Heart rate 33 on an adult - what does it mean?
A resting heart rate of 33 bpm is very low for an adult. Outside of elite endurance athletes and deep sleep, a pulse under 40 is unusual: see a doctor promptly, and call 911 (US) or your local emergency number if you feel faint, have chest pain or are short of breath.
Where 33 bpm sits on the adult scale
- Very low
- Low (bradycardia)
- Slightly low
- Normal
- Elevated (tachycardia)
- High
- Very high
What a resting pulse of 33 means
Very slow resting rates in people who are not highly trained can mean the heart's electrical system is not keeping pace — for example sinus node dysfunction or a heart block — or can be a medication effect (beta blockers, some calcium channel blockers, digoxin). An underactive thyroid, low body temperature and electrolyte problems are other causes.
Rule out a measuring error first: a weak or irregular pulse is easy to undercount by hand, and some wrist wearables miss beats. Count for a full 60 seconds at the wrist or use a chest-strap or blood-pressure monitor.
Ranges apply to adults and children aged 10 and older, measured at rest (American Heart Association). By the numbers: at 33 bpm the heart beats about every 1.82 seconds — roughly 47,520 beats a day.
A pulse of 33 after cold exposure
Body temperature and heart rate are tightly linked. Just as a fever speeds the pulse, a falling core temperature slows it. Cold slows the chemical reactions in every cell, including the cells that set the heartbeat. When the core drops below about 35 °C (95 °F), doctors call it hypothermia, and as it deepens the heart rate can sink into the 30s, the breathing slows and the blood pressure falls.
Hypothermia is not only a problem for mountaineers. It happens after a fall at home when an older person lies on a cold floor for hours, after immersion in cold water, in people sleeping outdoors, and when alcohol or certain drugs blunt the urge to seek warmth. Wet clothing and wind make it much faster.
Signs that go with a cold, slow heart
- shivering at first, which may stop as the body gets colder
- pale or bluish, cold skin, including on the chest and belly
- clumsy hands, stumbling and slurred speech
- drowsiness, confusion or odd behaviour, such as removing clothes
- a weak, slow pulse and shallow breathing
Moderate or severe hypothermia is a medical emergency. Call 911. While waiting, move the person somewhere warm and sheltered, handle them gently, replace wet clothes with dry ones, and cover the head and body with blankets. Warm, sweet, non-alcoholic drinks help only if the person is fully alert and can swallow safely. Rough rubbing of the arms and legs is not advised.
Milder cold effects and other causes to rule out
Not every chilly reading means hypothermia. Putting your face into cold water triggers the diving reflex, which slows the heart sharply for a short time. Cold hands can also fool a wrist sensor into a falsely low number. Warm up for 20 minutes and measure again with a cuff or a chest strap.
If your core temperature is normal and the pulse stays near 33, look elsewhere. An underactive thyroid lowers both temperature and heart rate, and people often notice feeling cold all the time before anything else. Heart-slowing medicines and conduction problems are other possibilities. A resting 33 in a warm, awake adult needs a medical check today.
A digital thermometer reading under the tongue is a useful first step at home. Note it alongside the pulse, because the pairing of a low temperature and a slow heart rate points the doctor in a specific direction.
33 bpm during exercise
33 bpm is below half of the estimated maximum heart rate at every adult age, so it is a resting-range value, not an exercise intensity. During light activity most adults are already above 90 bpm.
For a reliable resting value, sit quietly for five minutes first and average a few mornings: Resting Heart Rate: What It Says About Your Health. You can also measure by tapping along on the start page.
Check another reading
Nearby values
Measured on a child instead? See heart rate 33 in a child.
Sources: American Heart Association: All About Heart Rate · MedlinePlus: Pulse · ACSM position stand on exercise intensity (2011)
This page explains a single reading in general terms. It is not a diagnosis. Heart rate alone cannot tell whether the rhythm is regular or whether the heart is healthy — if you are worried, talk to a doctor.