Labetalol

Key facts

• Labetalol (the active ingredient in Trandate) is an alpha- and beta-blocker. It relaxes blood vessels and slows the heart's response to adrenaline, lowering blood pressure.
• Tablets are usually taken twice daily. In hospital, an injection can bring severe blood pressure spikes down quickly.
• Never stop labetalol suddenly. Abrupt withdrawal can cause a rebound rise in blood pressure, chest pain, or a heart attack, especially if you have underlying heart disease.
• Seek urgent care for a very slow or irregular heartbeat, fainting, or sudden severe shortness of breath.

What labetalol treats

Labetalol treats hypertension, including situations where blood pressure needs to come down quickly. It is also used for high blood pressure that develops during pregnancy (pre-eclampsia), where it is one of the medicines considered appropriate, and to keep blood pressure steady around surgery.

How labetalol works

Labetalol blocks both alpha and beta receptors, the signals that normally tighten blood vessels and speed up the heart. Blocking them relaxes the vessel walls and reduces how hard the heart has to pump, so blood pressure falls.

Before you take it

• Avoid labetalol if you have severe asthma or bronchospasm, a very slow heart rate, certain types of heart block, or uncontrolled heart failure.
• Tell your prescriber about liver disease, diabetes (labetalol can mask warning signs of low blood sugar), and any other blood-pressure or heart-rhythm medicines you take.
• Alcohol increases the blood-pressure-lowering effect and can worsen dizziness or fainting.
• Combining labetalol with verapamil or diltiazem can slow the heart too much; this pairing needs close monitoring.

Side effects

Common effects include dizziness on standing, tiredness, cold hands or feet, mild nausea, and scalp tingling in the first days of treatment.

Stop and seek urgent medical care for any of these:

• A very slow, irregular, or pounding heartbeat, or fainting.
• Severe wheezing or worsening shortness of breath.
• Marked swelling of the legs or ankles, suggesting fluid buildup.
• Yellowing of the skin or eyes, dark urine, or persistent nausea, rare signs of liver injury.

Safety essentials

• Do not stop labetalol abruptly. Your prescriber will taper the dose gradually, even when switching to another blood pressure medicine.
• Avoid it if you have severe asthma, marked bradycardia, or specific types of heart block; these can turn dangerous once the heart's response is blocked.
• Rare but serious liver injury has been reported. Get blood tests if you develop nausea, fatigue, or jaundice while taking it.
• Check your blood pressure and pulse as directed, particularly after a dose change.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.