Watch: What are beta blockers and what do they do in your body?
Beta blockers are among the most important drugs used by cardiologists. Adam Timmis, Professor of Clinical Cardiology in the National Institute for Health Research Biomedical Research Unit, answers some common questions.
What exactly are beta blockers?
They are inexpensive, well tolerated drugs and save many lives by lowering blood pressure, protecting against recurrent heart attacks and helping people with heart failure to live longer.
They are used to treat conditions including angina, heart failure and some heart rhythm disorders, and after a heart attack.
They are also sometimes prescribed for glaucoma, anxiety and migraines.
Common beta blockers include:
- atenolol (brand names include Tenormin)
- bisoprolol (brand names include Cardicor, Emcor)
- metoprolol (brand names include Betaloc, Lopresor)
- nebivolol (brand names include Nebilet)
- propranolol (brand names include Inderal)
How do they work?
Beta blockers, also called beta adrenergic blocking agents, block the release of the stress hormones adrenaline and noradrenaline in certain parts of the body. This results in a slowing of the heart rate and reduces the force at which blood is pumped around your body.
Beta blockers can also block your kidneys from producing a hormone called angiotensin II. This results in lowering your blood pressure.
Why would I be prescribed this?
By slowing the heart rate, beta blockers reduce the oxygen demand of the heart and reduce the frequency of angina attacks
Beta blockers are widely prescribed for people with heart disease in these ways:
Treatment of angina
By slowing the heart rate, beta blockers reduce the oxygen demand of the heart and reduce the frequency of angina attacks. Guidelines recommend beta blockers as first-line treatment in patients with angina either on their own or in combination with a calcium channel blocker.
Treatment of heart failure
Beta blockers improve life expectancy in people with heart failure caused by impaired contraction of the left ventricle (the main pump chamber of the heart). Guidelines recommend that all patients with left ventricular impairment should take a beta blocker – regardless of symptom severity – as part of a treatment plan that also includes angiotensin converting enzyme (ACE) inhibitors, for example ramipril, and, in many cases, an aldosterone inhibitor.
Read more about ACE inhibitors
Treatment of some heart rhythm disorders
Beta blockers are used to control the irregular heart rhythm in people with atrial fibrillation (AF). By slowing the heart rate, the symptoms caused by AF, particularly palpitations and fatigue, are often improved.
Read Mike's story of living with atrial fibrillation
Protection against recurrent heart attacks
In people who have had a heart attack, beta blockers help reduce the risk of further ones. Guidelines recommend that all patients who have had a heart attack should be prescribed a beta blocker before hospital discharge as part of a package of risk reduction measures. Treatment should usually continue for life.
Read more about heart attacks
Control of blood pressure
Beta blockers are commonly used to help lower blood pressure, usually as a part of a treatment plan that may include an ACE inhibitor (for example, ramipril) and/or a calcium channel blocker (for example, amlodipine).
Read more about calcium channel blockers
Adam Timmis's fast facts about beta blockers
- Beta blockers block the release of the stress hormones adrenaline and noradrenaline.
- They are widely prescribed for angina, heart failure and some heart rhythm disorders, and to control blood pressure.
- They are usually tolerated well without significant side effects.
Are there different types?
Beta blockers are classified as being non-selective and selective. Non-selective beta blockers, such as propranolol, are active in blocking adrenaline and noradrenaline in other areas of the body, as well as the heart.
This can cause some unwanted side effects, including cold hands and a predisposition to asthma attacks.
Selective beta blockers, such as atenolol and bisoprolol, are used more commonly by cardiologists because their activity mostly affects the heart and has less pronounced effects in other parts of the body.
Is there anybody who shouldn’t be prescribed a beta blocker?
There are some conditions in which beta blockers are not recommended. This includes uncontrolled heart failure, hypotension (low blood pressure), certain problems with the rhythm of your heart, or bradycardia (a very slow heart beat). If you have been diagnosed with asthma or another lung disease, beta blockers are not normally prescribed because they can occasionally provoke severe asthma attacks. Your doctor will consider the balance of benefits versus risks.
What are the potential side effects?
Beta blockers are usually tolerated well without significant side effects
Beta blockers are usually tolerated well without significant side effects. They may cause cold hands and feet, particularly in older people, and may also be associated with unusually vivid dreams. Some patients experience fatigue, perhaps related to excessive slowing of the heart rate. Erectile dysfunction is occasionally a problem for some men who take beta blockers.
If you think you are experiencing side effects, speak to your GP as soon as possible.
Do not stop taking a beta blocker suddenly without consulting your doctor. This is important because when you take a beta blocker regularly, your body becomes used to it. Stopping it suddenly could cause problems such as palpitations, a recurrence of angina pain or a rise in blood pressure.
If I experience severe side effects, is there something else I can take?
Side effects can often be managed by reducing the dose or switching to a selective beta blocker. However, if you have problems with beta blockers, there are alternative drugs available. If you have angina or AF, for example, other drugs that slow the heart rate, such as diltiazem or verapamil, may be substituted. The recently available ivabradine also slows the heart rate and can be used to treat angina (but not AF) if beta blockers aren’t advised.