How the flu can damage your heart

Exercising before you fully recover from the flu could cause myocarditis, a serious heart condition.

19 May 2006
by Amelia Keegan

It’s time for a reality check. Influenza, commonly known as flu, is a serious illness, which can kill. We’re not talking about bird flu or some rare Congo fever, we’re talking about the common disease that almost everyone has had more than once.

And because you’ve had the flu before, you’ve probably also heard the warnings: "No exercising when you have flu." That’s not just because you’re feeling tired and need to rest. There are serious complications that can follow from a bout of flu, or even a cold, that could threaten the health of your heart.

But why does a viral infection that causes a cough and fever have such a potentially serious effect on the heart? "When you have a fever, your heart has to work extra hard," explains Dr Gabe Mirkin on "Furthermore, some viruses that infect your nose and throat also infect your heart muscle. The combination of the extra work and an infected heart muscle could cause irregular heart beats."

Listen to your body

A few days after shaking off a nasty bout of flu, Elise Merry went hiking with her husband in Cape Town. After 20 minutes on a rather challenging mountain path, she began to feel breathless and experienced a strange flurry of heartbeats. Because Elise is a doctor, she realised that she should not press on, and needed to rest immediately. Luckily there was an access road nearby, and her husband was able to fetch her and drive her back to town to have a check-up in hospital. What Elise experienced was myocarditis, an inflammation of the heart muscle, and one of the potentially dangerous side effects of a viral infection.

Protect your heart

Myocarditis is most dangerous for people who already have heart problems, whether or not they are aware of them. But even for someone like Elise, a woman at the time in her late 30s with no history of any heart problems, it can be a potentially dangerous condition. At worst, it can lead to permanent heart failure, although many people recover completely and suffer no further ill effects.

The symptoms of myocarditis may be similar to a heart attack, including a severe pain in the chest, fatigue, shortness of breath and abnormal heart beats. There may also be swelling in the joints. If you feel any fluttering or other irregularity in your heartbeat, get to the doctor or emergency room so that you can be checked out.

To diagnose myocarditis the doctor will ask you about any recent viral infections or heart problems, and give you a number of tests that may include blood tests, an electrocardiogram, a chest X-ray and ultrasound. The patient may be treated with antibiotics if the doctor finds a bacterial infection, and lifestyle adjustments such as bedrest, avoiding salt, and diuretics to reduce fluid may be recommended.

If there is long-term damage, the doctor will assess whether treatments such as a pacemaker or blood-thinning medicine are needed. It’s vitally important not to resume an exercise programme until the doctor has given you the all-clear.

Myocarditis can be present without any symptoms at all, so even the fittest people shouldn't exercise vigorously when they have a viral infection, and they should ease back into it slowly after a cold or the flu. Myocarditis is not only associated with flu, but also with other viral infections such as rubella or polio.

The important thing is to be kind to your body and let yourself rest. Most importantly, always consult a medical professional if you're concerned about your health. 

How Clicks Clinics can help you during the flu season

Book an appointment for a flu vaccination at a Clicks Clinic by calling 0860 254 257 or visiting Clicks Clinics online. The good news is that most medical aids now cover the flu vaccination and sometimes even reward members. 

Take note that the following people cannot get vaccinated:

  • Babies younger than 6 months
  • Anyone allergic to eggs
  • Anyone who already has a fever
  • Anyone who has shown a past reaction to a vaccine



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