What Is a Dangerous Heart Rate? Ranges, Symptoms, and More

Medically Reviewed By Dr. Payal Kohli, M.D., FACC
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Heart rate is the number of times your heart beats in 1 minute. A rate that is too high or too low can affect how blood and oxygen circulate in the body. A dangerous heart rate can lead to serious health effects. A high or low heart rate may indicate a serious underlying condition. Therefore, it is important to know the signs and symptoms of an irregular or unsafe heart rate.

This article discusses heart rates, what is safe and dangerous, and the symptoms of dangerous heart rates. It explains when to seek medical help and answers frequently asked questions about heart rates.

What is a normal heart rate? 

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According to the American Heart Association (AHA), the standard resting heart rate for adults is 60–100 beats per minute (bpm). 

However, some factors can cause expected or benign variations in heart rate temporarily. For example:

Additionally, standard or expected heart rates can vary depending on individual factors. These factors include age, activity levels, and fitness.

An older, 2014 study suggests that there may be slight variations in the average heart rates of people assigned male at birth and people assigned female at birth. Researchers observed that the average adult male heart rate is 70–72 bpm and that for adult females is 78–82 bpm. Heart size may cause the difference. The heart is usually bigger in males.

Identifying your own typical resting heart rate helps you know when it has become too high or too low. To do this, measure your pulse during 1 minute at rest.

Learn more about typical heart rate ranges, including typical heart rates in children.

Target and maximum heart rates

Everyone has a maximum safe heart rate that they should try not to exceed.

According to the AHA, to calculate your maximum heart rate, subtract your age from the number 220. For example, if you are 25 years old, your maximum heart rate will be about 195 bpm.

Target heart rate refers to your ideal heart rate. Target heart rate typically is calculated as a percentage of your maximum heart rate.

The AHA recommends a target heart rate of 50–85% of your maximum heart rate during moderate to vigorous physical activity.

The AHA lists examples of average maximum heart rates and target heart rates while active for adults, as follows:

Age (years)Average maximum heart rate (bpm)Target heart rate while active (bpm)
20 200100–170
50 17085–145

These values are averages and estimations. The AHA recommends using them only as a general guide.

What is a dangerously low heart rate?

Clinicians may refer to a low heart rate as “bradycardia.”

A heart rate that clinicians consider to be too low depends on individual factors, such as age. However, in general, a resting heart rate of less than 60 bpm in adults is bradycardia.

Read more about slow heartbeat and its complications.


Some cases of bradycardia are harmless. However, a serious underlying condition may cause bradycardia. Causes of bradycardia that are not benign and require medical care include:

  • hypothyroidism 
  • sleep apnea
  • cardiovascular disease, such as pericarditis or heart attack
  • neuromuscular conditions, such as muscular dystrophy
  • sick sinus syndrome
  • amyloidosis
  • Lyme disease
  • rheumatic fever
  • chest trauma or injury
  • genetic variations or conditions

Some treatments or medications can cause a low heart rate. These include:


A dangerously low heart rate can be symptomatic in some people and asymptomatic in others. This means you may not know whether your heart rate is within a standard range without checking.

Symptomatic cases can lead to:

  • fainting 
  • shortness of breath
  • difficulty when exercising
  • heart palpitations
  • fatigue or tiredness
  • dizziness or lightheadedness
  • chest pain 
  • confusion

What is a dangerously high heart rate? 

A dangerously high heart rate, also known as tachycardia, is when your heart beats too quickly. Similarly to bradycardia, the exact heart rate that is too fast depends on individual factors.

Generally, a heart rate of more than 100 bpm while not exercising qualifies as tachycardia in adults.

According to the AHA, there are three main types of tachycardia: 

  • Atrial or supraventricular tachycardia (SVT): Electrical signals that control the upper chambers of the heart go off atypically. This causes fast contractions, which interrupt blood flow in the heart and impede blood supply to the body. 
  • Ventricular tachycardia: Electrical signals that control the lower chambers of the heart go off atypically. Similarly to SVT, ventricular tachycardia also affects blood flow through the heart and disrupts blood supply to the body. 
  • Sinus tachycardia: The heart’s pacemaker, the sinoatrial node, transmits electrical signals faster than usual. This accelerates heart rate but does not affect the way the heart beats.

Learn more about fast heart rate and its complications.


Causes of tachycardia include:


Symptoms of tachycardia can include:

In extreme cases, heart attack or unconsciousness may occur.

When should I seek medical help?

You typically will not require medical attention if your heart rate temporarily falls outside the standard range due to benign causes.

However, you may wish to seek medical care if you:

  • experience recurring episodes of an unusual heart rate
  • have anxiety due to heart rate change
  • experience a heart rate change after taking a new medication
  • suspect an infection or another underlying medical issue

Seek emergency care for the following symptoms

If you notice serious symptoms alongside a change in heart rate, seek emergency medical care or call 911. These symptoms include:

How do doctors diagnose heart rate changes? 

A doctor will review your symptoms and medical history to investigate for any underlying causes. This can also involve a physical examination to measure your heart rate or blood pressure.

Doctors may also perform further tests or scans to check for underlying conditions. These tests may include:

What is the outlook for a high or low heart rate?

Brief heart rate changes are usually not a cause for concern when associated with temporary and benign factors, such as exercise.

Severe or recurring heart rate changes may indicate an underlying medical condition. Serious cases can lead to complications such as permanent heart damage or death. However, early identification of symptoms allows you to access effective treatment quickly. Prompt treatment may help to improve your outcome.

If you are concerned about your heart rate, contact a doctor immediately for advice.

Seek emergency medical care for serious symptoms alongside a low or high heart rate.

Other frequently asked questions 

Payal Kohli, M.D., has reviewed the following frequently asked questions.

What is a dangerous heart rate for a child?

A typical heart rate range can vary greatly depending on a person’s age and physical condition. Additionally, heart rates tend to slow with increased age. For example, what is standard for a 5-year-old may be concerning in a 7-year-old.

To find a child’s typical heart rate, you can measure their pulse while they are resting. If you notice later that their heart rate is significantly increased or decreased beyond this typical rate, and they are experiencing additional symptoms, contact your doctor for advice.

An increased heart rate while exercising and decreased heart rate while sleeping is normal.

What is a dangerously low heart rate when sleeping?

Deep sleep naturally causes a person’s heart rate to drop. The exact rate that is dangerous for you will depend on individual factors.

However, prolonged pauses or irregular patterns in your heartbeat while sleeping can be dangerous, especially if you also experience sleep apnea.

What is a dangerous heart rate for a woman?

The average resting heart rate for adults, including those assigned female at birth, is 60–100 bpm. A heart rate that falls significantly above or below this range outside of sleep and exercise may be dangerous.


The normal resting heart rate for adults is 60–100 bpm. Some factors, such as sleep, exercise, and anxiety can cause expected and temporary variations.

Low and high heart rates occur outside of these ranges. Some cases of high and low heart rates can be benign. Some conditions such as heart attacks are serious and require emergency medical care.

Seek emergency medical treatment for changes to heart rate along with confusion, difficulty breathing, or pain, or if you have underlying health conditions.

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Medical Reviewer: Dr. Payal Kohli, M.D., FACC
Last Review Date: 2022 Sep 29
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
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