Heart rate 103 on an adult - what does it mean?

Where 103 bpm sits on the adult scale

What a resting pulse of 103 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 103 bpm the heart beats about every 0.58 seconds — roughly 148,320 beats a day.

Down with the flu and a pulse of 103

Fever is one of the most reliable ways to push a resting pulse past 100. A higher body temperature speeds up the body’s chemistry, and the tissues need more oxygen. The heart answers by beating faster. A rough rule is about 10 extra beats per minute for each degree Celsius of fever, which works out to a little over 5 beats for each degree Fahrenheit.

Put that into numbers. Someone who normally rests at about 80 and has a temperature of around 102 °F (just under 39 °C) can easily read 100 or more. A pulse of 103 during the flu is therefore what you would expect, not a separate problem. Fluid loss from sweating, a poor appetite and broken sleep add a few more beats.

Watching the pulse follow the fever

Because pulse and temperature move together, they make a useful pair to track while you are ill. Measure both at the same time, two or three times a day, and write them down. When a fever reducer brings your temperature down, the pulse usually drops with it within an hour or two. As the infection clears over several days, both numbers should drift back toward your normal.

A few patterns are worth noticing:

• Pulse much higher than the fever explains, for example above 120 with only a mild temperature: let a doctor know.
• Pulse stays fast after the fever is gone: often just slow recovery and lost fluid, but if it lasts more than a few days, or comes with chest pain or new breathlessness, get it checked.
• Readings improving, then worsening again: can mean a second infection, such as pneumonia after the flu.

Rest, plenty of fluids and the usual flu care help both the temperature and the heart rate. Easing off exercise until you are fully better is sensible; our page on resting heart rate explains how to tell when your baseline has returned.

When an infection becomes dangerous

A fast pulse with fever is normal. A fast pulse with fever and any of the following is not: confusion or unusual sleepiness, very fast breathing, skin that is cold, blotchy or bluish, severe weakness, very little urine, or feeling that something is badly wrong. These can be signs of sepsis, the body’s extreme response to an infection, and need 911 or the emergency room without delay.

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

• 98 bpm
• 99 bpm
• 100 bpm
• 101 bpm
• 102 bpm
• 104 bpm
• 105 bpm
• 106 bpm
• 107 bpm
• 108 bpm

Measured on a child instead? See heart rate 103 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.