A resting heart rate of 38 bpm is well below the normal adult range of 60 to 100 beats per minute and falls into the category of bradycardia, which is any heart rate under 60. Whether 38 bpm is dangerous depends on two things: whether you have symptoms and whether there’s an underlying cause. For most people, a heart rate this low warrants medical evaluation.
Why 38 BPM Raises Concern
The normal resting heart rate for adults sits between 60 and 100 bpm. Trained endurance athletes can have resting rates in the 40s or even high 30s because their hearts pump more blood per beat, so fewer beats are needed. But if you’re not someone who trains intensively, a rate of 38 suggests your heart’s electrical system may not be firing correctly or something else is slowing it down.
The Cleveland Clinic advises seeking medical attention right away if your heart rate drops below 35 to 40 bpm and you’re experiencing symptoms like shortness of breath, chest pain, or dizziness. At 38, you’re right at that threshold.
Symptoms That Signal a Problem
A slow heart rate becomes dangerous when your body isn’t getting enough blood flow. The signs that 38 bpm is causing trouble include:
- Dizziness or lightheadedness
- Fainting or near-fainting episodes
- Shortness of breath
- Unusual fatigue or weakness
- Chest pain or pressure
- Confusion or difficulty concentrating
If you have none of these symptoms and you’re a highly conditioned athlete, 38 bpm may simply reflect an efficient heart. Some elite endurance athletes live with resting rates in this range without any health consequences. The key distinction is fitness-related bradycardia versus something pathological.
What Can Cause a Heart Rate This Low
Several medical conditions can push your resting heart rate into the 30s. Heart tissue damage from aging, prior heart attacks, or heart disease is one of the most common causes. The heart’s natural pacemaker (a cluster of cells at the top of the heart) can degrade over time, slowing the electrical signals that trigger each beat.
Other causes include an underactive thyroid, which slows many body processes including heart rate, and imbalances in potassium or calcium levels. Obstructive sleep apnea, inflammatory conditions like lupus or rheumatic fever, and infections that inflame heart tissue (myocarditis) can also be responsible. Some people are born with heart defects that affect the electrical conduction system.
A condition called heart block occurs when electrical signals between the upper and lower chambers of the heart are delayed or partially blocked. In more severe forms, this can drop the heart rate into the 30s or lower and often requires treatment.
Medications That Slow Heart Rate
A common and often overlooked cause is medication. Beta-blockers, prescribed for high blood pressure and heart conditions, directly reduce heart rate. Calcium channel blockers like diltiazem and verapamil do the same. Digoxin, certain antidepressants (including some SSRIs), sedatives, opioids, and the blood pressure drug clonidine can all push heart rate down significantly. Even beta-blocker eye drops used for glaucoma have been linked to bradycardia. If you’re on any of these medications and seeing a heart rate of 38, your dosage may need adjustment.
What Happens During Sleep
If you noticed 38 bpm on a fitness tracker overnight, that context matters. Heart rate naturally drops during sleep, particularly during deep sleep phases. A healthy adult’s sleeping heart rate typically runs between 50 and 75 bpm, so 38 is still low even by nighttime standards. Brief dips into the high 30s during deep sleep can occur in fit individuals, but if your tracker consistently shows rates in the 30s throughout the night, it’s worth mentioning to a healthcare provider.
How a Low Heart Rate Gets Evaluated
The primary tool for evaluating bradycardia is an electrocardiogram (EKG), which records the electrical activity of your heart through sensors placed on your chest. It takes only a few minutes and can reveal whether the slow rate is caused by a problem with the heart’s pacemaker cells or a block in the electrical pathway between heart chambers.
Because a slow heart rate can come and go, a single EKG might look normal if your rate happens to be higher during the office visit. In that case, you may be asked to wear a Holter monitor, a portable device that records your heart rhythm continuously for 24 hours or longer. An event recorder works similarly but can be worn for up to 30 days, and you press a button when you feel symptoms so the device captures exactly what your heart is doing at that moment.
Blood tests are typically part of the workup too, checking thyroid function, potassium, calcium, and signs of infection. If fainting has been an issue, a tilt table test may be used: you lie flat on a table that’s gradually tilted upright while your heart rate and blood pressure are monitored. A sleep study may be recommended if sleep apnea is suspected.
What Untreated Bradycardia Can Lead To
When a heart rate of 38 bpm is truly symptomatic and left unaddressed, the consequences go beyond feeling tired or dizzy. Chronically inadequate blood flow means your organs, including your brain, aren’t getting the oxygen they need. Over time, this can contribute to heart failure, where the heart can no longer pump effectively enough to meet the body’s demands. Repeated fainting episodes carry their own risks, from falls and fractures to accidents while driving.
Treatment depends entirely on the cause. If a medication is responsible, adjusting the dose or switching drugs often resolves the problem. If an underactive thyroid is to blame, thyroid hormone replacement typically brings the heart rate back up. For structural or electrical problems within the heart itself, a pacemaker (a small device implanted under the skin that sends electrical impulses to maintain a minimum heart rate) is the standard solution and is one of the most common cardiac procedures performed.
A single reading of 38 bpm on a wrist device isn’t necessarily cause for alarm, as consumer trackers can occasionally misread. But if you’re consistently seeing rates in the 30s, especially while awake, or if you’re experiencing any of the symptoms listed above, that’s a reading worth acting on promptly.