rhinorrhea
Meaning of rhinorrhea: The color and thickness of nasal discharge say far less about its cause than most people assume.
Definition of rhinorrhea
Rhinorrhea is the medical term for a runny nose: fluid draining freely from the nostrils because the lining of the nose is producing more mucus than usual, or because the mucus present has become thinner. It is a sign rather than a disease in itself, and it accompanies colds, allergy, cold air, exercise, spicy food and irritant fumes.
What makes the nose run?
The lining of the nose produces mucus constantly to trap dust and to keep inhaled air moist. Two things increase what escapes from the nostrils. Glands in the lining can be told to secrete far more than usual, which is what happens when a virus infects the surface or when an allergen triggers the release of histamine. Blood vessels beneath the lining can also leak watery fluid into the tissue and out through the surface, which is what cold air, exercise and spicy food provoke. The two mechanisms often run together, and both produce the same visible result.
Does the color of the discharge indicate infection?
Not reliably. Discharge turns yellow and then green as white blood cells arrive and break down, releasing a green enzyme they carry. That happens in an ordinary viral cold as readily as in bacterial infection, usually after the first few days, so the change in color tracks the age of the illness rather than the organism causing it. Discharge that stays clear and watery for weeks, with sneezing and itching, points instead toward allergy, and blood testing in that setting may show eosinophilia, a rise in the white cells tied to allergic reactions.
What are the usual causes?
| Cause | Character of the discharge | Other features |
|---|---|---|
| Viral cold, including RSV in infants | Clear at first, thickening later | Sore throat, cough, mild fever |
| Allergy | Clear and watery, persistent | Sneezing, itchy eyes and nose |
| Cold air or exercise | Thin and watery | Stops when the trigger stops |
| Spicy food | Thin and watery | Immediate and short lived |
| Head injury or skull surgery | Clear, one nostril, positional | Salty taste, headache |
The last row is the one that matters most, because clear fluid running from a single nostril after injury to the face or the base of the skull can be cerebrospinal fluid escaping through a tear in the membrane around the brain rather than mucus. Antihistamine tablets such as fexofenadine and steroid nasal sprays act on the allergic mechanism and do nothing for that situation or for a viral cold.
Also known as
Used in a sentence
Rhinorrhea and sneezing began within minutes of exposure to the animal.
Good to know
Yellow or green discharge reflects white cells breaking down within the mucus and appears in ordinary viral colds, so color does not establish a bacterial cause. Clear watery drainage from one nostril after head injury or skull surgery can be cerebrospinal fluid rather than mucus.
Word origin
Where “rhinorrhea” comes from
From the Greek rhis, rhinos, meaning nose, joined to rhoia, a flowing or discharge.