A low pulse, medically called bradycardia, is a resting heart rate below 60 beats per minute (bpm) in adults. That threshold isn’t always cause for concern. For many people, especially those who are physically fit, a heart rate in the 40s or 50s is perfectly normal. A low pulse only becomes a problem when your heart isn’t pumping enough blood to keep your brain and organs properly supplied with oxygen.
What Counts as Low by Age
The 60 bpm cutoff applies to adults and adolescents aged 13 and older, whose normal resting range is 60 to 100 bpm. Children have naturally faster hearts. A newborn’s resting rate runs between 100 and 205 bpm, while a toddler’s sits around 98 to 140 bpm. School-age children (5 to 12) typically fall between 75 and 118 bpm. So “low” is relative: a heart rate of 70 bpm is perfectly healthy for an adult but could signal a problem in an infant.
Your pulse also drops significantly while you sleep. During the night, heart rate typically runs 20% to 30% lower than your daytime resting rate, putting most healthy adults somewhere between 50 and 75 bpm. This happens because your nervous system shifts into a lower gear, reducing blood pressure and heart rate, especially during deep sleep. Seeing a number in the low 50s on a sleep tracker is usually not a red flag.
When a Low Pulse Is Normal
Endurance exercise physically remodels the heart. Runners, cyclists, swimmers, and other aerobically fit people develop a stronger heart that pumps more blood per beat, so it doesn’t need to beat as often. Resting rates of 40 to 50 bpm are common in very fit individuals. This is sometimes called “athletic heart,” and it’s a sign of cardiovascular efficiency, not disease.
The key distinction is whether you feel fine. A low number on a fitness tracker means little on its own. If you’re active, have no symptoms, and your pulse is in the 40s or 50s, there’s generally nothing wrong.
Symptoms That Signal a Problem
A low pulse becomes clinically significant when your heart can’t deliver enough oxygen to your body. The symptoms reflect that oxygen shortage:
- Dizziness or lightheadedness, especially when standing up
- Fainting or near-fainting
- Unusual fatigue, particularly during physical activity
- Shortness of breath
- Confusion or trouble focusing
- Chest pain
- Heart palpitations (a fluttering or pounding sensation)
If your heart rate drops below 35 to 40 bpm and you’re experiencing any of these symptoms, that’s a situation that needs immediate medical attention. Chest pain, palpitations, or difficulty breathing alongside a slow pulse are emergency-level warning signs.
Common Causes of a Low Pulse
Medications are one of the most frequent reasons for a slow heart rate. Beta-blockers, which are widely prescribed for high blood pressure, heart failure, and certain heart rhythm problems, work by blocking stress hormones that speed the heart up. They deliberately slow your pulse, sometimes more than intended. If you started a new heart or blood pressure medication and noticed your pulse dropping, the drug is the likely explanation.
Calcium channel blockers, another common class of blood pressure medication, can have a similar effect. So can certain drugs used for irregular heart rhythms, as well as some medications prescribed for completely unrelated conditions like migraines.
Beyond medications, several medical conditions can slow the heart:
- Hypothyroidism: Low thyroid hormone levels slow the heart rate and make arteries less flexible, which is why thyroid problems often show up alongside changes in blood pressure and pulse.
- Heart block: The electrical signals that coordinate your heartbeat can become partially or fully disrupted, causing the heart to beat too slowly. This can result from aging, prior heart surgery, or damage to heart tissue.
- Sick sinus syndrome: The heart’s natural pacemaker (a small cluster of cells in the upper right chamber) can malfunction, producing an unreliable rhythm.
- Electrolyte imbalances: Abnormal levels of potassium or calcium in the blood can interfere with the electrical signals that regulate heart rate.
Age is a factor too. The heart’s electrical system gradually wears down over time, which is why bradycardia and pacemakers are more common in older adults.
How a Low Pulse Is Evaluated
If you visit a doctor about a slow heart rate, the first step is usually an electrocardiogram (ECG), a quick, painless test that records the electrical activity of your heart. This can reveal whether the slow rate comes from a problem with the heart’s pacemaker cells, a block in its electrical pathways, or something else entirely.
Sometimes bradycardia is intermittent, meaning it comes and goes. In that case, you might wear a portable heart monitor for 24 hours to several weeks to catch the slow episodes as they happen. Blood tests to check thyroid function and electrolyte levels are also standard, since these are treatable causes that don’t require any heart-specific intervention.
How a Low Pulse Is Treated
Treatment depends entirely on the cause. If a medication is responsible, adjusting the dose or switching to a different drug often resolves the issue. If hypothyroidism is behind it, treating the thyroid condition brings the heart rate back up on its own.
When the problem lies in the heart’s electrical system and can’t be fixed by addressing an outside cause, a pacemaker is the standard solution. A pacemaker is a small device implanted under the skin near the collarbone. It monitors your heart rate continuously and sends a tiny electrical signal to speed things up whenever your pulse drops too low. The procedure itself typically takes one to two hours, and most people go home the same day or the next morning. Modern pacemakers last 10 to 15 years before the battery needs replacing.
Not every case of bradycardia needs treatment. If your slow pulse causes no symptoms and no underlying condition is found, monitoring over time is often the only recommendation.
Checking Your Pulse at Home
You can measure your resting heart rate by placing two fingers (not your thumb) on the inside of your wrist, just below the base of your thumb. Count the beats for 30 seconds and multiply by two. For the most accurate reading, check first thing in the morning before getting out of bed, or after sitting quietly for at least five minutes. Smartwatches and fitness trackers also provide continuous readings, though occasional inaccuracies are common, especially during movement.
A single low reading doesn’t mean much. What matters is a pattern: consistently low numbers combined with symptoms like fatigue, dizziness, or fainting. If you’re seeing resting rates below 50 and feeling off, that’s worth bringing up at your next appointment. If your rate drops below 35 to 40 and you feel symptomatic, don’t wait.