Could your beta-blocker side effects be a trick of the mind? 

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. If you experience side effects that bother you or last a few days then speak to your doctor.

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 life-saving benefits of beta blockers, unless we can prove that these symptoms are being caused by the nocebo effect instead of the medicine.

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.

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