Heart rate 120 on an adult - what does it mean?

Where 120 bpm sits on the adult scale

What a resting pulse of 120 means

Common temporary causes: caffeine or energy drinks, nicotine, alcohol (also the day after), stress or anxiety, fever or infection, dehydration, a large meal, heat, pain, and recent physical activity. Decongestants, asthma inhalers and thyroid medication can also raise the pulse.

Sit quietly for five minutes and measure again. If your resting pulse is repeatedly above 100, causes worth checking include anemia, an overactive thyroid, heart rhythm disorders such as atrial fibrillation, and low fitness after illness.

Ranges apply to adults and children aged 10 and older, measured at rest (American Heart Association). By the numbers: at 120 bpm the heart beats about every 0.50 seconds — roughly 172,800 beats a day.

Top of the elevated band: deciding how quickly to act on 120

On this site’s adult scale, 120 is the highest value in the elevated band. Above it, readings move into the high range. That step is a sorting aid, not a medical cliff, but a resting pulse of 120 is clearly fast: the heart is beating twice a second while you sit still. During light exercise the same number is completely ordinary. The question is always whether you were truly at rest when you measured.

If you were, it helps to sort the situation into one of three levels of urgency rather than worrying in general.

Three levels: emergency, same day, routine

Call 911 now if a pulse around 120 comes with:

• chest pain, pressure or tightness;
• fainting, or nearly fainting;
• severe shortness of breath, or lips turning blue;
• confusion, slurred speech or weakness on one side;
• a racing beat that began suddenly and will not stop.

See a doctor or urgent care today if:

• the rate stays at 120 after fifteen minutes of quiet rest and you cannot name a cause;
• you also feel dizzy, weak or newly breathless with light activity;
• you have a fever and feel very unwell, or cannot keep fluids down;
• you are pregnant, have known heart disease, or recently started a new medicine;
• the beat feels irregular for the first time.

Book a routine appointment if the cause is obvious and the rate falls back as it fades, such as after coffee, a fright or a fever, but resting readings above 100 keep returning over the following weeks.

Getting a clean reading before deciding

Sit or lie quietly for ten minutes. Check by hand at the wrist for a full minute and feel whether the spacing is steady. Compare with your watch. Then think back over the last hours: food, drink, medicines, how you slept, any pain or temperature.

A reading that falls toward 100 after rest points to a passing trigger. One that stays at 120 regardless of rest is a signal to follow the same-day path above. When you see the doctor, describe how the fast pulse began and what you have measured since. Bring your medicines, including supplements and cold remedies, or a photo of the labels. If you have a watch history, show the graph of the last days: it tells the doctor whether 120 is new, constant or comes in sudden bursts. The normal adult heart rate overview places 120 alongside the other adult ranges.

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.

Nearby values

• 115 bpm
• 116 bpm
• 117 bpm
• 118 bpm
• 119 bpm
• 121 bpm
• 122 bpm
• 123 bpm
• 124 bpm
• 125 bpm

Measured on a child instead? See heart rate 120 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.