NHS GP Jeff Foster has weighed in on the long-running debate over whether 'man flu' is real, concluding that scientific evidence suggests men may experience worse symptoms and slower recovery from respiratory infections than women.
Dr Foster, an NHS GP Partner and Medical Director for Men's Health and TRT Specialist at Voy, said: "The honest answer about man flu? There's something in it."
Biological basis for worse symptoms
Research published in the British Medical Journal has suggested that men may experience more severe symptoms from respiratory viruses than women, partly due to differences in immune response. Women tend to have a faster, more aggressive initial immune reaction to viral infections, which may help clear the virus more quickly. Men's immune systems appear to respond differently, which can mean symptoms linger longer and feel more intense.
Dr Foster added: "That said, individual variation matters just as much as sex. Your age, baseline health, sleep quality, stress levels, and even your gut microbiome all influence how your immune system responds to a virus. Two people can be exposed to the same bug and have completely different experiences. That's not weakness - it's biology."
The BMJ research highlights that oestrogen acts as a natural immune booster, helping female cells resist viral replication, whereas testosterone can have an immunosuppressive effect that lowers a man's initial antibody response. Data also shows that adult men experience higher rates of flu-related hospital admissions and take longer to recover from sinus infections.
Distinguishing cold from flu
A 2013 study titled "Systems analysis of sex differences reveals an immunosuppressive role for testosterone in the response to influenza vaccination" shows marked differences between the sexes in their immune response to infections and vaccination. It adds: "Females have generally more robust immune responses than males for reasons that are not well-understood."
Dr Foster explained how to tell a cold from flu: "The common cold and influenza are caused by entirely different viruses, and the distinction matters. A cold tends to build gradually: a sore throat first, then congestion, a runny nose, mild fatigue. Flu is different. It hits fast, often within hours, with high fever, significant muscle aches, profound tiredness, and a dry cough. If you feel fine at breakfast and floored by lunchtime, that's more likely to be flu."
When to seek medical attention
Dr Foster listed symptoms that should never be disregarded: persistent chest pain or pressure, severe shortness of breath or inability to finish sentences without pausing, a temperature climbing beyond normal levels and failing to respond to medication, persistent confusion or difficulty waking up, and symptoms that improve then worsen again.
He said: "All these above symptoms warrant medical attention, not another day under a duvet." For most people, he recommends "rest, fluids, and paracetamol or ibuprofen to manage fever and discomfort". He added: "Stay home if you can. Autumn and winter viruses spread quickly, and the most effective thing you can do for the people around you is to not share what you've got. Man flu may be embellished, but the virus underneath it is very much real."
