The One Thing You Should Never, Ever Do When You Have a Cold, According to an Immunologist

You may feel more under the weather this time of year, and there’s a reason for that: According to the Centers for Disease Control and Prevention, cold and flu season is underway. The season began at the beginning of October, with peak numbers set to occur from December to February.

“The cold season tends to peak during the fall and winter months for several reasons, and it’s not solely due to the drop in temperature,” explains Dr. Ebru Karpuzoglu, MSc. Ph.D., immunologist and Adjunct Faculty at the University of Georgia, and Chief Scientific Director at AveSeena.

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But why? Mostly because the colder months force us indoors. “One primary factor is that people spend more time indoors with others, increasing close contact and the likelihood of virus transmission,” says Dr. Karpuzoglu. “In these enclosed spaces, ventilation is often poorer, and this allows respiratory droplets, which contain cold viruses like rhinoviruses and coronaviruses, to circulate and infect more people.”

Additionally, she adds that the cold air outside can irritate and dry out the mucous membranes in your nose, which are part of the body’s natural defense system.

“When these membranes become dry, they are less effective at trapping and expelling viruses,” says Dr. Karpuzoglu. “Studies have shown that cold viruses thrive in low-humidity conditions. During winter, indoor heating systems reduce humidity levels, creating an environment where viruses can survive longer in the air and on surfaces.”

A study published in Proceedings of the National Academy of Sciences showed that low humidity increases the airborne transmission of viruses, which is why cold and flu cases spike in colder months.

Another contributing factor? Your immune system may be weaker in colder temperatures due to reduced sunlight exposure, which can lead to lower vitamin D levels–crucial for immune function.

A study in Biomolecules found that vitamin D plays a role in activating immune defenses, and lower levels may reduce your body’s ability to fight off infections, making you more susceptible to catching colds during this time of year.

Related: Wait, Is It Normal to Get a Cold Every Month?

What Is a Cold?

A cold is a viral infection that affects the upper respiratory tract, including the nose, throat, sinuses, and larynx.

“It is typically caused by rhinoviruses, but other viruses, such as coronaviruses and adenoviruses, can also be responsible,” says Dr. Karpuzoglu. “These viruses are highly contagious and are primarily spread through respiratory droplets when an infected person coughs, sneezes, or talks. Cold viruses can also survive on surfaces for hours, making transmission possible through hand-to-surface contact followed by touching the face.”

Typical symptoms of a cold include a sore throat, runny or stuffy nose, sneezing, coughing, mild headaches, and sometimes low-grade fever.

“Unlike the flu, which can cause more severe symptoms such as high fever and body aches, colds usually result in milder discomfort,” adds Dr. Karpuzoglu. “The onset of symptoms occurs 1 to 3 days after exposure to the virus. Most colds resolve on their own within 7 to 10 days, although some symptoms, such as a lingering cough, can persist for up to two weeks.”

Related: The One Habit Doctors Are Begging You to Break ASAP If You Don’t Want to Get Sick This Fall

The One Thing You Should Never, Ever Do When You Have a Cold

According to Dr. Karpuzoglu, the one thing you should never do when you have a cold is push yourself to exercise strenuously or overexert your body.

“While mild activity like walking can help clear nasal passages and increase circulation, intense physical exertion, such as running or heavy lifting, can have the opposite effect on your immune system,” says Dr. Karpuzoglu. “When you’re sick, your body is already using energy and resources to fight off the infection. Pushing yourself to exercise intensely diverts these resources away from your immune response and towards muscle repair, leaving your body less equipped to handle the virus.”

A study in the European Journal of Applied Physiology found that intense exercise during a viral infection can prolong recovery time and increase susceptibility to complications like bronchitis or pneumonia. And stress can weaken your immune response, making it harder to recover from a cold. Studies show that chronic stress can suppress the body’s natural defenses, increasing the duration and severity of cold symptoms.

Related: What Do I Have: Is It a Cold, or the Flu?

“Moreover, vigorous exercise can increase the release of stress hormones such as cortisol, which can suppress immune function when elevated for prolonged periods. This is especially true when your body is already compromised due to illness,” adds Dr. Karpuzoglu. “Overexertion can also lead to dehydration, which exacerbates symptoms like a sore throat and congestion, making you feel worse.”

Instead of engaging in strenuous exercise, Dr. Karpuzoglu recommends that you opt for more restorative practices, such as yoga, gentle stretching, or short walks.

“These activities allow your body to continue moving without overwhelming your immune system, and they can help reduce inflammation and promote better circulation—key components of recovery,” she says. “Listen to your body and prioritize rest, hydration, and proper nutrition while your immune system fights off the cold.”

The bottom line: while it’s tempting to power through a cold and stay productive, one of the most important aspects of cold recovery is self-care and giving your body the time it needs to heal. 

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Sources

• Dr. Ebru Karpuzoglu, MSc. PhD, immunologist and Adjunct Faculty at the University of Georgia, as well as Chief Scientific Director at AveSeena