Why Do I Have an Elevated Heart Rate When I'm Sick and How to Handle It

When you’re sick, you likely spend more time relaxing in bed, allowing your body to rest. So, if you have an elevated heart rate when you’re sick, you may be understandably perplexed. However, a high heart rate when sick is not just normal; it’s also a sign that your immune system is doing its job.

Here, we’ll discuss why you may have a fast heart rate while sick, along with signs that you should seek additional medical assistance. 

Does Your Heart Rate Increase When Sick?

Yes, heart rate tends to increase when you’re sick. This happens because your immune system is working harder than usual to rid your body of the virus, causing your heart to pump more oxygen-filled blood throughout the body. It can also occur if you develop a fever, as an elevated body temperature causes the heart to beat faster.¹

To understand if your heart rate is elevated, you need to know the typical resting heart rate for your demographic. The normal resting heart rate range is 60 to 100 beats per minute, although most healthy adults have a rate of 55 to 85 beats per minute.²

You can measure your heart rate at home by:³

• Sitting in a comfortable position for a few minutes, making sure that you haven’t just exercised or consumed caffeine. If you’re feeling stressed out, it’s also not the best time to take your heart rate.
• Press the pads of your pointer and middle fingers against the side of your neck, right under the jawline, or on the inside of your wrist.
• Using a stopwatch or timer, count how many beats you feel for 15 seconds.
• Multiply the number of beats by four.
• Repeat this process three times, add all three numbers together, and divide the total by three.
• This gives you an accurate heart rate measurement.

Many of us associate a rapid heart rate with stress, anxiety, or various physical health problems, like low blood pressure and low blood sugar.⁴ However, if you experience a resting heart rate of 120 when sick, it may be due to the infection. Monitor your heart rate as you recover from the infection, and if it remains elevated at rest or you develop severe symptoms, contact your physician.

If you’re waiting to monitor your heart rate when your body’s not fighting an infection, you may wonder: How long does a cold last? Usually, cold symptoms go away within a week. If your symptoms persist longer than seven days, you should give your doctor a call, as you may need professional medical care to make a full recovery.⁵

Does Fever Increase Heart Rate?

So, why does the heart rate increase when sick? A fever is often the culprit. Fevers increase your body temperature, which leads to an elevated heart rate.¹

It’s widely accepted that a fever will increase heart rate. So, if your fever is accompanied by a high resting heart rate, you don’t necessarily need to seek urgent medical care. However, if your fever exceeds 104°F or is accompanied by severe symptoms, like confusion or loss of consciousness, you should contact your doctor right away.⁶

What Else Can Affect My Heart Rate?

Aside from a viral infection, many different factors can affect your heart rate, including exercise, body temperature, emotional states, dehydration, sleep, and certain medications.

• Exercise

Exercise can impact your heart rate in multiple ways. For one, your heart rate increases when you exercise. This occurs as your muscles require more oxygen to continue working, making your heart pump more blood throughout the body.

Additionally, people who exercise regularly tend to have a lower resting heart rate. This is because frequent aerobic exercise strengthens the heart muscle, causing it to pump more blood each time it beats. As a result, the heart doesn’t need to beat as often to keep blood circulating throughout the body.⁷

• Body temperature

Increased body temperature is directly linked to increased heart rate. This results from your body’s natural efforts to cool itself down by dilating, or widening, your blood vessels. When your blood vessels widen, your heart must beat faster to pump blood throughout your body.

This is why cold and flu symptoms may include an elevated heart rate for individuals who develop a fever.

• Emotional states

Certain emotional states, like stress, anxiety, anger, and panic, lead to an increased heart rate. This occurs when an emotion triggers your body’s “fight or flight” response, which stimulates the release of stress hormones. These hormones tell your heart to beat faster to pump more blood, preparing your body for an emergency situation, or “fight”.

Unfortunately, most modern stressors don’t benefit from this physiological process, and chronic stress can elevate your risk of high blood pressure and heart disease, among other health conditions.⁸

• Dehydration

Dehydration reduces the amount of blood pumping through your body (called blood volume). To make up for this decline and ensure your body is supplied with enough oxygen, your heart will start beating faster.⁹

• Sleep

Your quality of sleep can affect your heart rate. Getting seven to nine hours of high-quality sleep each night can help regulate your heart rate and preserve your heart health. On the other hand, individuals who have sleep problems (like frequent nightmares, waking up throughout the night, and sleep apnea) are more likely to have compromised cardiovascular health, which can lead to heart issues.¹⁰

• Certain medications

A range of medications can impact your heart rate, including asthma medication, cold medication, stimulants, and certain antidepressants. This is one reason why it’s important to always take medications as directed and contact your doctor if you experience side effects.

How to Lower Your Heart Rate When You’re Sick

As you consider common and uncommon flu symptoms, you may discover that being sick has elevated your heart rate. Now, how can you lower a fast heart rate when sick? Here are a few strategies:

• Stay hydrated by drinking plenty of fluids, like water, juice, and tea. Sickness causes your body to lose fluids more rapidly than usual, increasing the likelihood of dehydration. As we discussed in the previous section, being dehydrated leads to a higher heart rate.
• Avoid overheating by wearing breathable clothing and removing excess blankets. If you develop a fever, turn on a fan, open a window, and take a lukewarm bath or shower.
• Steer clear of common stimulants, like coffee and caffeinated tea.¹¹   
• Try stress-relieving strategies, like deep breathing, meditation, and journaling.¹²

Follow the tips listed above to avoid a heightened heartbeat when sick. You can also follow expert-approved cold and flu prevention tips to stay healthy before sickness strikes.

When to Seek for Additional Medical Help

If you experience a higher heart rate when sick, closely monitor your symptoms and seek additional medical help if:

• You have a fever over 104°F or that’s accompanied by severe symptoms, including:⁶
• Confusion
• Loss of consciousness
• Shortness of breath
• Chest pain
• Chest palpitations
• Dizziness or fainting
• Your fever gets worse or lasts more than three days
• Your resting heart rate remains at over 100 beats per minute, even after drinking plenty of fluids and resting your body.

While your heart rate does go up when you’re sick, it’s crucial to keep a close eye on your symptoms and seek prompt medical care if they become concerning.

Resources

1. Heal C, Harvey A, Brown S, Rowland AG, Roland D. The association between temperature, heart rate, and respiratory rate in children aged under 16 years attending urgent and emergency care settings. European Journal of Emergency Medicine. 2022;Publish Ahead of Print(6). doi:https://doi.org/10.1097/mej.0000000000000951
2. What your heart rate is telling you - Harvard Health. Harvard Health. Published August 30, 2020. https://www.health.harvard.edu/heart-health/what-your-heart-rate-is-telling-you
3. Romero J. How to Check Your Heart Rate. Mass General Brigham. Published December 13, 2022.