Metoprolol belongs to a group of medicines called beta blockers.

It's used to:

• treat high blood pressure
• treat illnesses that cause an irregular heartbeat
• prevent future heart disease, heart attacks and strokes
• prevent chest pain caused by angina
• prevent migraines

Metoprolol can help reduce your symptoms if you have too much thyroid hormone in your body (thyrotoxicosis).

You'll usually take it together with medicines to treat an overactive thyroid.

This medicine comes as tablets and is only available on prescription. It's also given by injection, but this is usually done in hospital.

• Metoprolol slows down your heart rate and makes it easier for your heart to pump blood around your body.
• Your very first dose of metoprolol may make you feel dizzy, so take it at bedtime. If you don't feel dizzy after that, you can take it in the morning.
• Metoprolol is usually taken once or twice a day, but sometimes it's prescribed to be taken up to 4 times a day.
• The main side effects of metoprolol are headaches, and feeling dizzy, sick or tired - these are usually mild and short-lived.
• Metoprolol also goes by the brand name Lopresor. When given by injection, it may be called by the brand name Betaloc.

Metoprolol can be taken by adults over the age of 18.

It isn't suitable for everyone. To make sure it's safe for you, tell your doctor before starting metoprolol if you have:

• had an allergic reaction to metoprolol or any other medicine in the past
• low blood pressure or a slow heart rate
• a lung disease or severe asthma
• metabolic acidosis - when there's too much acid in your blood
• an overactive thyroid (hyperthyroidism) - metoprolol may make it more difficult to recognise the warning signs of having too much thyroid hormone in your body (thyrotoxicosis)
• severe blood circulation problems in your limbs (such as Raynaud's phenomenon), which may make your fingers and toes tingle or turn pale or blue
• a liver problem

Metoprolol comes as 2 different types of tablet: standard release and slow release.

Slow release is also called sustained release (SR):

• standard release - releases metoprolol into your body quickly (you may need to take it several times a day depending on your dose)
• slow release - dissolves slowly so you don't have to take it as often (once a day is usually enough)

Your doctor may advise you to take your first dose before bedtime because it could make you feel dizzy.

If you don't feel dizzy after the first dose, take metoprolol in the morning.

If you have metoprolol more than once a day, try to space the doses evenly throughout the day.

How much will I take?

How much you take depends on why you need metoprolol and the type of tablet you're taking.

• For high blood pressure: standard release - 50mg to 100mg twice a day; slow release - 200mg once a day
• For chest pain (angina): standard release - 50mg to 100mg 2 to 3 times a day; slow release - 200mg to 400mg once a day
• For an irregular heartbeat (arrhythmia): standard release - 50mg 2 to 3 times a day
• For preventing migraine: standard release - 50mg 2 to 4 times a day, or 100mg twice a day
• For too much thyroid hormone (thyrotoxicosis): standard release - 50mg 4 times a day

How to take it

You can take metoprolol with or without food, but it's best to do the same each day.

Swallow the tablets whole with a drink of water.

Some brands have a score line to help you break the tablet in half and make it easier to swallow.

Check the information leaflet for your brand to see if you can do this.

What if I forget to take it?

If you miss a dose, take your metoprolol as soon as you remember, unless it's nearly time for your next dose.

In this case, just leave out the missed dose and take your next dose as normal.

Never take 2 doses at the same time. Never take an extra dose to make up for a forgotten one.

If you often forget doses, it may help to set an alarm to remind you.

You could also ask your pharmacist for advice on other ways to help you remember to take your medicine.

What if I take too much?

Taking too much metoprolol can slow down your heart rate and make it difficult to breathe. It can also cause dizziness and trembling.

The amount of metoprolol that can lead to an overdose varies from person to person.

Like all medicines, metoprolol can cause side effects, but many people have no side effects or only minor ones.

Side effects often improve as your body gets used to the medicine.

Common side effects

These common side effects happen in more than 1 in 100 people. They're usually mild and short-lived.

Talk to your doctor or pharmacist if the side effects bother you or last more than a few days:

• headaches
• feeling tired, dizzy or weak
• cold hands or feet
• feeling sick (nausea)
• stomach ache

Serious side effects

It's rare, but some people have serious side effects when taking metoprolol.

Call a doctor straight away if you have:

• shortness of breath, wheezing and tightening of the chest - these can be signs of lung problems
• shortness of breath with a cough that gets worse when you exercise (like walking up stairs), swollen ankles or legs, chest pain, an irregular heartbeat - these are signs of heart problems
• a fast heart rate, high temperature (38C and above), trembling and confusion - these are signs of too much thyroid hormone in the blood (thyrotoxicosis)
• yellow skin or the whites of your eyes turn yellow - these can be signs of liver problems

Serious allergic reaction

In rare cases, metoprolol may cause a serious allergic reaction (anaphylaxis).

These aren't all the side effects of metoprolol.

For a full list, see the leaflet inside your medicine packet.

What to do about:

• headaches - make sure you rest and drink plenty of fluids. Do not drink too much alcohol. Ask your pharmacist to recommend a painkiller. Headaches usually go away after the first week of taking metoprolol. Talk to your doctor if the headaches are severe or last longer than a week.
• feeling tired, dizzy or weak - if metoprolol makes you feel dizzy or weak, stop what you're doing, and sit or lie down until you feel better. Do not drive or use tools or machinery if you're feeling tired. Do not drink alcohol - it'll make you feel worse.
• cold hands or feet - put your hands or feet under warm running water, massage them, and wiggle your fingers and toes. Do not smoke or have drinks with caffeine in - these can make your blood vessels narrower and restrict your blood flow. Smoking also makes your skin colder. Try wearing mittens (they're warmer than gloves) and warm socks. Do not wear tight watches or bracelets.
• feeling sick (nausea) - stick to simple meals and avoid rich or spicy food. It might help to take your metoprolol after you have eaten.
• stomach pain - try to rest and relax. It can help to eat and drink slowly and have smaller and more frequent meals. Putting a heat pad or covered hot water bottle on your stomach may also help. If you're in a lot of pain, speak to your pharmacist or doctor.

Metoprolol isn't usually recommended in pregnancy.

If you're trying to get pregnant or are already pregnant, talk to your doctor about the benefits and possible harms of taking metoprolol.

Your doctor may recommend another medicine, such as labetalol. It's similar to metoprolol and is often prescribed for high blood pressure in pregnancy.

Metoprolol and breastfeeding

It's usually safe to take metoprolol if you're breastfeeding.

This is because only a small amount gets into breast milk, and it's not enough to cause any problems to your baby.

But speak to your doctor before taking metoprolol if your baby is premature or has kidney problems.

There are some medicines that may interfere with the way metoprolol works.

Tell your doctor if you're taking:

• other medicines for high blood pressure - the combination with metoprolol can sometimes lower your blood pressure too much, which may make you feel dizzy or faint; tell your doctor if this keeps happening as they may change your dose
• other medicines that can lower your blood pressure - these include some antidepressants, nitrates (for chest pain), baclofen (a muscle relaxant), tamsulosin (for an enlarged prostate), and co-careldopa and levodopa (for Parkinson's disease)
• non-steroidal anti-inflammatory medicines (NSAIDs), such as ibuprofen - these medicines may increase your blood pressure, so it's best to keep them to a minimum
• cough medicines that contain pseudoephedrine or xylometazoline
• medicines for diabetes - metoprolol may make it more difficult to recognise the warning signs of low blood sugar
• medicines for allergies - such as ephedrine, noradrenaline or adrenaline
• medicines for asthma or chronic obstructive pulmonary disease (COPD)

Mixing metoprolol with herbal remedies or supplements

There's very little information about taking herbal remedies and supplements with metoprolol.