What are beta blockers and how do they work?

Dr Roger Henderson
·6 min read
Photo credit: SDI Productions - Getty Images
Photo credit: SDI Productions - Getty Images

Beta blockers are a group of prescription-only medicines used to treat a variety of medical conditions including heart failure, angina, high blood pressure, migraine and some anxiety symptoms. Beta blockers work mainly by slowing down the heart and blocking the action of hormones such as adrenaline.

Dr Roger Henderson looks at what beta blockers are, what they are used for, possible beta blocker side-effects and who should not take them:

What are beta blockers?

Beta blockers are important drugs that are commonly used in a variety of conditions but especially with heart-related problems. They are inexpensive, usually well tolerated, and are regularly prescribed by both heart specialists and GPs. Their full name is ‘beta-adrenoceptor blocking medicines’ but are usually just called beta blockers. There are several types of beta blocker available and the type prescribed for you will depend on your health condition.

How do beta blockers work?

Beta blockers work by blocking the transmission of certain nerves, which in turn blocks the release of stress hormones such as adrenaline and noradrenaline. This causes the heart rate to slow down, and reduces how forcefully the heart pumps blood round the body.

Beta blockers also block the release of another hormone called angiotensin II from the kidneys, which causes the blood pressure to reduce.

Photo credit: Roman Didkivskyi - Getty Images
Photo credit: Roman Didkivskyi - Getty Images

Types of beta blockers

Although beta blockers work the same way, there are a number of different types available including the following:

  • Atenolol (such as Tenormin)

  • Bisoprolol (such as Cardicor)

  • Carvedilol

  • Celiprolol

  • Esmolol

  • Labetalol

  • Metoprolol (such as Betaloc)

  • Nadolol

  • Nebivolol (such as Nebilet)

  • Oxprenolol

  • Pindolol

  • Propranolol (such as Inderal)

  • Sotalol

  • Timolol

Beta blockers can also be classified as selective and non-selective. Selective types (such as atenolol and bisoprolol) have the greatest impact on the heart and so are more commonly used by heart specialists whereas non-selective types (such as propranolol) block the effect of stress hormones in other parts of the body, but which may cause more side effects as a result.

Beta blocker uses

Heart conditions are the most common reason for beta blockers to be prescribed, and they are often used to treat the following conditions:

❤️ Angina

Angina is the term given to chest pain caused when the heart needs more oxygen than can be provided to it. By slowing down the speed of the heart, beta blockers reduce both the demand for oxygen and the frequency of angina attacks. Current guidelines recommend they are used as first-line treatment for angina when possible, sometimes in combination with another group of drugs called calcium channel blockers.

❤️ Heart failure

Heart failure occurs when the main pumping chamber of the heart (the left ventricle) is unable to contract effectively and forcefully. Beta blockers help to improve this, often in conjunction with a number of other drugs that work on the heart such as ACE inhibitors and aldosterone inhibitors.

❤️ After a heart attack

Current guidelines now recommend that anyone who has had a heart attack should be prescribed a beta blocker as a way of helping reduce the risk of another one occurring. This treatment is usually for life.

❤️ To control high blood pressure

Beta blockers are a very common treatment for blood pressure, often as part of a treatment regimen that includes other drugs such as ACE inhibitors and calcium channel blockers.

Beta blockers can also be prescribed to treat other heart-related conditions such as abnormal heart rhythms and postural tachycardia syndrome (POTS).

Other beta blocker uses

Conditions that can be treated with beta blockers but which are not heart-related include:

• Anxiety

By helping to block stress-causing chemicals, beta blockers can reduce some anxiety symptoms such as palpitations and tremor, although they are not a cure for anxiety itself.

• Migraines

Some people with regular migraines find the frequency of their attacks is reduced by taking beta blockers.

• Glaucoma

Glaucoma is a condition caused by raised pressure inside the eyeball, and using beta blocker eye drops helps reduce this.

• Thyrotoxicosis

Beta blockers can help reduce thyrotoxicosis (an overactive thyroid gland) symptoms including a fast heart rate and tremors.

• Tremors (shakes)

In harmless conditions where the hands and arms can shake for no clear reason and which cause problems with activities such as writing and eating, beta blockers can help to ease the tremors.

Photo credit: altmodern - Getty Images
Photo credit: altmodern - Getty Images

Who should not take beta blockers?

You should not be prescribed beta blockers if you have asthma (they can trigger a severe asthma attack in people with this condition), a very slow heart rate, low blood pressure, and uncontrolled heart failure. There are also certain arrhythmias (problems with the heart rhythm) such as sick sinus syndrome where they are not recommended.

Beta blocker possible side effects

For most people, beta blockers are well tolerated with few if any side effects, and if these do occur they are often mild. However, as with any drug, side effects are possible including:

  • Feeling dizzy or faint.

  • Having cold hands and feet.

  • Tiredness and fatigue.

  • Nightmares and vivid dreams.

  • Erectile dysfunction.

  • Blunting of the awareness of low blood sugar (a ‘hypo’) in people with diabetes as well as a small risk of causing type 2 diabetes to develop in some people.

Beta blocker drug interactions

As with all medicines, beta blockers can interact with other medicines you may be taking. The different types of beta blocker can have different effects with other drugs and your doctor will advise you if there are any potential interactions to be aware of. Because of this, it is important you always tell your doctor or pharmacist of any other medications you are taking before starting to take beta blockers.

Possible beta blocker drug interactions include:

  • Mefloquine, used in the treatment of malaria.

  • Clonidine, a treatment used to treat migraine and high blood pressure.

  • Some antibiotics, including Rifampicin.

  • Statins, used to lower cholesterol levels.

  • Anti-arrhythmic drugs used to treat irregular heartbeats, such as amiodarone and flecainide.

  • Treatments for Parkinson’s disease such as levodopa.

  • Non-steroidal anti-inflammatory drugs, such as ibuprofen.

  • Some antidepressants, such as SSRIs.

If you have any concerns about whether you may be taking other drugs that could interact with beta blockers, discuss this with your doctor.

Stopping beta blockers

If you experience side effects, speak to your GP as soon as possible but do not suddenly stop taking them. This is important since if you have been taking them for some time and your body has become used to them, suddenly stopping can cause your blood pressure to quickly rise or trigger palpitations or an angina attack. It may not be necessary to stop a beta blocker completely as some side effects can be managed by reducing the dose or changing to a selective type.

Last updated: 15-04-2021

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