Can being sick cause an irregular heartbeat? The link between illness and arrhythmia

October 1, 2025 •

5 min read

According to the National Institutes of Health, viral infections like the flu and COVID-19 can significantly increase the risk of an irregular heartbeat. This is because illness can put a strain on your cardiovascular system, leading to temporary but noticeable changes in your heart's rhythm. In this article, we'll explore the complex relationship between being sick and your heart's electrical system and explain why an irregular heartbeat is a potential side effect.

Quick Summary

Illnesses, especially those involving fever and inflammation, can cause temporary changes in heart rhythm by increasing cardiac workload and impacting the body's electrolyte balance. In more severe cases, a viral infection can directly affect the heart muscle, leading to more serious arrhythmias. It's often a domino effect where one physical stressor leads to another, all of which can influence your heartbeat.

Key Points

Illness Increases Cardiac Strain: When your body fights an infection, it increases its metabolic rate and core temperature (fever), causing your heart to pump faster to meet the body's increased demands.
Dehydration Affects Heart Rhythm: Illnesses causing fluid loss can lead to dehydration and an electrolyte imbalance, both of which can directly trigger heart palpitations or a faster heartbeat.
Inflammation Can Lead to Myocarditis: The body's inflammatory response to a virus can, in some cases, affect the heart muscle (myocarditis), which is a direct cause of potentially serious irregular heartbeats.
Certain Viruses Are More Risky: Viruses like influenza, COVID-19, and adenovirus have been specifically linked to a higher risk of arrhythmias due to their inflammatory effects on the heart.
Stress Complicates Diagnosis: The anxiety of being sick can cause symptoms similar to a true arrhythmia, making it important to differentiate between a stress-induced rapid heartbeat and a genuinely irregular rhythm.
Know When to Seek Medical Help: While mild palpitations during illness can be normal, symptoms like chest pain, fainting, or persistent irregular heartbeats should prompt immediate medical evaluation.

The Body's Response to Illness

When you get sick, your body initiates a complex response to fight off the infection, which places added stress on your entire system, including your heart. This can lead to a variety of cardiovascular effects, from a harmless, temporary increase in heart rate to more significant and concerning irregularities. The way your body mobilizes its resources to combat a virus or bacteria can directly influence the delicate electrical signals that regulate your heartbeat.

How Fever and Inflammation Affect Heart Rhythm

One of the most common responses to infection is a fever, which is the body's natural way of making itself a less hospitable environment for pathogens. As your body temperature rises, your heart rate increases to pump more oxygenated blood and immune cells to where they are needed. This higher demand can sometimes cause the heart to beat faster than normal, a condition known as tachycardia, and in some individuals, this can feel like a fluttering or pounding sensation in the chest.

Beyond fever, illness often triggers widespread inflammation. Cytokines, which are released during the immune response, can have a direct impact on the heart muscle and its electrical system. In some cases, this inflammation can directly lead to myocarditis, an inflammation of the heart muscle itself, which is a known cause of arrhythmias. Viruses like influenza and COVID-19 have been directly linked to this cardiac inflammation.

The Role of Dehydration and Electrolyte Imbalance

Many illnesses, particularly those involving vomiting, diarrhea, or a loss of appetite, can lead to dehydration. Dehydration decreases the volume of blood, forcing the heart to pump faster and work harder to circulate oxygen throughout the body. This increased workload can manifest as heart palpitations or a noticeably rapid heart rate. Furthermore, fluid loss can disrupt the body's delicate balance of electrolytes, such as potassium, sodium, and calcium, which are crucial for the proper electrical signaling of the heart. An imbalance in these minerals can directly trigger an irregular heartbeat.

Specific Viral Infections and Their Cardiac Effects

Certain viruses are more notorious than others for their ability to affect the heart and cause arrhythmias. It is important to be aware of these potential connections, as they can sometimes lead to more serious complications.

COVID-19: Since the onset of the pandemic, extensive research has shown a clear link between COVID-19 infection and an increased risk of atrial fibrillation and other arrhythmias. Inflammation triggered by the virus, as well as the stress it places on the cardiovascular system, can lead to new-onset heart rhythm problems.
Influenza: A severe case of the flu can cause widespread inflammation and low oxygen levels, both of which can aggravate pre-existing heart rhythm issues or trigger new ones. In rare but serious cases, influenza can even lead to myocarditis.
Adenovirus: Commonly associated with the common cold, certain adenoviruses have been shown to directly interfere with the heart's electrical communication, sometimes resulting in serious arrhythmias.
Coxsackievirus B: A major cause of viral myocarditis, this virus can alter the heart's electrical pathways, potentially causing ventricular arrhythmias and, in severe cases, sudden cardiac death.

How Pre-existing Conditions Increase Risk

For individuals with pre-existing heart conditions, the risk of an illness-induced irregular heartbeat is higher. Conditions such as heart failure, coronary artery disease, or a history of arrhythmias can make the heart more vulnerable to the added strain of an infection. The extra workload and inflammatory response can exacerbate an already weakened heart, making it more prone to an episode of arrhythmia.

Understanding the Difference: Anxiety vs. Arrhythmia

It can be difficult to distinguish between the physical sensations caused by anxiety during an illness and a true arrhythmia. Both can cause a rapid heart rate and a fluttering sensation. However, an arrhythmia, particularly one that is persistent or occurs with other symptoms like dizziness or chest pain, is a physical issue that needs medical attention. Stress and anxiety can trigger the release of adrenaline, which can cause a rapid but typically regular heartbeat. A true arrhythmia, like atrial fibrillation, involves erratic electrical signals, leading to an irregular rhythm.

When to See a Doctor

While it's normal for your heart rate to increase slightly when you have a fever, certain symptoms warrant a visit to a healthcare provider. You should seek medical attention if you experience any of the following alongside an irregular heartbeat:

Frequent or persistent irregular heartbeats
Chest pain or pressure
Dizziness, lightheadedness, or fainting
Shortness of breath
Fatigue or weakness unrelated to the general malaise of being sick

Management and Prevention

Managing an irregular heartbeat during illness often involves treating the underlying infection and supporting your body's recovery. This includes staying well-hydrated, resting, and following your doctor's recommendations. In cases where the irregular heartbeat is persistent or severe, further medical evaluation and treatment may be necessary. Preventive measures include staying up-to-date on vaccinations, practicing good hygiene, and managing any underlying health conditions. For those with pre-existing heart issues, it's crucial to be proactive and communicate any changes in heart rhythm to a healthcare provider.

Comparison of Common Illness-Related Triggers for Arrhythmia


Trigger	Mechanism	Common Resulting Arrhythmia	Severity	Risk Factors
Fever	Increased cardiac demand and metabolic rate	Tachycardia (fast heart rate), palpitations	Mild to Moderate	Pre-existing heart conditions
Inflammation	Immune response affecting heart muscle directly	Myocarditis, atrial fibrillation (AFib)	Moderate to Severe	Severe infections, chronic heart disease
Dehydration	Decreased blood volume, electrolyte imbalance	Tachycardia, palpitations, skipped beats	Mild to Moderate	Vomiting, diarrhea, poor fluid intake
Stress/Anxiety	Adrenaline release from fight-or-flight response	Rapid heart rate, palpitations, occasional skips	Mild to Moderate	High emotional distress, existing heart issues
Viral Myocarditis	Direct viral invasion and inflammation of heart muscle	Ventricular arrhythmias, AV block	Severe	Specific viral infections (e.g., Coxsackievirus, COVID-19)

Conclusion

Yes, being sick can absolutely cause an irregular heartbeat. It's often a direct result of the body's natural response to infection, involving factors like fever, inflammation, and dehydration. While many of these instances are temporary and harmless, they serve as a reminder of the interconnectedness of our body's systems. For those with underlying heart conditions or who experience persistent or severe symptoms, the risk of serious complications is higher. Understanding the link between illness and heart rhythm is key to knowing when a temporary inconvenience might be a sign to seek further medical evaluation. For authoritative information on heart arrhythmias and related conditions, you can visit the American Heart Association website.

Frequently Asked Questions

Yes, a high fever can cause an irregular heartbeat, primarily by increasing your overall heart rate. As your body temperature rises, your heart works harder to pump blood, which can sometimes result in palpitations or a temporarily rapid, but generally regular, heartbeat. If you have pre-existing heart conditions, the risk of a more noticeable irregular rhythm increases.

While an irregular heartbeat during illness is often temporary, you should be concerned if it is persistent, frequent, or accompanied by symptoms like chest pain, fainting, or severe shortness of breath. A doctor can perform diagnostic tests, such as an EKG, to determine the underlying cause and severity.

No, not all viruses cause heart problems, and even for those that can, the vast majority of cases do not lead to severe complications. However, some viruses, like influenza and the one that causes COVID-19, are known to have potential cardiac effects, particularly in severe infections or in individuals with pre-existing heart conditions.

Yes, dehydration is a very common cause of heart palpitations during an illness. When you lose fluids through vomiting or fever, your blood volume decreases, causing your heart to work harder. This, along with an imbalance of electrolytes vital for heart function, can lead to a fluttering or pounding sensation in your chest.

It is possible, though not common, for an irregular heartbeat to linger after the main illness has passed. If your symptoms continue for several days or weeks after recovering, it's important to see a doctor. In rare cases, a virus can cause lingering inflammation of the heart muscle or other long-term effects.

To reduce the risk of an irregular heartbeat, focus on staying well-hydrated, especially if you have a fever or are experiencing fluid loss. Rest is also crucial. Avoid stimulants like caffeine and excessive alcohol. If you have a known heart condition, follow your doctor's guidance closely.

While both can cause a rapid heart rate, a panic attack is typically triggered by extreme stress or anxiety and results in a rapid but regular heartbeat. A true arrhythmia, like atrial fibrillation, involves an erratic and irregular rhythm due to a physical electrical issue in the heart. If in doubt, medical evaluation is the safest course of action.