A dangerous heart rate for a child depends on the child’s age, whether they are resting or active, and how they look overall. In general, a very fast heart rate that stays high while resting, or a very slow heart rate with symptoms, can be concerning and should be checked urgently.
Heart rates are normally higher in babies and younger children, then gradually slow down as children get older. Fever can also raise the heart rate, and studies suggest it may increase by about 10 beats per minute for each 1°C rise in body temperature. Pain, crying, anxiety, exercise, and dehydration can also make the pulse faster for a short time.
A heart rate may be dangerous if it is far above the expected range for age, especially if it is near or above 220 beats per minute in infants or 180 beats per minute in older children, or if the child has chest pain, trouble breathing, fainting, confusion, extreme weakness, pale or blue skin, or poor circulation.
Call 911 or seek emergency care if a child has a very fast heartbeat with serious symptoms. For repeated episodes, a pediatrician or pediatric cardiologist can help check for rhythm problems and decide if treatment is needed.