It's often seen as nothing more than whinging about a cold, but 'man flu' really does exist, according to research.
Men suffer more with coughs and colds because they have extra temperature receptors in the brain and so experience worse symptoms.
Children deal with colds the same way because the relevant area of the brain is the same size in boys and girls, said Durham University neuroscientist Dr Amanda Ellison.
But when boys hit puberty testosterone starts to act on the area, called the preoptic nucleus, making it larger.
"When you have a cold one of the things that happens is you get an increase in temperature to fight off the bugs," Dr Ellison said.