© Polina Tankilevitch
October 9, 2026
Marianne Waldenfels
Just when the worst of the stress is over, your throat feels scratchy and your nose starts running. Coincidence? Unusual virus experiments and a new study reveal why stress may make us more susceptible to colds — and why it's not just about how much stress we experience.
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It was an unusual experiment: researchers administered cold viruses directly into the noses of nearly 400 healthy people and then waited to see who would get sick. The exposure took place under controlled conditions — yet the results were surprisingly varied. Of the participants who were under little stress, 27 percent fell ill, compared to 47 percent of those under particularly high levels of stress.
What made the difference? Why did the virus apparently find it easier to take hold in some people than in others? The researchers uncovered a connection that continues to raise questions to this day: Psychological stress appears to influence not only how we feel, but also how susceptible our bodies are to pathogens.
More than three decades later, scientists are still grappling with this question. A new study from 2026 suggests that it's not solely about the pressures we face — what may also matter is how we experience them.
Two people can go through the same difficult situation and react to it in completely different ways. What weighs on one person for days barely affects another. For the immune system, this difference could be significant.
This is suggested by a Journal of Health Psychology study published in June 2026. Researchers at Rutgers University analyzed data from 213 healthy adults who had taken part in a controlled cold virus experiment.
Before being exposed to the virus, participants reported which stressful events they had experienced and how stressed they felt. They were then given a cold virus and medically monitored throughout a quarantine period.
The analysis revealed that among people who had experienced a particularly large number of negative life events, higher perceived stress was associated with more severe cold symptoms. Personal stress perception may therefore play a role in determining how the body responds to a pathogen.
The experiment, published in 1991 in the New England Journal of Medicine published, yielded a second remarkable finding. The researchers looked not only at who developed cold symptoms, but also at which participants showed actual evidence of infection.
Among those under little stress, the figure was around 74 percent, compared to roughly 90 percent among those under particularly high levels of stress. The key difference was therefore already apparent at the point of infection — not just at the stage of symptoms.
The researchers accounted for potential confounding factors such as age, sleep, smoking, alcohol consumption, and physical activity. The association between stress and cold risk held firm.
The experiment thus provided an early indication that stress can increase susceptibility to respiratory infections. At the time, the scientists could not yet explain exactly why — later studies shed light on a possible mechanism.
When people are under prolonged pressure, the activity of certain hormones changes as well. One of these is cortisol. Often called the stress hormone, it actually performs numerous important functions in the body — among them, helping to regulate inflammatory responses.
Under normal circumstances, cortisol keeps the immune system from overreacting during an infection. As vital as fighting off pathogens is, an excessively strong inflammatory response can itself cause harm. Under persistent stress, this regulation may break down.
This was investigated by researchers in two experiments, the results of which were published in 2012 in the journal PNAS published.
In the first study, 276 healthy adults were deliberately exposed to rhinoviruses. The scientists had previously recorded whether the participants had experienced prolonged, severe stress.
A pattern emerged: in chronically stressed individuals, certain immune cells were less sensitive to the regulatory effects of cortisol. This reduced sensitivity was in turn associated with a higher risk of catching a cold.
In a second experiment involving 79 people, the researchers examined how the nasal mucosa responded after exposure to the virus. In infected individuals whose immune cells were less responsive to cortisol, stronger pro-inflammatory responses were observed.
Chronic stress, then, does not simply weaken the immune system. It may also disrupt its regulation, making inflammatory responses harder to keep in check.
This is particularly relevant when it comes to colds. A blocked nose, swollen mucous membranes, and a sore throat are partly the result of the inflammatory response the body mounts against the infection.
Whether targeted stress management can reduce the risk of catching a cold has so far been less thoroughly studied. What is clear, however, is that it is above all chronic stress that is problematic. A single hectic workday is not enough to bring on a cold.
These virus experiments show that psychological stress is far more than just a matter of wellbeing. Sustained pressure may also take a toll on the body's immune defenses.
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