Should You Run While Sick? Running With COVID, Flu, RSV, and a Common Cold
Should You Run While Sick?
A question I’ve gotten several times. Keep in mind, I’m no doctor. I’ve had my fair share of times I was sick and wish I had taken a few extra days off.
I wish running while sick had one easy answer because runners love a rule. “Above the neck is fine.” “No fever means go.” “Sweat it out.” I have heard all of it, and I have also been the person bargaining with myself because a workout was on the schedule and my body was clearly asking for rest.
The short answer is: sometimes you can run while sick, but the run should change. Sometimes the smartest training decision is skipping the run. There is a big difference between running with a common cold and running with the flu, COVID, RSV, fever, chest tightness, wheezing, or body aches.
Quick Answer: Should You Run While Sick?
First, find out what you have. That is kind of essential here. You can usually do easy, short activity if your symptoms are mild, above the neck, and you do not have a fever. Think runny nose, mild nasal congestion, sneezing, or a minor sore throat. Mayo Clinic says mild to moderate physical activity is usually OK with a common cold and no fever, but it also recommends reducing intensity and duration. Don’t be afraid to walk even if “you have never had to walk before”.
Do not run if you have fever, fatigue, widespread body aches, chest congestion, a hard cough, stomach issues, trouble breathing, chest pain, dizziness, or symptoms that are getting worse. Mayo Clinic also says not to exercise with other people if you have COVID-19 or another contagious illness.
That means your “should I run while sick?” answer often looks like this:
- Mild cold, no fever: Short easy run or walk.
- Flu symptoms: Rest.
- COVID symptoms: Rest, isolate from others, and return gradually.
- RSV with wheezing, fever, chest symptoms, or breathing issues: Rest and consider medical advice.
- Fever: No run.
- Chest pain, shortness of breath, faintness, palpitations: No run and get medical care.
Keep in mind, a few days of rest never hurt anyone.
Running With a Common Cold
Running with a common cold is the one area where a short easy run can be fine. If your symptoms are all above the neck, like congestion, sneezing, or a mild sore throat, an easy run may help you feel less stuffed up for a bit. It is not a magic cure, and it is not a green light for intervals. Skip workouts and hard efforts, dial back your easy run because these are not the signs to run harder.
If I had a mild cold, I would ask myself:
- Can I breathe comfortably?
- Do I feel normal walking around the house?
- Do I have normal energy?
- Is my heart rate close to normal?
- Could I run alone without exposing anyone else?
If the answer is yes, then maybe an easy run. There is no need to do a hard effort, because that can and will set you back.
A good rule for running with a common cold: finish feeling better than when you started. If you start to feel worse, turn around. No one gets bonus fitness for making a cold linger.
Running With the Flu
Running with flu is different. The flu often comes on abruptly, and the CDC lists fever, aches, fatigue, weakness, headache, chills, and chest discomfort or cough as more common with flu than with a cold. From personal experience, I cannot emphasize enough that you should rest with the flu.
I learned this the hard way after getting the flu, and it affected my running for months. I wrote about it in The Flu: The Worst Sickness I’ve Ever Had, and how I came back too early and it took me months (almost a year) to feel better.
If you think you have the flu, skip the run. CDC says flu antivirals work best when started early, ideally within two days after symptoms begin, and they may make illness milder or shorter for some people. If you are high risk, very sick, or concerned, contact a healthcare provider.
Return to running after flu should be slow. Being fever-free for 24 hours is a baseline for getting back to normal activities, but training hard is not a normal activity. Start with walking, then short easy running, then regular easy mileage, then workouts once breathing, energy, appetite, and resting heart rate look normal again.
Running With COVID
Running with COVID deserves its own section because runners often want to know: “When can I run after COVID?” or “Can I run with mild COVID?”
Current CDC respiratory virus guidance says you can return to normal activities when, for at least 24 hours, symptoms are improving overall and you have been fever-free without fever-reducing medication. CDC also recommends extra precautions for the next five days, including cleaner air, hygiene, masking, distancing, or testing around others, because you may still be able to spread the virus. Don’t be a jerk and go to a race and spread it.
For running, I would be more conservative than “normal activities.” Maybe some light walking but not running. If you have COVID symptoms, skip the run until symptoms are clearly improving, fever is gone, and you can move around without unusual fatigue, chest tightness, dizziness, or breathing issues. If you are higher risk, CDC says COVID treatments must be started within 5 to 7 days after symptoms begin to be effective, so do not wait until day eight to ask about options.
The American College of Cardiology says athletes recovering from COVID-19 who have cardiopulmonary symptoms, including chest tightness, worsening exertional shortness of breath, palpitations, lightheadedness, or syncope, should have cardiac testing before return to play. It also says new cardiopulmonary symptoms after returning to exercise warrant testing.
That does not mean every runner needs every test after every mild case. It means chest symptoms are not something to run through.
I have had COVID affect training before. In my February Training: Illness Strikes Again post, COVID derailed a peak marathon month. I also wrote in my Los Angeles Marathon recap that getting COVID a month before the marathon affected my breathing. That is a long way of saying: returning is not always linear, even when you are fit.
Running With RSV
Most adult RSV cases are mild and look like a cold, but RSV can also include cough, fever, wheezing, and appetite changes. CDC says RSV can worsen asthma, COPD, and heart failure, and adults with severe RSV may need hospital care.
Running with RSV depends on symptoms. Mild congestion with no fever and no chest symptoms may fall into the same easy-run category as a mild cold. Wheezing, chest pressure, difficulty breathing, fever, or symptoms getting worse should be a full stop. CDC says adults should call a healthcare provider for difficulty breathing, trouble eating or drinking, chest pain or pressure, sudden dizziness or confusion, or worsening symptoms.
A runner with RSV should be especially careful with hard breathing in cold air, group runs, and workouts. Even when the worst symptoms pass, coughing and airway irritation can hang around. Give your lungs time.
Should You Race While Sick?
Most of us know the answer before we ask. We just want permission to ignore it because the race fee is gone, the hotel is booked, and the outfit is already chosen. In a recent newsletter, I wrote about paying for a race does not mean you need to run it.
If you have a mild cold and no fever, racing is a personal call, although I would still lower expectations and avoid exposing others. Seriously, don’t get others sick. If you have flu symptoms, COVID, RSV with chest symptoms, fever, body aches, vomiting, diarrhea, dizziness, or unusual shortness of breath, do not race.
Racing involves travel, crowds, stress, higher intensity, and often poor sleep. You can turn a seven-day illness into a several-week hole. I have raced after illness enough times to know that fitness does not vanish after a few missed days, but when you force a timeline, come back too early, and don’t recover you may take several months to feel back to normal. You also should consider other racers: are you going to pass on your sickness to someone else?
What About Losing Fitness After Being Sick?
A few days off is not a crisis and you won’t lose fitness. I cannot emphasize that you do not lose fitness in a day or week. You may lose some with a straight month off, but it will come back. You do not lose a season from taking time off for the flu, COVID, RSV, or a rough cold. You can lose more training time by pretending you are fine when your body is still fighting something. Rest is training when the other option is digging a deeper hole.
I have had sickness mess with running, from the flu to possible long COVID symptoms to racing after COVID. I have also had races come together after illness when I gave myself enough time, like coming back through the spring instead of forcing every scheduled workout.
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Questions for you:
Have you ever run while sick?
What are your rules for running while sick?