treated with labetalol for hypertension during pregnancy.
• How long: Neonatal.
• Result: No rates are given. The label also records that oral labetalol given to rats during late gestation through weaning at two to four times the maximum recommended human dose decreased neonatal survival.
• Funding: regulatory label, not a funded study.

Limit of this finding: The second half of this label passage is a rat finding and is not a human finding.

Hypotension, bradycardia, hypoglycemia, and respiratory depression have been reported in infants of mothers who were treated with labetalol hydrochloride for hypertension during pregnancy.

Labetalol is contraindicated in asthma and in obstructive airway disease because beta-blockade can trigger bronchospasm. (Source 19)

• Official position, Certainty not rated.
• Size: not stated.
• Who: People with bronchial asthma or a history of obstructive airway disease.
• How long: not applicable.
• Result: No rates are given. The label lists bronchial asthma among absolute contraindications, states that beta-blockers even with apparent cardioselectivity should not be used in people with a history of obstructive airway disease including asthma, and lists bronchospasm among reported adverse events. The injection label states that labetalol injection at the usual intravenous therapeutic doses has not been studied in patients with nonallergic bronchospastic disease and should not be used in them.
• Funding: regulatory label, not a funded study.

Limit of this finding: The same label contradicts itself here, and a reader should know. CONTRAINDICATIONS states labetalol 'is contraindicated in bronchial asthma' and that beta-blockers 'should not be used in patients with a history of obstructive airway disease, including asthma'. A paragraph inside WARNINGS says the opposite for the same people: that labetalol 'may be used with caution, however, in patients who do not respond to, or cannot tolerate, other antihypertensive agents'. The label never reconciles the flat contraindication with the permitted-with-caution statement, so this is a decision for a prescriber who knows the person, not something the label settles.

Labetalol hydrochloride is contraindicated in bronchial asthma, overt cardiac failure, greater-than-first-degree heart block, cardiogenic shock, severe bradycardia, other conditions associated with severe and prolonged hypotension, and in patients with a history of hypersensitivity to any component of the product (see WARNINGS ). Beta-blockers, even those with apparent cardioselectivity, should not be used in patients with a history of obstructive airway disease, including asthma.

Beta-blockade can hide the warning signs of low blood sugar and make severe hypoglycaemia more likely. (Source 20)

• Official position, Certainty not rated.
• Size: not stated.
• Who: People with diabetes mellitus, children, and people who are fasting or vomiting.
• How long: Any time during treatment.
• Result: No rates are given. The label states beta-blockers may prevent early warning signs such as tachycardia and increase the risk for severe or prolonged hypoglycaemia at any time during treatment. The injection label adds that beta-blockade reduces insulin release in response to hyperglycaemia and that antidiabetic drug doses may need adjusting.
• Funding: regulatory label, not a funded study.

Limit of this finding: One wrinkle in the label: this warning names children among those at risk of severe or prolonged hypoglycaemia, while the same label's Pediatric Use section states that safety and effectiveness in children have not been established. The warning is not an indication that the drug is intended for children.

Beta-blockers may prevent early warning signs of hypoglycemia, such as tachycardia, and increase the risk for severe or prolonged hypoglycemia at any time during treatment, especially in patients with diabetes mellitus or children and patients who are fasting (i.e., surgery, not eating regularly, or are vomiting). If severe hypoglycemia occurs, patients should be instructed to seek emergency treatment.

What the evidence supports

Treating mild chronic hypertension in pregnancy to a target below 140/90 mm Hg improved pregnancy outcomes without slowing fetal growth. (Source 4)

• Randomized trial, High certainty.
• Size: 2408 women.
• Who: Pregnant women with mild chronic hypertension (below 160/100 mm Hg) and singleton fetuses at under 23 weeks' gestation.
• How long: Pregnancy to delivery.
• Result: Primary composite outcome (preeclampsia with severe features, medically indicated preterm birth before 35 weeks, placental abruption, or fetal or neonatal death) 30.2% with active treatment versus 37.0% with control, adjusted risk ratio 0.82 (95% CI 0.74 to 0.92; P<0.001) - an absolute reduction of 6.8 percentage points, about 15 women treated to prevent one event (absolute figures computed by us from the proportions the paper prints). Small-for-gestational-age birth weight below the 10th percentile 11.2% versus 10.4% (adjusted risk ratio 1.04, 95% CI 0.82 to 1.31; P = 0.76). Any preeclampsia 24.4% versus 31.1% (RR 0.79, 95% CI 0.69 to 0.89). Serious maternal complications 2.1% versus 2.8% (RR 0.75, 95% CI 0.45 to 1.26).
• Funding: independent - funded by the National Heart, Lung, and Blood Institute.

Limit of this finding: CHAP tested a treatment strategy, not labetalol specifically. The protocol allowed any antihypertensive recommended for use in pregnancy, and the published abstract does not say what share of women received labetalol, so the result cannot be attributed to labetalol alone. The trial was also open-label.

The incidence of a primary-outcome event was lower in the active-treatment group than in the control group (30.2% vs. 37.0%), for an adjusted risk ratio of 0.82 (95% confidence interval [CI], 0.74 to 0.92; P<0.001).

What the evidence does not support

In the largest randomised comparison of oral drugs for severe hypertension in pregnancy, labetalol was not better than nifedipine retard or methyldopa. (Source 3)

• Randomized trial, Moderate certainty.
• Size: 894 women randomised and analysed by intention to treat (298 nifedipine, 295 labetalol, 301 methyldopa)
• Who: Pregnant women at least 18 years old, at least 28 weeks' gestation, with systolic blood pressure at or above 160 mm Hg or diastolic at or above 110 mm Hg, in two public hospitals in Nagpur, India.
• How long: Primary outcome within 6 hours.
• Result: Primary outcome (blood pressure 120-150 systolic and 70-100 diastolic within 6 hours with no adverse outcomes) achieved in 228 of 295 (77%) on labetalol, 249 of 298 (84%) on nifedipine retard and 230 of 301 (76%) on methyldopa. Nifedipine beat methyldopa (p=0.03) but the nifedipine versus labetalol comparison did not reach significance (p=0.05) and labetalol versus methyldopa did not differ (p=0.80). Seven serious adverse events in total (1% of births): one intrapartum seizure in the labetalol group and six stillbirths across the three groups.
• Funding: independent - PREEMPT at the University of British Columbia, a grantee of the Bill & Melinda Gates Foundation.

Limit of this finding: This was an open-label trial with different dose-escalation protocols in each arm (labetalol and nifedipine could be escalated hourly, methyldopa was a single dose with no escalation), so part of any difference may reflect the regimen rather than the drug. The nifedipine-versus-labetalol p value of 0.05 sits exactly on the conventional threshold and the paper describes it as not differing. Worth being blunt about the framing: the paper calls an 8-percentage-point difference at p=0.03 significant and a 7-percentage-point difference at p=0.05 'did not differ'. That is a threshold decision rather than a demonstration of equivalence, so this should be read as 'no clear difference was shown between labetalol and nifedipine', not as 'labetalol and nifedipine were the same'.

The primary outcome was significantly more common in women in the nifedipine group than in those in the methyldopa group (249 [84%] women vs 230 [76%] women; p=0·03). However, the primary outcome did not differ between the nifedipine and labetalol groups (249 [84%] women vs 228 [77%] women; p=0·05) or the labetalol and methyldopa groups (p=0·80).

Beta-blockers as first-line treatment for hypertension showed no mortality benefit over placebo and performed worse than calcium-channel blockers. (Source 2)

• Systematic review, Moderate certainty.
• Size: 13 randomised trials; 40,245 participants taking beta-blockers, three-quarters of them atenolol; comparisons against placebo (4 trials, 23,613 participants), diuretics (5 trials, 18,241), calcium-channel blockers (4 trials, 44,825) and renin-angiotensin system inhibitors (3 trials, 10,828)
• Who: Adults with hypertension, trials of at least one year, conducted between the 1970s and the 2000s.
• How long: At least one year per trial.
• Result: All-cause mortality beta-blockers versus placebo RR 0.99 (95% CI 0.88 to 1.11); versus calcium-channel blockers RR 1.07 (95% CI 1.00 to 1.14). Total cardiovascular disease versus placebo RR 0.88 (95% CI 0.79 to 0.97, low certainty), driven by stroke RR 0.80 (95% CI 0.66 to 0.96) with no difference in coronary heart disease RR 0.93 (95% CI 0.81 to 1.07). Cardiovascular disease was worse than with calcium-channel blockers RR 1.18 (95% CI 1.08 to 1.29). Discontinuation for adverse events was higher than with renin-angiotensin system inhibitors RR 1.41 (95% CI 1.29 to 1.54).
• Funding: not stated in the abstract.

Limit of this finding: Three-quarters of the beta-blocker participants took atenolol and the review found no outcome trials of the newer vasodilating beta-blockers. Labetalol is a combined alpha/beta blocker and is not named in the abstract, so this class result cannot be read directly as a labetalol result. The review also states most of the included trials had a high risk of bias. The review's own counts also do not line up: it opens 'Thirteen RCTs met inclusion criteria' and then lists comparisons of 4, 5, 4 and 3 trials, which comes to 16. Trials contributing to more than one comparison would explain it, but the abstract does not say so, so neither count should be read as the number of trials.

There was no difference in all-cause mortality between beta-blockers and placebo (RR 0.99, 95% CI 0.88 to 1.11), diuretics or RAS inhibitors, but it was higher for beta-blockers compared to CCBs (RR 1.07, 95% CI 1.00 to 1.14). The evidence on mortality was of moderate-certainty for all comparisons.

Where the evidence is mixed

Antihypertensive drug treatment for mild to moderate hypertension in pregnancy roughly halves the risk of developing severe hypertension, but has not been shown to change pre-eclampsia, fetal or neonatal death, small-for-gestational-age birth or preterm birth. (Source 21)

• Systematic review, Moderate certainty.
• Size: 63 trials included, data from 58 trials and 5909 women; the placebo comparison rests on 31 trials and 3485 women.
• Who: Women with mild to moderate hypertension in pregnancy (systolic 140-169 mmHg and/or diastolic 90-109 mmHg)
• How long: Treatment planned for at least seven days.
• Result: Severe hypertension RR 0.49 (95% CI 0.40 to 0.60; 20 trials, 2558 women; moderate certainty). Proteinuria/pre-eclampsia aRR 0.92 (95% CI 0.75 to 1.14; 23 trials, 2851 women; low certainty). Total fetal or neonatal death aRR 0.72 (95% CI 0.50 to 1.04; 29 trials, 3365 women). Small-for-gestational-age aRR 0.96 (95% CI 0.78 to 1.18). Preterm birth under 37 weeks aRR 0.96 (95% CI 0.83 to 1.12). Beta-blockers and calcium-channel blockers pooled were better than methyldopa at avoiding severe hypertension (RR 0.70, 95% CI 0.56 to 0.88; 11 trials, 638 women).
• Funding: not stated in the abstract.

Limit of this finding: The review notes the trials had moderate to high risk of bias overall and that different trials used different drugs, so the pooled result is indirect for labetalol specifically. This block is the review's main-results section only. The review's secondary-outcome sections, which are not quoted here, state that it remains uncertain about maternal death, severe pre-eclampsia, eclampsia and the baby's long-term growth and development, so the absence of a demonstrated effect in the figures above is not the same as a demonstrated absence of effect. The source text also prints 'different hypertensive drugs' where it means antihypertensive drugs, and runs several sentences together without a space after the full stop; both are the source's own and are reproduced as printed.

moderate-certainty evidence suggests that use of antihypertensive drug(s) probably halves the risk of developing severe hypertension (risk ratio (RR) 0.49; 95% confidence interval (CI) 0.40 to 0.60; 20 trials, 2558 women), but may have little or no effect on the risk of proteinuria/pre-eclampsia (average risk ratio (aRR) 0.92; 95% CI 0.75 to 1.14; 23 trials, 2851 women; low-certainty evidence). Moderate-certainty evidence also shows that antihypertensive drug(s) probably have little or no effect in the risk of total reported fetal or neonatal death (including miscarriage) (aRR 0.72; 95% CI 0.50 to 1.04; 29 trials, 3365 women), small-for-gestational-age babies (aRR 0.96; 95% CI 0.78 to 1.18; 21 trials, 2686 babies) or preterm birth less than 37 weeks (aRR 0.96; 95% CI 0.83 to 1.12; 15 trials, 2141 women).

Labetalol and nifedipine performed similarly for chronic hypertension in pregnancy in a large claims-based emulated trial. (Source 22)

• Cohort study, Low certainty.
• Size: 6,724 pregnant individuals (labetalol 5,504, nifedipine 1,220)
• Who: Pregnant people with chronic hypertension in the United States MarketScan commercial claims database, 2007-2022, and their infants.
• How long: Pregnancy to delivery.
• Result: Composite effectiveness outcome (severe preeclampsia/eclampsia, medically indicated preterm birth, placental abruption or stillbirth) 42% on labetalol versus 44% on nifedipine; adjusted RR 1.03 (95% CI 0.96-1.11), adjusted risk difference 1.35 per 100 births (95% CI -1.76 to 4.45). Small-for-gestational-age 13% versus 12%; adjusted RR 0.98 (95% CI 0.82-1.16), adjusted risk difference -0.26 per 100 births (95% CI -2.33 to 1.81).
• Funding: not stated in the abstract.

Limit of this finding: This is an observational target-trial emulation from insurance claims, not a randomised trial, so residual confounding by severity and by prescriber choice cannot be excluded. Claims data also do not capture blood-pressure readings. Read the adjusted figures, not the raw percentages: the crude numbers point the opposite way from the result. The effectiveness outcome was lower in the labetalol group (42% against 44%) while the adjusted risk ratio is 1.03, and the safety outcome was higher with labetalol (13% against 12%) while the adjusted risk ratio is 0.98. That reversal is what the weighting for differences between the two groups does; it is not an inconsistency, but the raw percentages are not the finding.

The effectiveness outcome occurred in 42% in the labetalol group and 44% in the nifedipine group, with an adjusted RR of 1.03 (95% CI: 0.96-1.11) and an adjusted RD of 1.35 per 100 births (95% CI: -1.76 to 4.45).

Where the research disagrees

Whether beta-blockade is a good first choice for hypertension

• The Cochrane review of beta-blockers for hypertension, 2017, systematic-review: Current evidence suggests that initiating treatment of hypertension with beta-blockers leads to modest CVD reductions and little or no effects on mortality. These beta-blocker effects are inferior to those of other antihypertensive drugs. (Source 23)
• The Cochrane review of antihypertensive drugs in pregnancy, 2018, where beta-blockers came out ahead of methyldopa, systematic-review: If antihypertensive drugs are used, beta blockers and calcium channel blockers appear to be more effective than the alternatives for preventing severe hypertension. (Source 24)

How big a liver risk labetalol carries

• Hendriksen and colleagues, 2026, from 27 published cases and FDA reporting data, case-series: The available evidence is consistent with a clinically meaningful and biologically plausible association between labetalol and idiosyncratic hepatotoxicity, supporting heightened clinical awareness and further mechanistic and population-based study. (Source 16)
• The labetalol label itself, which calls severe hepatocellular injury rare and usually reversible, position: The hepatic injury is usually reversible, but hepatic necrosis and death have been reported. Injury has occurred after both short- and long-term treatment and may be slowly progressive despite minimal symptomatology. (Source 13)

Whether labetalol can ever be used in someone with asthma or another bronchospastic airway disease - the same label says both things

• The label's CONTRAINDICATIONS section (labetalol tablets, effective 2026-03-05), position: Labetalol hydrochloride is contraindicated in bronchial asthma, overt cardiac failure, greater-than-first-degree heart block, cardiogenic shock, severe bradycardia, other conditions associated with severe and prolonged hypotension, and in patients with a history of hypersensitivity to any component of the product (see WARNINGS ). Beta-blockers, even those with apparent cardioselectivity, should not be used in patients with a history of obstructive airway disease, including asthma. (Source 19)
• The Nonallergic Bronchospasm paragraph that the same label prints inside its WARNINGS subsection on abrupt withdrawal, position: Patients with bronchospastic disease should, in general, not receive beta-blockers. Labetalol hydrochloride may be used with caution, however, in patients who do not respond to, or cannot tolerate, other antihypertensive agents. It is prudent, if labetalol hydrochloride is used, to use the smallest effective dose, so that inhibition of endogenous or exogenous beta-agonists is minimized. (Source 25)

How much

• Reference intake: There is no reference intake for a prescription antihypertensive; the dose is set by the prescriber and titrated to blood pressure. As a position, the tablet label with an effective date of 2026-03-05 opens by stating that dosage must be individualised, records a recommended initial dosage of 100 mg twice daily and a usual maintenance dosage between 200 mg and 400 mg twice daily. (Source 26)
• Upper limit: The tablet label's stated ceiling, as a position dated 2026-03-05, is that patients with severe hypertension may require 1,200 mg to 2,400 mg per day, with titration increments not exceeding 200 mg twice daily. The same section treats that ceiling as a tolerability trade-off rather than a neutral number: it records that should side effects, principally nausea or dizziness, occur with these doses given twice daily, the same total daily dose given three times daily may improve tolerability and facilitate further titration. The dose-by-dose rise in dizziness and nausea is printed in the label's ADVERSE REACTIONS section, not here, and is carried by the harm finding that quotes that section. (Source 26)
• Studied: The Easterling trial randomised women to 200 mg oral labetalol hourly with escalation if hypertension was maintained, against 10 mg oral nifedipine with escalation or a single 1000 mg dose of methyldopa without escalation. (Source 27)
• Studied: The label's dose-ranging adverse-event table covers daily doses from 200 mg to 2,400 mg and is introduced as the table that depicts the entire U.S. therapeutic trials data base for adverse reactions that are clearly or possibly dose related. The label prints a separate patient count for each dose column and no overall total: 522 at 200 mg; 181 at 300 mg; 606 at 400 mg; 608 at 600 mg; 503 at 800 mg; 117 at 900 mg; 411 at 1,200 mg; 242 at 1,600 mg; 175 at 2,400 mg. Those column counts must not be added together into a number of people studied - a dose-titration database can count the same patient in more than one dose column, and the label states no total anywhere in the section. (Source 14)

A common belief, and what the research shows

The belief: Labetalol is safe in pregnancy, so it must be safe for the baby too.

What the research shows: The pregnancy evidence is about the mother's blood pressure and the pregnancy outcome, and it is genuinely favourable: in CHAP, treating mild chronic hypertension cut the primary composite outcome from 37.0% to 30.2% with no increase in small-for-gestational-age births. But the newborn is separately affected. A meta-analysis of 55 studies of beta-blocker exposure found a probable risk of hypoglycemia (CoE-Moderate) and possible risk of bradycardia (CoE-Low) in neonates upon fetal beta-blocker exposure. Therefore, we suggest the monitoring of glucose levels in exposed neonates until 24 h after birth. Due to the limited clinical implication, monitoring of the heart rate could be considered for 24 h. We call for future studies to substantiate our findings. The label records the same thing: Hypotension, bradycardia, hypoglycemia, and respiratory depression have been reported in infants of mothers who were treated with labetalol hydrochloride for hypertension during pregnancy.

Questions and answers

What is it?

Labetalol is a prescription blood-pressure drug that blocks both alpha-1 and beta adrenaline receptors. It is taken as a tablet for ongoing high blood pressure and given by vein for severe high blood pressure. Blocking alpha-1 relaxes blood vessels; blocking beta stops the heart compensating by speeding up. (Source 1)

What does it do in the body?

It lowers blood pressure without the reflex rise in heart rate that pure vessel-relaxing drugs cause, because it blocks that reflex at the same time. The label records dose-related falls in blood pressure, small non-significant changes in cardiac output, small falls in total peripheral resistance, and reduced plasma renin. Because the alpha-blockade matters more when upright, the fall is larger standing than lying down. One figure to treat carefully: this section gives symptoms of postural hypotension as 2%, while the label's own adverse-reactions table gives postural hypotension as 1% in the same trials, and the label never reconciles the two. (Source 1)

Is it good or bad for you?

It depends heavily on who is taking it. In pregnancy the evidence is good: treating mild chronic hypertension improved pregnancy outcomes in a 2,408-woman randomised trial. For ordinary adult hypertension, a Cochrane review of beta-blockers as first-line therapy found no mortality benefit against placebo and worse cardiovascular outcomes than calcium-channel blockers, though most participants took atenolol rather than labetalol. In asthma it is contraindicated, and it can mask low blood sugar in diabetes. (Source 23)

How do you get more of it?

There is no food, supplement or behaviour that provides labetalol; it is prescription-only. As a position, the tablet label dated 2026-03-05 begins by saying dosage must be individualised, with a recommended initial dosage of 100 mg twice daily and a usual maintenance dosage between 200 mg and 400 mg twice daily. That is the label's statement to prescribers, not advice to a reader. One thing that changes how much reaches the blood is food, which increases the absolute bioavailability. (Source 26)

If it is harmful, what reduces it?

The drug clears on its own with a plasma half-life of about 6 to 8 hours after an oral dose, mainly as glucuronide metabolites in urine and bile; dialysis removes less than 1%. But getting rid of it deliberately is not simply a matter of stopping: the label directs that in people with ischaemic heart disease the dose be reduced gradually over 1 to 2 weeks, because abrupt beta-blocker withdrawal has been followed by worsening angina and in some cases myocardial infarction. The exception is liver injury, where the label says stop and do not restart. (Source 10)

Why might someone be low in it or missing it?

Nobody is naturally low in labetalol. The reasons someone is not given it are the label's contraindications: bronchial asthma, overt cardiac failure, heart block beyond first degree, cardiogenic shock, severe bradycardia, other conditions associated with severe and prolonged hypotension, and hypersensitivity to a component. It is also stopped if there is laboratory evidence of liver injury or jaundice. One qualification on the asthma entry: the same label is not consistent about it. CONTRAINDICATIONS makes bronchial asthma an absolute bar, while a paragraph inside WARNINGS says labetalol 'may be used with caution, however, in patients who do not respond to, or cannot tolerate, other antihypertensive agents', at the smallest effective dose. The label never reconciles the two, so for someone with airway disease this is a prescriber's judgement rather than something the label settles. (Source 19)

Which whole foods contain it or feed it?

No whole food contains labetalol. Food is relevant the other way round: taking the tablet with food increases the proportion of the dose that reaches the bloodstream, because less is destroyed on the first pass through the liver. That means the same tablet can deliver more drug with a meal than without one. (Source 8)

What happens if you do not have it?

Not taking labetalol is not a deficiency; the question is what happens to untreated high blood pressure. The most specific randomised evidence is in pregnancy: in CHAP, reserving treatment for severe hypertension rather than treating to a target below 140/90 mm Hg left 37.0% of women with a primary-outcome event against 30.2% treated, and any preeclampsia occurred in 31.1% against 24.4%. (Source 28)

How can you test for it?

Blood levels of labetalol are not measured in ordinary care. What is monitored is the person: standing blood pressure, which the label uses as the indicator for titration, and periodic liver tests, which the label says would be appropriate for anyone taking it and should be done at the first sign of liver dysfunction. One test caution matters: labetalol metabolites in urine can produce falsely high catecholamine and metanephrine results and a false-positive urine amphetamine screen on some assays. (Source 13)

References

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2. The Cochrane database of systematic reviews. Beta-blockers for hypertension.. 2017. PMID 28107561, DOI 10.1002/14651858.CD002003.pub5. Read the source
3. Lancet (London, England). Oral antihypertensive regimens (nifedipine retard, labetalol, and methyldopa) for management of severe hypertension in pregnancy: an open-label, randomised controlled trial.. 2019. PMID 31378394, DOI 10.1016/S0140-6736(19)31282-6. Read the source
4. The New England journal of medicine. Treatment for Mild Chronic Hypertension during Pregnancy.. 2022. PMID 35363951, DOI 10.1056/NEJMoa2201295. Read the source
5. DailyMed (U.S. National Library of Medicine), SPL setid bf84ebae-3c91-4448-b1db-8e5ed3053866. Labetalol Hydrochloride Tablets, USP (Avet Pharmaceuticals Inc.) - DailyMed Structured Product Label, section: Pheochromocytoma. 2026. Read the source
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9. DailyMed (U.S. National Library of Medicine), SPL setid bf84ebae-3c91-4448-b1db-8e5ed3053866. Labetalol Hydrochloride Tablets, USP (Avet Pharmaceuticals Inc.) - DailyMed Structured Product Label, section: Drug Interactions, including its nested subsection Risk of Anaphylactic Reaction. 2026. Read the source
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14. DailyMed (U.S. National Library of Medicine), SPL setid bf84ebae-3c91-4448-b1db-8e5ed3053866. Labetalol Hydrochloride Tablets, USP (Avet Pharmaceuticals Inc.) - DailyMed Structured Product Label, section: ADVERSE REACTIONS. 2026. Read the source
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17. International journal of environmental research and public health. The Risk for Neonatal Hypoglycemia and Bradycardia after Beta-Blocker Use during Pregnancy or Lactation: A Systematic Review and Meta-Analysis.. 2022. PMID 35954977, DOI 10.3390/ijerph19159616. Read the source
18. DailyMed (U.S. National Library of Medicine), SPL setid bf84ebae-3c91-4448-b1db-8e5ed3053866. Labetalol Hydrochloride Tablets, USP (Avet Pharmaceuticals Inc.) - DailyMed Structured Product Label, section: Nonteratogenic Effects:. 2026. Read the source
19. DailyMed (U.S. National Library of Medicine), SPL setid bf84ebae-3c91-4448-b1db-8e5ed3053866. Labetalol Hydrochloride Tablets, USP (Avet Pharmaceuticals Inc.) - DailyMed Structured Product Label, section: CONTRAINDICATIONS. 2026. Read the source
20. DailyMed (U.S. National Library of Medicine), SPL setid bf84ebae-3c91-4448-b1db-8e5ed3053866. Labetalol Hydrochloride Tablets, USP (Avet Pharmaceuticals Inc.) - DailyMed Structured Product Label, section: Hypoglycemia. 2026. Read the source
21. The Cochrane database of systematic reviews. Antihypertensive drug therapy for mild to moderate hypertension during pregnancy.. 2018. PMID 30277556, DOI 10.1002/14651858.CD002252.pub4. Read the source
22. JACC. Advances. Comparative Effectiveness and Safety of Labetalol Versus Nifedipine for Treatment of Chronic Hypertension During Pregnancy.. 2025. PMID 40772922, DOI 10.1016/j.jacadv.2025.102054. Read the source
23. The Cochrane database of systematic reviews. Beta-blockers for hypertension.. 2017. PMID 28107561, DOI 10.1002/14651858.CD002003.pub5. Read the source
24. The Cochrane database of systematic reviews. Antihypertensive drug therapy for mild to moderate hypertension during pregnancy.. 2018. PMID 30277556, DOI 10.1002/14651858.CD002252.pub4. Read the source
25. DailyMed (U.S. National Library of Medicine), SPL setid bf84ebae-3c91-4448-b1db-8e5ed3053866. Labetalol Hydrochloride Tablets, USP (Avet Pharmaceuticals Inc.) - DailyMed Structured Product Label, Nonallergic Bronchospasm paragraph, printed by the label inside the WARNINGS subsection "Exacerbation of Ischemic Heart Disease Following Abrupt Withdrawal". 2026. Read the source
26. DailyMed (U.S. National Library of Medicine), SPL setid bf84ebae-3c91-4448-b1db-8e5ed3053866. Labetalol Hydrochloride Tablets, USP (Avet Pharmaceuticals Inc.) - DailyMed Structured Product Label, section: DOSAGE AND ADMINISTRATION. 2026. Read the source
27. Lancet (London, England). Oral antihypertensive regimens (nifedipine retard, labetalol, and methyldopa) for management of severe hypertension in pregnancy: an open-label, randomised controlled trial.. 2019. PMID 31378394, DOI 10.1016/S0140-6736(19)31282-6. Read the source
28. The New England journal of medicine. Treatment for Mild Chronic Hypertension during Pregnancy.. 2022. PMID 35363951, DOI 10.1056/NEJMoa2201295. Read the source