Why do we get a runny nose when it’s cold?

When temperatures drop, our noses start to to flow sometimes abundantly. This phenomenon, called rhinorrhea by doctors, affects most of us and is due to a purely physiological reaction. Normally, the nose constantly makes a thick, sticky fluid, the mucus, responsible for filtering and humidifying theair outside. In winter, the air becoming dry is cold, immune system cells called mast cells will send a message to the brain to tell it to make more mucus, in order to protect the mucous nasal passage from drying out and to prevent dry air from irritating the lungs.

Water vapor + excess mucus = runny nose

Second mechanism: the brain triggers heating of the nose by increasing blood flow. The condensation exhaled water vapor will then form a ” drop at nose “. A vicious circle sets in: the more the water evaporates, the more it “takes” heat to cold nose, which will manufacture even more liquid. ” We can thus lose 300 to 400 ml of water per day », warns David King, physician at the University of Queensland in Australia. This is why it is necessary to remember to stay hydrated in winter… and to carry plenty of packages tissues before going outside.

Note that some people with favorable ground for rhinitis (asthma or allergy) will tend to have more severe rhinorrhea.