Should You Exercise When You Have the Flu?

Exercise can make you feel good and help keep you healthy, but a bout of the flu can sideline you — and fast. The flu is a respiratory illness often accompanied by congestion and trouble breathing.

Under these conditions, you generally shouldn't exercise or do anything that makes you breathe hard. If your flu symptoms are mild, use common sense when it comes to exercise. Don't push yourself too hard so you can give your body time to heal. If your symptoms are severe or you have a compromised immune system, see a medical professional for treatment and to discuss exercise options.

Influenza is caused by a virus that can cause fevers, stuffy nose, coughs, chills, sore throats and muscle aches, among other things, according to Harvard Health Publishing. While some of the symptoms resemble those of the common cold, the flu is generally more intense, makes you feel worse and often shows up suddenly.

If you experience nausea or diarrhea, you probably don't have the flu but have picked up a stomach virus — the "stomach flu" can make you miserable but isn't technically influenza.

The flu can be confirmed by a nasal swab at a doctor's office, according to the Centers for Disease Control and Prevention (CDC). And if you have flu-like symptoms after getting the flu shot, it's not the flu (that's a myth). You can (and should!) work out after getting the flu shot.

If you have a fever, cough, sore throat, runny or stuffy nose, body aches, headache, chills and/or fatigue, it might be time to see the doctor. You may or may not have the flu, and a doctor will diagnose you accordingly.

It's important to know if you have the flu or another contagious virus to limit your ability to spread it to others (aka, to know if you need to avoid the gym), but generally, most people can recover from the flu without medical help.

However, if you're over 65, are pregnant or have other complications, including severe symptoms, it's a smart idea to seek medical help, according to UCSF Health.

While it's true that exercise boosts immunity, once you're already sick, it's not going to help. And the idea that working out can help you "sweat out" an illness is a myth, according to NYU Langone Health.

You've likely heard that as long as your symptoms are "above the neck" (sneezing, runny nose, light cough), it's OK to exercise, and that's generally true, but you might still want to take the intensity down a notch, according to the Mayo Clinic.

Below-the-neck symptoms (a hacking cough, body aches, feeling dizzy and fever) are signals from your body that it needs to focus on healing and it's time to skip the workout.

You shouldn't exercise if you have a fever, which is a common symptom of the flu, per the Mayo Clinic. Your heart rate becomes elevated with a fever, and exercise can put too much strain on your heart. In some cases it can lead to heart failure.

You also have a higher risk of becoming dehydrated when you have a fever, and exercising exacerbates that risk. Fever indicates your body is working hard to overcome the flu virus, and the best thing you can do is rest and let your body heal.

Even if your symptoms are mild and you don't have a fever, if you suspect you have the flu or have been diagnosed with the flu, don't work out with other people.

The flu is a highly contagious illness that's passed directly between people or by touching a contaminated surface, so stay home when you're sick to avoid spreading your germs to other people. You can leave flu germs on workout equipment that other people can pick up if the equipment is not wiped down and sanitized, even six or seven days after getting the flu.

You can exercise if you have a cold, according to Harvard Health Publishing, although you may want to cut your workout in half. If you have the flu, you shouldn't exercise with the same intensity as when you're well. And if you have a fever, wait until it's gone before you hit the gym.

If your symptoms are mild, stick to gentle to moderate exercises if you just can't give up a workout. Consider going for a low-intensity walk or doing a restorative yoga session.

When you are over the flu, return to a regular exercise routine gradually to give your immune system a chance to build back up. If you had a fever, you should wait a couple of days after it breaks before doing any exercise, according to NYU Langone.

And per Harvard Health Publishing, you want your first workout to be low enough in intensity so that you don't get out of breath.

Don't expect to be able to do your old exercise routine right away — it might take a couple of weeks to get back into the swing of things.

To avoid catching the flu, think about working out during less popular hours at your gym during flu season and wipe equipment before using (and definitely after), per the University of California Irvine.

But don't skip working out, especially during flu season. Regularly getting up to 45 minutes of moderate intensity exercise supports your immune system, according to a 2020 article in ‌Exercise Immunology Review.‌