A resting heart rate of 48 beats per minute is below the standard “normal” range of 60 to 100 bpm, but it’s not automatically a problem. For physically active people and trained athletes, a resting heart rate in the 40s is common and actually signals a strong, efficient heart. Whether 48 bpm is good news or a red flag depends almost entirely on how you feel and what’s causing it.
Why 48 bpm Can Be a Sign of Fitness
Your heart is a muscle, and like any muscle, it gets stronger with regular use. When you exercise consistently, your heart adapts by pumping more blood with each beat. That means it doesn’t need to beat as often to circulate the same amount of blood through your body. Very fit athletes can have resting heart rates closer to 40 bpm for exactly this reason.
A large study published in BMJ Heart followed nearly 3,000 men over 16 years and found that the lowest mortality risk belonged to men with resting heart rates at or below 50 bpm. Compared to that group, men with resting heart rates between 51 and 80 bpm had a 40 to 50 percent higher risk of death from any cause. Those with rates above 90 bpm had triple the risk. For every 10 bpm increase in resting heart rate, mortality risk climbed about 16 percent, even after accounting for fitness level and other cardiovascular risk factors. So if your 48 bpm reflects genuine cardiovascular fitness, it’s not just normal. It’s associated with better long-term health.
When 48 bpm Is Worth Investigating
A resting heart rate of 48 deserves attention if you’re not particularly active or if it came on suddenly. The key question is whether you have symptoms. Bradycardia (the medical term for a slow heart rate) becomes a concern when it causes dizziness, lightheadedness, fainting, unusual fatigue, shortness of breath during normal activities, or difficulty concentrating. These symptoms suggest your heart isn’t pumping enough blood to meet your body’s needs.
If you have no symptoms and feel fine during exercise and daily life, treatment is generally not needed. But if you’ve noticed a new drop in heart rate and can’t explain it through fitness, it’s worth checking with a doctor to rule out underlying causes like thyroid problems or electrical issues in the heart.
Medications That Can Lower Your Heart Rate
Several common medications slow the heart as either their intended effect or a side effect. Blood pressure drugs are the most frequent culprits: beta-blockers work by directly suppressing the heart’s natural pacemaker cells, and certain calcium channel blockers (diltiazem, verapamil) do the same. If you take either of these, a heart rate of 48 may simply reflect your medication doing its job, though your prescriber should know about it.
Other drugs that can push your heart rate into the 40s include certain antidepressants (particularly SSRIs like citalopram and escitalopram), heart rhythm medications like amiodarone, digoxin (used for heart failure), and clonidine. Even beta-blocker eye drops prescribed for glaucoma can lower heart rate enough to matter. If you started a new medication and noticed your pulse dropping, that connection is worth raising with whoever prescribed it.
How to Measure Your Resting Heart Rate Accurately
The number on your wrist or fitness tracker only means something if you measure it correctly. Harvard Health recommends avoiding a reading within one to two hours after exercise, since your heart rate stays elevated after strenuous activity. Wait at least an hour after caffeine, which can artificially raise your pulse. Don’t measure after sitting or standing in one position for a long time, as that can skew results too.
The most reliable reading comes first thing in the morning, before you get out of bed, when your body is closest to a true resting state. Take it a few times over different days rather than relying on a single measurement. One reading of 48 bpm on a smartwatch after a nap doesn’t carry the same weight as consistently seeing 48 across multiple mornings.
It’s also worth knowing that your heart rate naturally drops during sleep, typically running 20 to 30 percent lower than your daytime resting rate. So if your wearable recorded 48 bpm overnight, that’s well within normal range for sleep, even for someone whose daytime resting heart rate sits in the 60s or 70s.
Age and Context Matter
A 48 bpm resting heart rate in a 25-year-old who runs regularly is almost certainly a marker of fitness. The same number in a sedentary 70-year-old who’s never seen it that low before tells a different story. As a general guideline, seek prompt medical attention if your heart rate drops below 35 to 40 bpm, or if any heart rate is accompanied by chest pain, palpitations, shortness of breath, or dizziness.
For most people reading this, 48 bpm with no symptoms is reassuring, not alarming. It sits in the range where the strongest cardiovascular outcomes have been observed, provided it reflects a healthy heart doing its work efficiently rather than a heart that’s struggling to keep pace.