The flu, a common seasonal illness, often increases heart rate. This physiological response is a natural part of the body’s efforts to combat the infection. Understanding this connection helps individuals recognize what is typical during illness and when medical evaluation might be needed. This article explores the mechanisms behind this phenomenon and offers guidance on managing your health during a flu infection.
Why the Flu Raises Heart Rate
When the influenza virus infects the body, it triggers a complex immune response that can lead to an elevated heart rate. The body’s defense mechanisms release various inflammatory markers and cytokines to fight the infection. This widespread inflammation can cause blood vessels to expand, signaling the brain to increase heart rate and blood flow to affected areas. The heart works harder to pump oxygen and immune cells throughout the body to combat the illness.
A significant factor contributing to a faster heartbeat during the flu is fever. As body temperature rises, the metabolic rate increases, demanding more oxygen delivery to tissues. Research indicates that for every 1 degree Celsius (1.8 degrees Fahrenheit) increase in body temperature, heart rate typically rises by approximately 8.5 to 10 beats per minute (bpm). This physiological adjustment helps maintain adequate blood circulation and tissue perfusion during febrile states.
Dehydration, common during illness due to reduced fluid intake, vomiting, or diarrhea, also contributes to an elevated heart rate. When the body is low on fluids, blood volume decreases, requiring the heart to pump faster to deliver oxygenated blood to organs and tissues. The overall stress from fighting the flu, including increased metabolic demand, can activate the sympathetic nervous system, further increasing heart rate.
Typical Heart Rate Responses During Illness
An increased heart rate during an illness like the flu is often a typical and temporary response as the body works to recover. For most adults, a normal resting heart rate ranges from 60 to 100 beats per minute (bpm). Oura data suggests that during flu or fever, the average heart rate can increase by about 8.5 bpm from baseline.
While an elevated heart rate can be unsettling, it often indicates the immune system is actively responding to the infection. The heart rate typically returns to its normal resting range once symptoms improve and the body recovers.
When to Seek Medical Attention
While a temporary increase in heart rate during the flu is common, certain signs warrant immediate medical evaluation. If your heart rate consistently remains above 100-120 beats per minute at rest, or if it feels unusually fast or irregular, it is important to consult a healthcare professional. An unusually high resting heart rate could indicate an underlying condition like atrial fibrillation.
Be aware of other symptoms that, when combined with an elevated heart rate, signal a need for urgent care. These include chest pain or pressure, shortness of breath, significant dizziness or lightheadedness, and fainting spells. Severe fatigue or weakness beyond typical flu symptoms, blue lips or face, confusion, or a fever not controlled by medication also require prompt medical attention.
Individuals with pre-existing heart conditions, such as heart disease, heart failure, or arrhythmias, are at a higher risk for serious flu complications. For these individuals, the flu can exacerbate existing symptoms and potentially lead to more severe outcomes like heart attacks or strokes. Prompt medical consultation is especially important if you have a heart condition and develop flu-like symptoms. Do not attempt to self-diagnose; always seek professional medical advice if you have concerns about your heart rate or flu symptoms.
Caring for Your Heart During Flu
Supporting your overall health during a flu infection can indirectly help your heart. Adequate rest is important for recovery, allowing your body to conserve energy and focus on fighting the virus. Staying well-hydrated by drinking plenty of water and clear fluids is also beneficial, as dehydration can place additional strain on the heart. Avoiding caffeinated beverages or other stimulants can also help prevent further heart rate elevation.
Avoiding strenuous physical activity is generally recommended when you have the flu, especially if you have a fever. Exercising with a fever can worsen the illness and may even be associated with heart inflammation. If symptoms are mild and above the neck, light activity like walking might be considered, but rest is advisable if symptoms include fever, body aches, or chest congestion. Following medical advice for symptom management, such as using fever-reducing medication, can also support your body’s recovery and help manage heart rate.