Labetalol (also called labetalol hydrochloride) is a prescription medicine used to treat high blood pressure (hypertension). Doctors often use it for high blood pressure during pregnancy, including pre-eclampsia, a pregnancy condition with high blood pressure. In hospitals, an injection form is used to bring very high blood pressure down quickly. Labetalol contains one active ingredient, labetalol hydrochloride. It comes as film-coated tablets in several strengths, and as an injection for hospital use only. It blocks two kinds of receptors, alpha and beta, which are signal points in the body. This relaxes blood vessels and stops the heart from beating faster than it needs to. Lowering blood pressure this way reduces strain on the heart, kidneys, brain and blood vessels over time.

Labetalol lowers blood pressure in two ways at once. Most medicines in the beta-blocker family only slow the heart and reduce how hard it pumps. Labetalol also blocks alpha-1 receptors in the walls of blood vessels. This lets the vessels widen, so blood flows with less pressure. Because both actions happen together, blood pressure falls without the strong, fast heartbeat the body sometimes uses to make up for widened vessels.

Doctors prescribe Labetalol tablets for long-term control of high blood pressure. They may be used alone or with other blood pressure medicines, such as water tablets (diuretics). The medicine is widely used for high blood pressure in pregnancy because doctors have long experience with it in pregnant women. In hospital, Labetalol injection is given slowly into a vein for severe high blood pressure that needs fast control. Only trained staff give it, with close monitoring.

The tablet is taken by mouth, usually twice a day. Food increases how much of the medicine the body absorbs. Taking it with meals in the same way each day keeps its effect steady. The full blood pressure effect of a new dose can take a day to a few days to appear.

Labetalol needs medical supervision. The most common problem is dizziness or light-headedness when standing up, especially in the first weeks or after a dose increase. Rarely, the medicine can cause serious liver injury. Report unusual tiredness, dark urine or yellowing of the skin straight away.

Labetalol must not be used by people with any of these:

• asthma
• heart failure that is not under control
• a very slow heartbeat
• serious heart block (a problem with the heart's electrical signals)
• cardiogenic shock (when the heart cannot pump enough blood)
• very low blood pressure
• a known allergy to labetalol

It is generally avoided in other lung conditions that narrow the airways, such as chronic bronchitis or emphysema.

It should not be stopped suddenly. Stopping a beta-blocker all at once can make chest pain worse in people with heart disease. If it needs to be stopped, your doctor will lower the dose slowly over a week or two.

1. Two actions in one medicine - Labetalol widens blood vessels and calms the heart at the same time. Blood pressure comes down without a fast, pounding heartbeat.
2. Widely used in pregnancy - It is one of the main medicines doctors use for high blood pressure in pregnancy and pre-eclampsia, helping protect both mother and baby.
3. Fast control in emergencies - The injection form lets hospital teams bring dangerously high blood pressure down in a controlled way.
4. Long-term protection - Keeping blood pressure under control lowers the long-term risk of stroke, heart attack, heart failure and kidney damage.
5. Works well with other medicines - It can be combined with other blood pressure medicines, such as diuretics, when one medicine alone is not enough.

Common Side Effects (Usually Mild and may lessen with continued use)

• Dizziness or light-headedness, especially when standing up
• Tiredness or weakness
• Feeling sick (nausea) or indigestion
• Headache
• Stuffy nose
• A tingling or prickling feeling on the scalp or skin, usually early in treatment
• Trouble with ejaculation or erection
• Swelling of the ankles
• Mild skin rash

Serious Side Effects (Seek Urgent Medical Attention)

• Orthostatic (postural) hypotension: a sudden drop in blood pressure when you stand up. It can cause severe dizziness, blurred vision or fainting. It is most likely in the first weeks, after a dose increase, or in hot weather.
• Liver injury: rarely, Labetalol can cause serious liver damage. Warning signs include unusual tiredness, loss of appetite, itching, pain in the upper right side of the belly, dark urine, or yellowing of the skin or eyes (jaundice).
• Bronchospasm: sudden tightening of the airways, causing wheezing or shortness of breath. It is more likely in people with asthma or long-term lung disease.
• Very slow heartbeat (bradycardia) or heart block: heart block means the heart's electrical signals are delayed or stopped. Signs include a very slow pulse, fainting or extreme tiredness.
• Worsening heart failure: breathlessness, needing more pillows to sleep, or quick weight gain from fluid build-up.
• Severe allergic reaction: swelling of the face, lips, tongue or throat, trouble breathing, or a widespread rash.
• Lupus-like reaction: rarely, the immune system reacts to the medicine, causing joint pain, rash and fever.
• Difficulty urinating, especially in older men.

• Take Labetalol exactly as your doctor has prescribed. It is usually taken twice a day, roughly 12 hours apart.
• Take it with food, at the same meals each day. Food increases how much medicine your body absorbs, so taking it the same way every day keeps the effect even.
• Swallow the tablet with a glass of plain water. Do not crush, chew or break the tablet unless your doctor or pharmacist says your tablet can be split.
• Take your doses at the same times every day. Linking them to breakfast and dinner helps you remember.
• Stand up slowly from lying or sitting, especially after the first few doses. Sit or lie down if you feel faint.
• Keep taking Labetalol even when you feel well. High blood pressure often causes no symptoms, and the medicine only works while you keep taking it.
• Do not stop taking it suddenly. If it needs to be stopped, your doctor will lower the dose slowly.
• If you are having cataract surgery or any other operation, tell the surgeon and the anaesthetist that you take Labetalol.

Your body makes natural "stress chemicals", such as adrenaline and noradrenaline. These attach to receptors, which work like locks on cells. Two kinds of receptors matter most for blood pressure:

• Beta receptors on the heart. When stress chemicals attach here, the heart beats faster and pumps harder, which raises blood pressure.
• Alpha-1 receptors on the muscles in blood vessel walls. When stress chemicals attach here, the vessels tighten and narrow, which also raises blood pressure.

Labetalol blocks both. It is a "non-selective" beta-blocker. This means it blocks beta receptors in the heart and also in other places, such as the airways. Blocking them slows the heart and reduces how hard it pumps. At the same time, it blocks alpha-1 receptors, so blood vessels relax and widen.

Taken by mouth, its beta-blocking effect is about three times stronger than its alpha-blocking effect. It also gently stimulates beta-2 receptors in blood vessel walls, which helps the vessels widen a little more.

The two main actions support each other. Usually, when blood vessels widen, the body tries to make up for it by speeding up the heart. Because Labetalol also blocks the heart's beta receptors, it limits that speeding up. Blood pressure falls mainly because blood flows more easily through the vessels, while the amount of blood the heart pumps stays fairly steady. Because it also blocks beta receptors in the airways, Labetalol can tighten the breathing passages in people with asthma.

• Take Labetalol with meals at the same times each day.
• Stand up slowly, especially in the morning and in the first weeks of treatment.
• Check your blood pressure and pulse at home if your doctor advises it. Note the readings for your visits.
• If you have diabetes, check your blood sugar regularly. Labetalol can hide warning signs of low sugar, such as a racing heartbeat and shakiness. Sweating usually still happens.
• Never stop the medicine suddenly. Make sure you do not run out of tablets.
• Report yellowing of the skin or eyes, dark urine or unusual tiredness straight away.
• Tell every doctor, dentist, surgeon and eye surgeon that you take Labetalol.
• If you have a serious allergy, let your doctor know. Beta-blockers can make an adrenaline injection work less well.

• Store below 30°C (86°F), or as directed on the pack. Do not freeze.
• Keep the tablets in the original container, away from direct sunlight, heat and moisture. Do not store them in the bathroom.
• Keep the container tightly closed.
• Keep out of reach and sight of children and pets.
• Do not use tablets after the expiry date. Ask your pharmacist how to get rid of unused medicine safely.

• Food - Taking Labetalol with food increases how much is absorbed. Take it with meals every time so the effect stays even from day to day.
• Alcohol - Alcohol adds to the blood pressure-lowering effect and can cause dizziness or fainting.
• Salt - A diet high in salt can raise blood pressure and work against the medicine. Follow your doctor's advice on salt intake.

• Other blood pressure medicines (diuretics, ACE inhibitors, calcium channel blockers, alpha-blockers) - These add to the effect and may lower blood pressure too much. Doctors often combine them on purpose, with monitoring.
• Verapamil and diltiazem - Together with Labetalol, these can slow the heart too much or weaken its pumping. Close monitoring is needed.
• Tricyclic antidepressants (such as amitriptyline, imipramine) - Shaking (tremor) has been reported when these are taken with Labetalol.
• Cimetidine - This acid-reducing medicine can raise the amount of Labetalol in the blood and increase its effect.
• Nitroglycerin (glyceryl trinitrate) - Using both may lower blood pressure further.
• Asthma reliever inhalers (such as salbutamol) - Labetalol can make these work less well.
• Insulin and diabetes tablets - Labetalol can hide the warning signs of low blood sugar.
• General anaesthetics (such as halothane) - Using these with Labetalol can cause a large fall in blood pressure. Tell your anaesthetist before surgery.
• Adrenaline - People with severe allergies who take beta-blockers may respond less to normal doses of adrenaline during an allergic reaction.

• Asthma - Labetalol must not be used. In other lung conditions that narrow the airways, such as chronic bronchitis and emphysema, it is generally avoided.
• Allergy to labetalol - Do not take it if you have had an allergic reaction to it before.
• Very low blood pressure - It must not be used if your blood pressure is severely low.
• Heart failure - It must not be used in heart failure that is not under control. Even when heart failure is under control, it needs careful monitoring.
• Very slow heartbeat, heart block worse than first-degree, or cardiogenic shock - Heart block is when the heart's electrical signals are delayed or stopped. Cardiogenic shock is when the heart cannot pump enough blood. Labetalol must not be used in these conditions.
• Liver disease - The medicine stays in the body longer, and rarely Labetalol can cause liver injury.
• Diabetes - Signs of low blood sugar may be hidden.
• Overactive thyroid - Labetalol may hide signs such as a fast heartbeat. Stopping it suddenly can make thyroid symptoms worse.
• Pheochromocytoma - This is a rare adrenal gland tumour. Unexpected rises in blood pressure have been reported, so specialist care is needed.
• Cataract surgery - In people taking medicines that block alpha-1 receptors, the iris (the coloured part of the eye) can become floppy during surgery. Tell your eye surgeon.
• Severe allergies - Allergic reactions may be more severe and harder to treat.

• For high blood pressure in adults, treatment usually starts at 100 mg twice a day. The doctor raises the dose step by step based on blood pressure readings.
• The usual maintenance dose is 200 mg to 400 mg twice a day.
• In severe high blood pressure, doctors may prescribe higher totals of 1,200 mg to 2,400 mg a day, split into two or three doses.
• Doses for pregnancy, older adults and people with liver disease are set individually by the doctor.
• The injection is given only in hospital.
• Always take exactly the dose your doctor prescribes. Do not change the dose or stop on your own.

Taking too much Labetalol can cause:

• Severe dizziness or fainting from very low blood pressure, especially on standing
• A very slow heartbeat
• Breathing difficulty or wheezing
• Extreme tiredness, confusion or collapse
• Low blood sugar, mainly in children

What to do: Get emergency medical help straight away or go to the nearest hospital. Take the medicine pack with you. While waiting, the person should lie flat with their legs raised. Do not try to make them vomit. In hospital, doctors can give treatments that raise the heart rate and blood pressure and support breathing.

• Take the missed dose as soon as you remember.
• If it is almost time for your next dose, skip the missed dose and take the next one at the usual time.
• Never take two doses at once to make up for a missed one. This can drop your blood pressure too much.
• If you often forget doses, set a phone alarm or link your doses to meals.

Seek medical help urgently if you have:

• Fainting, or severe dizziness that does not ease when you sit or lie down
• A very slow, irregular or pounding heartbeat
• Wheezing, chest tightness or shortness of breath
• Chest pain, especially after missing doses or stopping the medicine
• Swelling of the feet, quick weight gain or breathlessness when lying down
• Yellow skin or eyes, dark urine, pale stools, itching or pain in the upper right belly
• Swelling of the face, lips or throat, or a severe rash
• Joint pain with rash and fever
• Difficulty passing urine
• During pregnancy: severe headache, blurred vision, pain under the ribs or sudden swelling, which may be signs of worsening pre-eclampsia