It happens every year. As the days grow shorter and temperatures drop, the flu season begins. Influenza is so common that it’s often dismissed as “just a passing virus.” And in most cases, it is caused by a virus that many recover from without specific treatment. But the experience of catching the flu appears to differ between men and women.
A recent and intriguing medical study has revealed that men may actually suffer more severely from the flu than women. This finding challenges the common stereotype of “man flu,” where men are accused of exaggerating mild symptoms. According to the study, the male immune system is less effective at fighting off the flu virus compared to the female immune system, supporting a long-standing belief often dismissed as a myth by health experts.
The study, published in a special holiday edition of a respected American medical journal, aimed to explore the accuracy of the term “man flu,” often used humorously to imply that men overreact to colds or flu.
Dr. Kyle Sue, an assistant professor at Memorial University in Newfoundland, Canada, who led the study, noted:
"Although the term is commonly used (especially in the UK), no scientific review had been conducted to determine whether it’s valid."
After reviewing various scientific papers, Dr. Sue found multiple lines of evidence suggesting that men may indeed have a weaker immune response to respiratory viruses, leading to more severe symptoms — and even a higher risk of death — compared to women.
For example, a 2008 study found that women generate a stronger immune response to the flu vaccine, producing higher levels of antibodies against the virus strains. Additional studies in Hong Kong and the United States showed that men were more likely to be hospitalized or die from the flu than women.
In his article, Dr. Sue writes:
“The idea of ‘man flu,’ as it's commonly known, may not be a myth. Men may not be exaggerating but rather experiencing a biologically weaker response to respiratory viruses, which can lead to more severe illness and higher mortality.”
The reason behind men’s weaker immune responses isn’t entirely clear, but hormones may play a significant role. For instance, estrogen, a hormone more prevalent in women, seems to offer protective effects against the flu. A 2016 study injected human nasal cells from both male and female donors with the flu virus. Results showed that estrogen reduced the viral levels in female cells, but had no effect in male cells.
Conversely, the male hormone testosterone may suppress immune function, reducing the body’s ability to fight off viruses like influenza.
That said, more research is needed, especially because many studies don’t fully account for variables like smoking, access to preventive healthcare, or lifestyle factors, all of which can influence flu outcomes. Moreover, there is limited research that breaks down respiratory virus data by sex.
Some researchers even speculate that this difference in immune response might have evolutionary roots. Dr. Sue suggests that in early human history, the benefits of testosterone — like increased muscle mass and physical strength — may have outweighed the costs of weaker immunity, though more research is needed to explore this theory further.
