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Slow heart rate

Also called: Bradycardia, low heart rate

A slow heart rate (under 60 beats per minute) can be normal in athletes and during sleep. It becomes a concern when it causes dizziness, fainting, tiredness, or shortness of breath. Medicines, an underactive thyroid, and heart rhythm problems are common causes. A slow pulse with fainting or chest pain needs 911.

Common causesFitness, sleep, medicines, heart block, hypothyroidism
Usually serious?Sometimes
Get checked ifYou have dizziness, fainting, or shortness of breath
If you think it's an emergency, call 911.Thinking about suicide? Call or text 988.

Overview

A normal resting heart rate is 60 to 100. Fit people often have rates in the 40s or 50s without problems.

Bradycardia can cause tiredness, dizziness, fainting, confusion, and trouble exercising when the heart doesn't pump enough blood. Causes include aging of the heart's electrical system (sick sinus syndrome, heart block), medicines like beta-blockers, and other conditions.

When to get medical care

Call 911Slow pulse with fainting, chest pain, shortness of breath, or confusion.
Get care todaySlow pulse with dizziness or extreme tiredness. Slow pulse after starting a new heart medicine.
See a doctor soonHeart rate under 50 with tiredness or trouble exercising. A slow pulse found on a watch or monitor with symptoms.

Causes

Causes include being very fit, sleep, medicines (beta-blockers, calcium channel blockers, digoxin, some others), sick sinus syndrome, heart block, heart attack, underactive thyroid, high potassium, sleep apnea, and Lyme disease.

OwieClear has pages on 2 conditions that can cause slow heart rate. Each shows how soon to get care.

Common causes

What you can do at home

  • Check your pulse and note symptoms.
  • Don't stop heart medicines on your own; call your provider.
  • Get up slowly if you feel dizzy.

Medicines

Treatment depends on the cause. Your provider may change medicines or treat thyroid problems. A pacemaker may be needed for some heart rhythm problems.

At the doctor

An ECG and heart monitor show the heart rhythm.

Questions you may be asked

  • Your usual heart rate
  • Dizziness or fainting
  • Medicines
  • Exercise habits

The exam

A physical exam, including pulse and blood pressure.

Tests

  • ECG
  • Heart monitor
  • Blood tests including thyroid and electrolytes
  • Exercise test

Prevention

Know your numbers.

  • Review medicines regularly
  • Keep follow-up visits

Check your symptoms

Most symptoms have more than one possible cause. The symptom checker looks at all of your symptoms together, plus your age, and shows how soon to get care.

Start the symptom checker

Sources

Last updated 2026-11-13.