Heart rate 36 on an adult - what does it mean?
A resting heart rate of 36 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 36 bpm sits on the adult scale
- Very low
- Low (bradycardia)
- Slightly low
- Normal
- Elevated (tachycardia)
- High
- Very high
What a resting pulse of 36 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 36 bpm the heart beats about every 1.67 seconds — roughly 51,840 beats a day.
Could a medicine have pushed the pulse to 36?
When a resting rate drops into the 30s in someone who takes heart medicine, too much drug effect is one of the first things doctors check. Several common prescriptions slow the heart on purpose. At the right dose they keep the rate in a healthy range. Too much of one, or two together, can slow it far more than intended.
The usual suspects are beta blockers (metoprolol, atenolol, carvedilol and others), the calcium channel blockers verapamil and diltiazem, digoxin, and some rhythm drugs such as amiodarone. Clonidine and beta-blocker eye drops for glaucoma can add to the effect. So can donepezil and similar memory medicines used in dementia, which strengthen the nerve signals that brake the heart, though usually less strongly.
How the overdose happens in everyday life
- a dose taken twice by mistake, often when a pill organiser is skipped or refilled
- a new prescription from a second doctor that slows the heart in the same way
- kidney function worsening, so digoxin and some beta blockers build up in the blood
- dehydration from vomiting, diarrhoea or hot weather, which concentrates drugs and disturbs salts
- low potassium, which makes the heart more sensitive to digoxin
- a child or another adult taking pills meant for someone else
Digoxin toxicity has typical extra signs: loss of appetite, nausea or vomiting, confusion, and changes in vision such as blurring, halos around lights or a yellow-green tint.
What to do if you suspect a drug effect
A rate of 36 with dizziness, fainting, confusion, chest pain or breathlessness is an emergency: call 911. If a larger amount of medicine than prescribed has been taken, call 911 or US Poison Control at 1-800-222-1222, even if the person feels fine for now, since some slow-release tablets act hours later.
If you feel well and nothing extra was taken, still see a doctor today. Ask a pharmacist or the doctor before the next dose rather than deciding alone whether to skip it, and never stop a beta blocker abruptly without advice. Bring all medicine boxes with you, including over-the-counter products and supplements, so the team can spot overlaps and order a digoxin level or kidney and potassium tests if needed.
How these medicines fit into heart-rate control in general is explained on the lowering heart rate page.
36 bpm during exercise
36 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 36 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.