Most experts agree that “man flu” is a made-up term. Colds and flu affect both sexes, and science is undecided about whether a man’s symptoms are worse. But some research contains hints: A 2016 study in the journal Nature Communications, for example, concluded that viruses have evolved to be less harmful in women. In addition, Canadian research in 2009 suggested that women have stronger immune systems because of the hormone estrogen, and a 2017 theory advanced by a Canadian doctor supported the idea of an “immunity gap,” pointing out that testosterone suppresses the immune system, while a female’s estradiol hormone actually protects it. But more research is clearly needed before we can accept that "man flu" really exists.
In support of "man flu":
- The 2017 study by Dr. Kyle Sue pointed out that men are hospitalized more frequently with flu, and that American men are more likely to die from the flu than American women -- but underlying factors need to be factored in.
- A 2016 study published in American Journal of Physiology-Lung Cellular and Molecular Physiology found that a flu virus gets worse as the virus replicates itself. A woman’s estrogen reduces flu virus replication in nasal cells, the study found.
- Neuroscientist and author Amanda Ellison believes that flu symptoms may actually make men feel worse because the preoptic nucleus is twice as large in men, allowing for higher temperature responses when under viral attack.