Low heart rate symptoms: when a slow heart rate is normal, what it can point to and when to see a doctor

When your heart rate is low

In this article you will read when a slow heart rate is normal, which low heart rate symptoms matter, what a low heart rate can point to, what the risk is and when to see a doctor. That matters, because a slow heart rate is often a sign of nothing at all, and the few signals that do count are easy to miss among the many that do not. The BioProfile heart scan gives you an indication of where you stand today with your heart and blood vessels. The scan is not a diagnosis. It is self-insight, to see where you stand today and to help you make better choices in your diet and lifestyle. The scan does not find a cause. Only a doctor can assess that.

At rest, an adult’s heart usually beats between 60 and 100 times a minute, and a heart rate below 60 is called bradycardia.⁠^1,5 A heart rate below 60 is not automatically a problem.⁠¹ Well-trained athletes often have a lower resting heart rate,⁠¹ and the European guideline on slow heart rhythms also names young people and sleep as times when a slow rhythm is simply part of how the body works.⁠² You can read more about the normal values on our page about a normal heart rate.

So a low number on its own says little. What matters is whether symptoms come with it.

Low heart rate symptoms

A slow heart rate often causes no symptoms at all.⁠⁵ Symptoms appear when the brain gets too little blood: dizziness, fainting, tiredness, trouble concentrating and memory problems.⁠¹ If the heart rate is much slower, shortness of breath can come with it too.⁠⁵ For older people, Thuisarts names a slow heart rate as one of the things that can make you feel light-headed.⁠⁴

Put simply, the symptoms of a heart rate that is too low are the signals of a brain that is getting just a little too little blood. A low reading on your watch without any of these symptoms is usually no reason for concern.⁠¹

What a low heart rate can point to

Every cause falls into one of two groups. In the heart: a sinus node that fires too slowly, or wear of the heart’s conduction system. Outside the heart: vomiting, coughing, raised pressure in the brain, a low body temperature, some medicines and thyroid problems.⁠⁵ The Hartstichting also names a disturbed balance of minerals and heart disease.⁠¹ The European guideline names beta blockers among the medicines that slow the sinus node, and an underactive thyroid as a metabolic cause.⁠²

In older people, medicines often play a part. A British hospital looked at four months of admissions and found 100 patients over 70 with a slow heart rate that kept coming back. In 62 of them, the slow heart rate was linked to a medicine, in 54 of those 62 to beta blockers, and bisoprolol was the one that came up most often. The average age in that group was 83. In 23 of the 100 patients, fainting was one of the reasons for the admission.⁠⁶

What this means for you: if you take a medicine that slows the heart and your symptoms keep coming back, that is a reason to see your doctor.⁠¹

The risk of a heart rate that is too low

An American study followed 6,733 adults without heart disease, with an average age of 62, for about ten years. Of the 5,831 who took no medicine that slows the heart, about one in twenty had a resting heart rate below 50. In them, that low heart rate without symptoms was not linked to more heart disease or dying earlier. In the 902 who did take such a medicine, a heart rate below 50 went together with a risk of death more than twice as high.⁠³

Put simply: in this study, a very slow heart rate in someone who feels well and takes no heart medicine seemed harmless. The same number in someone who takes a heart medicine deserves more attention.

A second American study followed 19,893 adults for 17 years. Of them, 213 developed sick sinus syndrome, a disorder of the sinus node. That group died early more often, had a risk of heart failure almost three times as high and a risk of atrial fibrillation almost six times as high, and needed a pacemaker far more often.⁠⁷

So the risk lies less in the slow heart rate itself than in what is causing it.

Across 87 studies taken together, a higher resting heart rate went hand in hand with more risk: every 10 extra beats per minute meant a higher risk of death from any cause, of heart disease, of heart failure and of stroke. For atrial fibrillation the pattern was different, and the risk did not simply rise along with the heart rate.⁠⁸

For most people, then, a calm, slow heart rate at rest is not a warning sign in itself.

When to see a doctor

Thuisarts gives older people two clear signals. If you are suddenly dizzy, call your GP or the out-of-hours GP service straight away. If you are dizzy and your heart suddenly beats irregularly, faster and then slower again, or very fast, call within a few hours.⁠⁴ The Hartstichting also names three reasons to see a doctor: symptoms that keep coming back together with a low heart rate, being dizzy regularly, because that brings a risk of falling, and a heart rate that does not rise with exertion or emotion.⁠¹ Weakness or a tendency to faint is also a reason to go.⁠⁵

A doctor will ask how often your symptoms come, how severe they are and how long they last,⁠² so it helps to write that down beforehand. You can read more about heart symptoms in women more broadly in heart symptoms in women.

In summary

In this article you read that a heart rate below 60 is called bradycardia and is often normal, in athletes, in young people and during sleep. Symptoms of a low heart rate arise because the brain gets too little blood. A slow heart rate can point to the sinus node, the conduction system, the thyroid or a medicine. Without symptoms the risk is usually small, and sudden dizziness is a reason to call your GP straight away.