When you are feeling unwell, it is common to notice your heart beating faster than usual. This experience can be unsettling, but an elevated heart rate during illness is often a normal physiological response. The body works harder to combat an infection or recover from sickness, and this increased effort frequently leads to a temporary rise in heart rate. Understanding why this happens can help clarify what is a typical reaction and when it might signal a more serious concern.
How Illness Affects Heart Rate
When illness strikes, your body initiates a complex series of responses to fight off pathogens and promote healing. This intense internal activity places additional demands on your cardiovascular system, leading the heart to pump more frequently.
One significant factor contributing to an increased heart rate is fever, a common symptom of many infections. As body temperature rises, the metabolic rate increases, requiring more oxygen delivery to tissues. For every 1.8°F (1°C) increase in body temperature, the heart rate typically rises by approximately 10 beats per minute.
The immune system’s activation also plays a role in speeding up the heart. When fighting infection, the body releases inflammatory mediators such as cytokines, signaling the heart to pump more blood. This process transports immune cells and proteins to the infection site. This response can also expand blood vessels, triggering signals to increase heart rate and blood flow.
Dehydration, a frequent companion to illness, further contributes to an elevated heart rate. When sick, especially with fever, vomiting, or diarrhea, your body loses fluids rapidly. This decrease in blood volume compels the heart to beat faster to circulate blood and deliver oxygen. Stress and anxiety can also trigger the body’s “fight-or-flight” response, releasing adrenaline and accelerating the heart.
Common Conditions That Speed Up Your Heart
Many common illnesses can lead to an elevated heart rate as the body mobilizes its defenses. Viral infections, such as the common cold or influenza (flu), can cause an increased heart rate. The flu, for instance, places stress on the body, affecting blood pressure and heart function, leading to a faster heartbeat.
Bacterial infections, including pneumonia, also trigger these responses, causing the heart to work harder. Conditions like COVID-19 have also been noted to cause an increased heart rate, particularly when accompanied by fever or other symptoms.
In more severe cases of infection, such as sepsis, a rapid heart rate is a common compensatory mechanism as the body tries to maintain adequate blood flow despite significant systemic stress.
When to Be Concerned About a Fast Heart Rate
While an elevated heart rate is often a normal part of being sick, there are specific signs that warrant medical attention. A normal resting heart rate for most adults ranges from 60 to 100 beats per minute. It becomes concerning if your heart rate remains persistently high, generally over 100 beats per minute at rest, even as other illness symptoms begin to subside.
Seek immediate medical care if a fast heart rate is accompanied by more severe symptoms. These include:
- Chest pain or discomfort, which could indicate strain on the heart.
- Severe shortness of breath or difficulty breathing.
- Dizziness, lightheadedness, or fainting spells, which may signal insufficient blood flow to the brain.
- Confusion or a significant change in mental state.
If you experience any of these symptoms, consult a healthcare professional.