A runny nose is characterized by excess production of mucus in the nasal tissues. It is often a bothersome symptom generally caused by allergies or common cold. It might also be triggered by certain factors such as cold weather, tears or eating spicy foods. In some cases, though, it might be an indication of a serious condition such as leakage of brain fluid or cerebrospinal fluid drip.
What are the infectious causes of runny nose?
A runny nose might be triggered by anything that aggravates the nasal tissues. This is frequently triggered by an upper respiratory infection such as common cold or even a sinus infection in some cases.
If linked to an upper respiratory infection, the discharge is due to inflamed nasal tissues by common cold. The sinus infections due to bacteria, virus or mold causes similar symptoms but might be accompanied by facial pain and headache.
Irritants or allergens
An allergy is another usual cause of runny nose. If associated to an allergen, the symptoms of itchiness and sneezing are often present. Allergies trigger the release of histamine which is the chemical responsible for the allergy symptoms.
Vasomotor rhinitis causes overlapping signs with allergies but not an allergic response. Exposure to irritants such as perfume, smoke or even spicy foods increases the production of mucus which leads to a runny nose.
Cold air and crying
A runny nose is triggered by environmental triggers. Inhaling cold air via the nostrils causes the liquid from the air to vaporize and cold air increases the mucus production to moisturize the nasal passages. Both can trigger a watery nose in some individuals.
Crying can also lead to a runny nose once the tear ducts overflow and excess tears drain down the nasal passage.
What are the serious causes?
Watery drainage from one of the nostril might indicate a cerebrospinal fluid (CSF) leak especially if it starts after a head injury.
This occurs if there is a small-sized tear or hole in the membrane surrounding the brain. If not promptly treated, this can progress to a severe infection or other complications.