Is it dangerous if your heart rate exceeds 120 during a fever?

Fever generally refers to an elevated body temperature, and a heart rate exceeding 120 means the heartbeat is over 120 beats per minute. If a patient's heart rate exceeds 120 beats per minute due to fever, this situation is usually dangerous and requires prompt medical treatment to prevent harm to health.

Fever occurs when the body is affected by pyrogenic substances or when there is dysfunction of the body's temperature regulation center, resulting in increased heat production without a corresponding increase—or even reduced—heat dissipation. A body temperature of 37.3°C or higher is typically considered fever. Heartbeat refers to the pulsation of the heart: the right atrium receives venous blood from the entire body, which is then pumped through the right ventricle into the pulmonary artery. After gas exchange in the lungs, the oxygenated blood returns to the left atrium, meeting the body's normal physiological needs.

If a patient develops a heart rate exceeding 120 beats per minute due to fever, it may damage physical health. Without timely treatment, myocardial injury could occur. Moreover, prolonged fever can lead to multi-organ damage, affecting liver and kidney function, the circulatory system, and the respiratory system. In cases of severe dehydration, shock may also develop. A heart rate over 120 beats per minute during fever often occurs when body temperature exceeds 38°C; for every 1°C rise in body temperature, heart rate increases by 10–15 beats per minute. As body temperature returns to normal, heart rate typically normalizes as well.

It is recommended that patients take medications such as ibuprofen tablets, acetaminophen (paracetamol) tablets, or aspirin tablets under a doctor’s guidance to effectively reduce fever. Additionally, patients should drink plenty of water to stay hydrated and prevent dehydration, and consume moderate amounts of fresh fruits and vegetables, such as apples and tomatoes.