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Written by Stephanie Nera, RPh, PharmD · Pharmacology

Updated Sep 08, 2020


Labetalol is part of a class of drugs known as antihypertensives, specifically a beta-blocker. Beta-blockers work by binding to the β-adrenergic receptors found on the heart and blood vessels. This causes the heart to beat slower and reduces systemic blood pressure.

Unlike most other beta-blockers, labetalol also binds to α1-adrenergic receptors which have a more selective action on blood vessels, leading to a greater reduction in blood pressure. Because labetalol is a non-selective beta-blocker, it also binds to the β-adrenergic receptors found in the lungs which may cause symptoms such as cough.

Labetalol is mainly indicated to treat the following conditions:

  • Hypertension
  • Hypertension in pregnancy
  • Emergency treatment of hypertension
  • Hypotensive anesthesia

How should I take labetalol?

Labetalol is available as an oral tablet and solution for injection in vials. The oral tablet should be taken by mouth without chewing or crushing it. The IV solution should be administered by a licensed health professional in a clinical setting.

How do I store labetalol?

This drug should be stored at room temperature (<30°C) and be protected from light and moisture. Always check the label before using this product. For safety, keep out of the reach of children and pets.

Do not use if the printed expiration date has passed, the product seal has been broken, or the product has changed in color, odor, or consistency.

Do not dispose of this product by pouring it down the drain, toilet, or into the environment. Ask your pharmacist regarding the proper way and location of disposal.

Precautions & Warnings

Beta-blockers, including labetalol, are associated with an increased risk of hypotension and cough. This risk is further increased in older patients usually over 60 years of age, regular alcohol drinkers, and those with respiratory conditions.

Some groups of people with conditions like asthma may experience an exacerbation of symptoms after using beta-blockers.

Before using this medication, inform your doctor if:

  • You have ever had an allergic reaction to labetalol or other beta-blockers
  • You have a history of allergy to other medications, food, or other substances
  • You are taking other medications, especially other antihypertensives
  • You have underlying health conditions

Is it safe during pregnancy or breastfeeding?

This drug is a pregnancy category C drug. There is insufficient evidence from human studies that shows it can cause fetal harm when taken during pregnancy. Labetalol is considered an effective agent for the treatment of acute hypertension and thyrotoxicosis during labor.

This drug should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus, as determined by your doctor.

This drug may be excreted in breast milk. This drug should be used while breastfeeding only if the potential benefit justifies the potential risk to the child, as determined by your doctor.

Side Effects

All drugs have the potential to elicit side effects even with normal use. Many side effects are dose-related and will resolve when it is adjusted or at the end of therapy.

Potential side effects while using this drug include:

  • Intraoperative floppy iris syndrome
  • Orthostatic hypotension (drop in blood pressure after standing)
  • Bradycardia (slow heart rate)
  • Syncope (fainting)
  • Paresthesia (“pins and needles” feeling)
  • Dizziness
  • Dyspnea
  • Fatigue
  • Vertigo
  • Headache
  • Stuffy nose
  • Nausea, vomiting, diarrhea
  • Abdominal pain
  • Male impotence
  • Constipation, flatulence
  • Change in sense of taste
  • Tremor
  • Muscle weakness
  • Nightmares
  • Claudication
  • Rash

Seek medical attention immediately if you experience any of these serious, potentially fatal drug reactions:

  • Hepatic injury
  • Jaundice

You may experience some, none, or other side effects not mentioned above. If you have any concerns about a side effect or it becomes bothersome, consult your doctor or pharmacist.


This drug may interact with other medications. To avoid any potential drug interactions, you should keep a list of all the drugs you are using (including prescription drugs, nonprescription drugs, and herbal products) and inform your doctor and pharmacist.

Known drugs and their interactions with labetalol include:

  • Halothane
    • Increased hypotensive effects
  • Cimetidine
    • Increased bioavailability of labetalol
  • Glutethimide
    • Decreased bioavailability of labetalol
  • Nitroglycerin
  • Increased risk of hypotension
  • Tricyclic antidepressants
    • Increased risk of tremors
  • Calcium channel blockers
    • Increased risk of bradycardia and heart block
  • Sodium bicarbonate 5% and alkaline solutions
    • Incompatible
  • If you experience an adverse drug interaction, stop taking this drug and continue taking your other medication. Inform your doctor immediately to reevaluate your treatment plan. Your dose may need to be adjusted, substituted with another drug, or discontinue using the drug.

    Does food or alcohol interact with labetalol?

    There are no notable interactions with food. Labetalol is best taken with meals. This drug should not be taken with alcohol as it may increase the severity of hypotension.

    Inform your doctor or pharmacist if you have any concerns regarding food-drug interactions.

    What health conditions may interact with labetalol?

    This drug should be taken with caution if you have any of the following conditions or risk factors:

    • Active bronchial asthma
    • 2nd or 3rd-degree heart block
    • Cardiogenic shock
    • Prolonged or severe hypotension
    • Uncompensated heart failure
    • Severe bradycardia
    • Pheochromocytoma
    • Diabetes mellitus
    • Candidate for surgery with general anesthesia
    • Hepatic impairment

    Inform your doctor or pharmacist if you have any concerns regarding specific health conditions.


    The information provided is not a substitute for any medical advice. You should ALWAYS consult your doctor or pharmacist before using labetalol.

    What is the dose of labetalol for an adult?

    For hypertension

    • Initial dose: Take 100 mg 2 times a day. Increased to 200 to 400 mg 2 times a day, depending on the response.
      • Dose adjustment for elderly patients: Start with 50 to 100 mg 2 times a day. Maintenance: 100 to 200 mg 2 times a day.
  • Maximum dose: 2.4 g per day in 2 to 4 divided doses.
  • For hypertension in pregnancy

    • Start at an infusion rate of 20 mg/hour, doubling the rate every 30 minutes until the desired response is achieved.
    • Maximum infusion rate: 160 mg/hour

    For emergency treatment of hypertension

    • Administer 20 mg via slow IV injection for at least 2 minutes, followed by 40 to 80 mg dose every 10 minutes, going up to 300 mg if necessary.
    • Note: The patient should remain supine during and 3 hours after the procedure.

    For hypotensive anesthesia

    • Administer 10 to 20 mg then increase at 5 to 10 mg increments if the desired degree of hypotension is not achieved after 5 minutes. Administer higher initial doses if halothane anesthesia is not used.

    What is the dose of labetalol for a child?

    This drug is not recommended for use in children and the recommended dose has not been established. Consult a doctor or pharmacist for alternatives and more information.

    How is labetalol available?

    This drug is available in the following brands, dosage forms, and strengths:

    • Abetol oral tablets 100 mg, 200 mg, 300 mg
    • Entraver solution for injection 5 mg/mL

    What should I do in case of an emergency or overdose?

    In case of an emergency or an overdose, call your local emergency services or go to your nearest emergency room.

    What should I do if I miss a dose?

    If you miss a dose of this drug, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and take your regular dose as scheduled. Do not take a double dose.


    Hello Health Group does not provide medical advice, diagnosis or treatment.

    Written by

    Stephanie Nera, RPh, PharmD


    Updated Sep 08, 2020

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