A little known cause of man-flu?

The middle-aged male cashier who served me Sainsbury's this afternoon was plainly under weather. After laughing off his symptoms with a self-deprecatory diagnosis of man-flu, he then said that it was nonetheless a real condition. His special pleading then broke down, because he put his plight down to excess oestrogen!
Cue hilarity from self and two women ahead of me in the queue.