Beta-blockers are medicines that are used to treat a variety of conditions. Their full correct name is beta-adrenoceptor blocking medicines, but they are commonly just called beta-blockers. There are several types of beta-blocker. They include acebutolol, atenolol, bisoprolol, carvedilol, celiprolol, labetalol, metoprolol, nadolol, nebivolol, oxprenolol, pindolol, sotalol, propranolol and timolol. Each type has one or more brand names.
Beta-blockers work by blocking the transmission of certain nerve impulses. The ends of some nerves release a chemical (neurotransmitter) called noradrenaline when the nerve is stimulated. This chemical then stimulates beta-adrenergic receptors. These receptors are tiny structures which occur on cells in various parts of the body, including the heart, brain, and blood vessels. When these receptors are stimulated, they cause various effects. For example, nerve impulses to the heart can stimulate beta-adrenergic receptors on heart cells. This causes an increase in the force and rate of the heartbeat.
The beta-adrenergic receptors are also stimulated by adrenaline (epinephrine), a hormone which circulates in the bloodstream. Adrenaline is made in the adrenal gland. The blood level of adrenaline can vary. For example, you may release a lot of adrenaline into the bloodstream when you are frightened or anxious which can cause an increase in your heart rate, and other effects.
The beta-blocker medicine 'sits' on beta-adrenergic receptors and stops (blocks) the receptor from being stimulated. So, for example, if beta-adrenergic receptors in the heart are blocked, the force and rate of the heartbeat are reduced.
Which conditions are treated with beta-blockers?
Heart and blood vessel conditions
Because of their effect on the heart cells, beta-blockers may be used to:
- Prevent angina pains.
- Reduce the risk of a further heart attack (myocardial infarction) if you have already had one.
- Control certain abnormal heart rhythms (arrhythmias).
- Help to treat heart failure.
- Lower your blood pressure if it is too high.
- Treat postural tachycardia syndrome (PoTS).
Because beta-adrenergic receptors are found in other parts of the body, beta-blockers are also used for various other conditions. These include:
- Glaucoma. Beta-blocker eye drops reduce the fluid that you make in the front chamber of the eye. This reduces the pressure in the eye.
- Anxiety. Beta-blockers do not reduce anxiety itself but can reduce some of the symptoms. For example, they can reduce shaking (tremor) and a fast heart rate.
- Overactive thyroid gland. Beta-blockers can help to reduce symptoms such as tremor, and slow down a fast heart rate.
- Migraine. Beta-blockers can reduce the number of migraine attacks if the attacks occur frequently.
- Tremors - beta-blockers can be used in benign arm tremors which have no other underlying cause and are causing significant problems in daily activities.
Most people who take beta-blockers have no side-effects, or only minor ones. However, because of their action in various parts of the body, some people have unwanted side-effects. For example:
- Sometimes the heart rate can go too slowly. This can make you dizzy or feel faint.
- If you have diabetes you need to be aware that beta-blockers may dull the warning signs of a low blood sugar level (hypoglycaemia - often called a hypo). For example, you may not develop the sensation of rapid, irregular or forceful heartbeats (palpitations) or tremor, which tend to occur as the blood sugar is going too low.
- Some people develop cool hands and feet when taking beta-blockers. This is because they can narrow (constrict) small blood vessels and reduce the circulation to the skin of the hands and feet.
- Tiredness, depression, inability to achieve a proper erection (impotence), vivid dreams, nightmares and other sleeping problems occur in some people.
- There is some evidence to suggest that beta-blockers may provoke type 2 diabetes to develop in some people.
Some people with asthma are advised not to take a beta-blocker. If you have asthma or something similar, discuss this with your GP.
The above is not a full list of possible side-effects but mentions the main ones that may occur. Read the information leaflet that comes with your particular brand for a full list of possible side-effects and cautions.
What is the usual length of treatment?
The length of treatment depends on why you are taking a beta-blocker. Some people only need to take beta-blockers for a few weeks, or months - for example, if you have an overactive thyroid. Some people need to take beta-blockers for the rest of their lives - for example, after a heart attack (myocardial infarction).
Who cannot take beta-blockers?
You cannot take a beta-blocker if you have certain conditions, including:
- Uncontrolled heart failure.
- Very slow heart rate (bradycardia).
- Low blood pressure (hypotension).
- Certain problems with the rhythm of your heart - eg, sick sinus syndrome.
How to use the Yellow Card Scheme
If you think you have had a side-effect to one of your medicines you can report this on the Yellow Card Scheme. You can do this online at www.mhra.gov.uk/yellowcard.
The Yellow Card Scheme is used to make pharmacists, doctors and nurses aware of any new side-effects that medicines or any other healthcare products may have caused. If you wish to report a side-effect, you will need to provide basic information about:
- The side-effect.
- The name of the medicine which you think caused it.
- The person who had the side-effect.
- Your contact details as the reporter of the side-effect.
It is helpful if you have your medication - and/or the leaflet that came with it - with you while you fill out the report.
Further reading and references
Management of atrial fibrillation; NICE Clinical Guideline (June 2014)
Acute coronary syndrome; Scottish Intercollegiate Guidelines Network - SIGN (2016)
2016 ESC Guidelines for the diagnosis and treatment of acute and chronic heart failure; European Society of Cardiology (ESC)
Hypertension overview; NICE Pathway, August 2011
Migraine; NICE CKS, August 2017 (UK access only)
Metoprolol has been the worst medication I've ever been on. After a year of not knowing what was making me sick we found out it's this poison. I have never suffered so much and now after so much I...Tee19
Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. Patient Platform Limited has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.