Reflex runny nose

How it works

Exercise, cold air, and hot or spicy food can all make the nose pour out a thin, watery fluid¹²³. It happens in people with and without allergies³⁴.

Cold air has the clearest evidence. In a trial, 14 ski patrollers used an atropine nasal spray. Atropine blocks acetylcholine, the nerve signal that tells the nose glands to make fluid². The drip improved in 92% of them, and a dummy spray changed nothing³. So a nerve signal drives the fluid. It may not be the only cause. In lab tests, a cold-air runny nose also shows a release of chemical signals like that of an allergy test⁷.

Spicy food works through a reflex too. The drip starts within a few minutes of eating, usually without itching or sneezing². The leading idea is that the food excites the trigeminal nerve, which senses pain and heat in the mouth. It then signals the nose glands. Atropine sprays help here too².

Exercise adds a paradox: it opens the nose. In one study, cycling lowered the resistance to airflow through the nose in all 6 people tested⁶. Yet in many people it still runs⁴. A 2024 review calls exercise-induced rhinitis poorly understood. It says the cause is broadly believed to be an imbalance in the automatic nervous system¹.

How common it is

In a 2006 survey of 164 adults who exercise, 61% reported more nose symptoms with indoor exercise and 56% with outdoor exercise. A runny nose was the most common symptom⁴. In the cold, 96% of 90 patients at a ski resort clinic reported some runny nose³. At a dermatology clinic, 69% of 571 people named a food that made their nose run, most often hot chili peppers⁵. None of these groups was random, so the true rate for everyone is not known³⁴⁵.

Is it a problem?

Usually not. It is a normal reflex, not an infection. In the food survey, 46% of people with it were never bothered by it⁵.

Mention it to a doctor if a thin, clear drip comes from one side only and keeps coming. At one specialist nose clinic, 30% of 146 patients with a one-sided clear drip had a leak of the fluid around the brain. These were patients sent to a specialist, so the figure does not apply to everyone⁸. After a head injury, clear fluid from the nose needs emergency help⁹.

History and culture

In 1991, a doctor described skier’s nose as common but not yet covered in the medical literature³. In 2019, the cyclist Chris Froome lost control of his bike at 37 mph (about 60 km/h) while wiping his nose. He was admitted to intensive care¹.