Understand health
Could your beta-blocker side effects be a trick of the mind?
Side effects like breathlessness, tiredness and dizziness stop some people from taking their beta blockers. But what if they’re being caused by something else? Cardiology Specialist Registrar Dr Sameer Zaman explains why these symptoms may not always be a side effect of beta blockers.
Published:
4 September 2025
Published:
4 September 2025
On this page
What do beta blockers do?
Beta blockers are widely prescribed medicines often used to treat heart and circulatory conditions.
They slow down your heart rate, which means your heart does not have to work as hard.
They can be used to treat heart failure, heart valve disease, chest pain (angina) and abnormal heart rhythms (arrhythmias), as well as high blood pressure.
If you’ve had a heart attack, you may be prescribed them as part of your recovery.
What are beta-blocker side effects?
Most people do not have any side effects from beta blockers.
However, some people taking beta blockers do experience symptoms such as fatigue, breathlessness, mild dizziness or feeling lightheaded.
People also report feeling depressed, having problems sleeping or erectile dysfunction.
Sometimes these symptoms are genuine side effects caused by the medicine, which slows down the heart rate.
But they may also be a trick of the mind. If you are expecting these side effects, your mind may tell you are experiencing them, when you’re not.
This is called the ‘nocebo effect’.
This means that people may be missing out on live-saving benefits of beta blockers, unless we can prove that these symptoms are being caused by the nocebo effect instead of the medicine.
Want to get fit and healthy?
Sign up to our fortnightly Heart Matters newsletter to receive healthy recipes, new activity ideas, and expert tips for managing your health. Joining is free and takes 2 minutes.
How can side effects be caused by the mind?
You might be familiar with the term the ‘placebo effect’. This is when your symptoms improve after you take a new treatment – even if it’s not effective – because you believe it will work.
The opposite of this is the ‘nocebo effect’. This is when you experience negative symptoms after you start a new treatment because you expect it to cause them.
You may believe a certain medicine or treatment will cause side effects because of something you’ve read or been told before you start taking it.
And if you notice a symptom or feel unwell when you start a new treatment, you may be more likely to think it’s being caused by the medicine.
It can also be hard to tell whether symptoms are caused by a new medicine or the health condition you’re taking it for.
For example, 2 widely reported side effects of beta blockers – breathlessness and weight gain – are also common in people with heart failure and are usually symptoms of the condition rather than a side effect of the medicine.
How common is the nocebo effect with beta blockers?
To work out how often the nocebo effect was experienced by people taking beta blockers for heart failure, researchers compared 33 side effects reported by people taking a dummy pill with those experienced by people taking a real beta blocker.
The study’s 15,000 participants knew they’d be taking either a dummy pill or a beta blocker, but they did not know which they were being given at the time.
The 2013 study in the International Journal of Cardiology found that people taking the dummy pill were just as likely to experience 28 commonly reported side effects as those taking the real beta blocker.
These side effects included headaches, fatigue, weight gain, low blood pressure and erectile dysfunction.
Six side effects were even more likely to be reported by people taking dummy pills, including depression, problems sleeping and chest pain.
This suggests that these ‘side effects' may not have been caused by beta blockers.
Only 5 symptoms – dizziness, low heart rate, muscle pain during physical activity (intermittent claudication), diarrhoea and high blood sugar – were more common in people who were taking beta blockers than those who were taking a dummy pill.
The researchers estimated that for every 100 people who experienced dizziness while taking a beta blocker, 81 people taking a dummy pill also had the symptom.
This means that dizziness was only genuinely caused by beta blockers in 19 out of 100 cases.
Should you stop taking beta blockers if you have side effects?
If you start to experience any symptoms while taking beta blockers, do not stop taking them without speaking to your doctor first – this is because stopping them can cause symptoms like palpitations or make your heart condition worse.
Research shows that beta blockers can be very effective for conditions like heart failure, so it’s important to take them if you’re able to.
One study I co-authored that was published in the European Journal of Heart Failure in 2017 found that taking beta blockers for heart failure reduced the risk of dying by 27 per cent.
If you are one of the few people who are unable to take beta blockers because you have another health condition, or a genuine intolerance to them, your healthcare team can work with you to find another medicine.
How researchers are working out if beta-blocker side effects are real
We’re currently trialling a new way to work out what is really causing people’s symptoms when they’re taking beta blockers.
In our study ENABLE-HF at Imperial College London, which is funded by British Heart Foundation (BHF), we’re asking people with heart failure who previously stopped taking beta blockers to try a low dose of the beta-blocker bisoprolol and record their symptoms.
During the 9-week trial, participants have weeks where they take the genuine beta blocker, weeks where they take an identical dummy pill (no medicine), and weeks where they take no tablet at all.
Every day, they record their symptoms on an app we’ve developed called the ORBITA symptom reporting app, without knowing which pill they’re taking. It only takes a minute a day, but participants can do it over the phone with a doctor on the research team if they cannot use the app.
The beta-blocker bisoprolol next to the identical dummy pill used in the ENABLE-HF trial.
At the end of the 9 weeks, they will receive personalised results, so they can see how strongly they felt their symptoms while taking the beta blocker, compared to how strongly they felt them while taking the dummy pill.
This will help them identify if their symptoms are really side effects of beta blockers or not. And if they start taking beta blockers again, it may even help to reduce the symptoms caused by the nocebo effect.
The trial is similar to an earlier BHF-funded study published in the Journal of the American College of Cardiology in 2021. This study included 60 people who had previously stopped taking statins, which are medicines that lower cholesterol, because they believed they were causing side effects.
It found that people reported similar symptoms during the months they were taking the dummy pills compared to the months they were taking statins.
The results were shared with the study’s participants and 6 months afterwards 50 per cent of them were taking statins again.
If our ENABLE-HF trial is successful, our aim is to develop a clinical service that your GP can refer you to if you experience symptoms while taking beta blockers.
This will help more people take medicines that are proven to be effective, like beta blockers, rather than time and money being sent on developing new drugs.
- Learn more about ENABLE-HF or email [email protected] to find out more about taking part in the study.
What to read next...
Beta blockers: how do they work and do they have side effects?
More useful information
Understand health
Living with heart failure
15 January 2025
Understand health
Shortness of breath: what causes it and how can you manage it?
25 June 2021
19 November 2020
