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Running With a Cold: Is It Better to Exercise or Take a Break?

To Run or Not to Run when you feel sick?

You had planned to run those crucial 8 miles today as part of your training program, but you’re feeling under the weather. So, the question arises: should you go running with a cold?

It’s common for runners to feel anxious about missing a workout. The fear of losing progress, especially when training for a marathon, an Ironman, or another big event, can be overwhelming. Missing even a few days can feel like a setback that might jeopardize reaching the starting line or achieving your desired time.

However, it’s essential to prioritize your health. The following guidelines will help you determine when to rest and when it might be safe to continue running with a cold.

The most important rule to remember is: better safe than sorry.
Your performance won’t suffer from missing a day or even three days of training. On the contrary, listening to your body and allowing it the rest it needs can lead to better long-term results. Be smart, be patient, and your body will thank you.


Disclaimer: This post is not medical advice and is not intended to provide diagnosis or treatment for any medical conditions. Please consult a physician or other health care professional for your specific health care and/or medical needs or concerns.


The answer largely depends on your symptoms. Common cold symptoms like a sore throat, nasal congestion, and a mild cough may still allow for a run. A helpful guideline is the ‘neck check’ rule:

if your symptoms are above the neck, such as a runny nose or a mild headache, it’s generally safe to go for a run. However, it’s best to rest if your symptoms are below the neck, like chest congestion, a persistent cough, or an upset stomach.

If you’re uncertain about your symptoms, it’s safer to skip your run and consult a healthcare professional.
Running with a mild head cold can sometimes alleviate symptoms due to the release of adrenaline and endorphins, which might temporarily clear nasal congestion. However, if you have a fever, it’s essential to avoid running, as this can exacerbate your condition.

Running with a cold - The 'Neck Check' rule: if your symptoms are above the neck, such as a runny nose or a mild headache, it's generally safe to go for a run. However, it's best to rest if your symptoms are below the neck,

When feeling under the weather, it’s crucial to modify your training plan to accommodate your condition. This might mean reducing the speed and intensity of your workouts or adjusting your schedule by swapping easy training days with more intense ones. Cold symptoms can make breathing challenging, thereby limiting your ability to exercise.

If you’re feeling relatively well despite mild symptoms, consider the following adjustments:

  • Extend your warm-up: Spend extra time warming up to ease into your run more gradually.
  • Avoid intense workouts: Skip interval training and speed work, opting for a more relaxed pace instead.
  • Shorten your run: Aim for a shorter distance than usual to avoid overexertion.
  • Dress appropriately: Ensure you’re dressed according to the weather to stay comfortable and prevent further complications.

Remember, it’s more important to focus on the effort rather than the numbers on your watch, especially when you’re not feeling 100%. Using a heart rate monitor can help you maintain a safe and appropriate level of exertion by keeping track of your heart rate zone.

If you’re experiencing symptoms of the flu, such as muscle aches, fever, or significant weakness, do not run.
Engaging in physical activity while running a fever and experiencing pain is not only dangerous but can also exacerbate your illness, leading to a longer recovery period and more missed training days.

Illustration of a not-to-do sign with the text 'Don’t run when having the flu!
Avoid running with the flu!

A fever indicates that your body is fighting an infection, whether viral or bacterial. Running with a fever can cause your body to overheat, worsening symptoms and potentially posing immediate or long-term health risks. Additionally, exercise can temporarily weaken the immune system, particularly in the 20 hours following intense workouts, making you more susceptible to infections.

Running while sick with the flu diverts your body’s resources away from fighting the virus, slowing down your recovery. Therefore, it’s crucial to rest and allow your body to heal fully.

Remember, it typically takes at least 10 days to lose physical fitness, so missing a few days of training won’t have a significant impact.

The same precautions apply if you’ve had Covid-19. It’s vital to avoid running until all symptoms have resolved.

How Long Should I Wait After the Flu Before Returning to Running?

There’s no one-size-fits-all rule for when to resume running after recovering from the flu. The timeline can vary depending on the severity of your illness and your overall health.

Generally, if you experienced a mild case, you can consider returning to training at least 24 hours after you feel fully recovered and no longer have a fever.

However, it’s advisable to start with low-intensity workouts and closely monitor your body’s response to ensure a safe return to your routine.


Common Mistakes to Avoid:

➤ 1. Don’t Overcompensate for Missed Training

It’s tempting to make up for lost time, but avoid pushing yourself too hard too soon. After an illness, your immune system may still be vulnerable, and your body might not be ready for high-intensity workouts.
Start with easy sessions, gradually increasing the pace and distance after at least three days of slow and short runs.

➤ 2. Practice Patience

While missing training can be frustrating, it’s crucial to listen to your body and give it time to recover fully. Rushing back into intense workouts can prolong your recovery and potentially lead to further illness.
Patience will allow you to return to running sooner and in better health.

Setting realistic goals during your recovery period can help you manage your expectations and reduce anxiety.

➤ 3. Stop if You Feel Unwell During a Run

If you start feeling unwell while running, it’s best to stop or at least slow down and shorten your run. Listening to your body is key to preventing further illness or injury.

➤ 4. Returning to Group Training

If you usually train with a running group, consider running alone for a while as you recover.
Being in a group can sometimes lead to pushing yourself too hard due to competition or peer pressure. Running solo allows you to focus on your own pace and recovery without external pressures.


When you’re dealing with a cold or feeling unwell, it’s important to listen to your body and use common sense to determine whether you should slow down or take a rest day.

If you’re not up for running but still feel well enough for some light activity, consider gentle exercises like Pilates or yoga specifically tailored for runners. These activities allow you to move your body while providing the flexibility to stop if you start feeling worse. Prioritizing your well-being ensures a safer and quicker recovery.

A runner taking a moment to listen to their body, assessing whether to continue or stop running due to cold symptoms. The image emphasizes the importance of paying attention to physical cues when deciding whether to exercise while feeling unwell.
When deciding whether to run while feeling sick, you should also listen to your body and use common sense.

The immune system plays a critical role in protecting the body from infections, but running while sick can impact this system’s effectiveness.

  1. Temporary Immunosuppression: Intense exercise can temporarily suppress the immune system, especially when sick. This makes the body more susceptible to infections and can potentially worsen the current illness. The phenomenon known as the “open window” effect occurs after prolonged, intense exercise, during which the body’s immune defenses are lowered for some time.
  2. Inflammatory Response: Running can induce an inflammatory response in the body, which, when combined with the inflammation caused by an illness, can lead to increased symptoms such as muscle aches and joint pain.
  3. Delayed Recovery: By diverting energy and resources away from the immune system’s efforts to fight off an infection, running can prolong recovery times. The body needs rest to heal, and physical exertion can delay this process.
Illustration of immune response levels comparing a normal state, being sick without exercise, and being sick with exercise. Highlights the potential decrease in immune response when exercising while ill.
Immune Response Levels During Illness: Normal, Sick, and Sick with Exercise

The above diagram is based on the scientific article “The Compelling Link Between Physical Activity and the Body’s Defense System” by David C. Nieman and Laurel M. Wentz. It was published in the Journal of Sport and Health Science, Volume 8, Issue 3, May 2019, Pages 201-217. You can access the article here.

In conclusion, when you’re sick, running can further weaken your immune system, prolonging recovery. Prioritize rest and allow your body time to heal, especially if you have symptoms like chest congestion or fever.

Will running with a cold make it worse?

Running at a moderate pace is unlikely to worsen your illness or symptoms, but it won’t necessarily shorten the duration. One benefit of light exercise, like easy running, is that it can help break up congestion, especially if you’re well-hydrated. However, dehydration can exacerbate congestion, so drinking plenty of fluids is essential.

Is it bad to run when you have a sore throat?

According to the ‘neck check rule‘, if your symptoms are above the neck—such as a sore throat, runny or stuffy nose, or sneezing—it’s generally safe to go for a short, easy run. This can sometimes help, as physical activity may release epinephrine, a natural decongestant. However, pay attention to your body and stop running if you experience symptoms like dizziness, nausea, or excessive sweating.

Should I run with a chesty cough?

A chesty cough is below the neck, so following the ‘neck check rule’, you should avoid running, especially if accompanied by a fever or other symptoms like chest congestion or a productive cough. It’s best to rest until these symptoms resolve.

How long after exposure to the flu do symptoms appear?

Flu symptoms, including muscle aches, fever, and weakness, typically appear about two days after exposure to the virus, though they can range from 1 to 4 days. Some individuals may carry the flu virus without showing symptoms. Regardless, if you experience flu symptoms, do not run! It’s crucial to rest and recover fully before resuming physical activity.

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