A runny nose, known as rhinorrhea, is the discharge of fluid from the nasal passages. This common symptom can range from a thin, clear fluid to a thicker, opaque substance. It can stem from various factors, from environmental triggers to health conditions.
The Body’s Natural Response
A runny nose often serves as a protective mechanism. When airborne irritants like dust, pollen, or smoke enter the nasal passages, the nose increases mucus production to trap and flush out these foreign particles. This process helps cleanse the airways.
The body also adapts to environmental changes, such as exposure to cold air. In chilly conditions, the nasal lining produces more mucus to warm and humidify the air before it reaches the respiratory system. This protects delicate mucous membranes and lung tissue from the dry, cold environment.
Increased mucus production can also be an early part of the immune system’s response to pathogens. By creating more mucus, the body attempts to trap and expel viruses or bacteria before they establish a full infection. This initial flush helps wash germs from the nose and sinuses.
Beyond physical irritants and infections, emotional responses can trigger a runny nose. When a person cries, tears drain through tear ducts into the nasal cavity. These tears mix with mucus, causing fluid to drip from the nose.
Understanding Nasal Discharge
The appearance of nasal discharge can offer insights into its underlying cause. Clear and watery discharge is commonly associated with allergies or the early stages of a viral infection. It can also be a response to environmental factors.
As a viral infection progresses, nasal mucus may become thicker and change from clear to white or yellow. This shift indicates an increased immune response as the body sends more immune cells to fight the infection. The thickening is due to these immune cells and trapped foreign particles accumulating in the mucus.
Green nasal discharge, often mistakenly seen as a definitive sign of bacterial infection, primarily indicates the presence of myeloperoxidase. This enzyme is released by white blood cells (neutrophils) that fight infection. Its appearance means the immune system is actively engaged in combating a pathogen, often a viral cold in its later stages.
Bloody discharge can result from dry nasal passages, frequent nose blowing, or minor irritation. If the bleeding is heavy, persistent, or occurs without a clear cause, it may warrant further attention.
When to Seek Medical Advice
While many instances of a runny nose resolve on their own, certain signs suggest the need for medical evaluation. Seek advice if a runny nose persists for more than 10 to 14 days, especially if symptoms do not improve or worsen. A prolonged runny nose can indicate an underlying issue beyond a typical cold or allergy.
Medical attention is also advisable if a runny nose is accompanied by severe symptoms. These include a high fever, intense headache, significant facial pain or pressure, shortness of breath, a stiff neck, or changes in vision. These symptoms could point to more serious conditions.
Specific changes in discharge, combined with other concerning symptoms, should prompt a doctor’s visit. For example, green or yellow discharge with worsening symptoms, high fever, or severe sinus pain warrants evaluation. If bloody discharge is heavy, persistent, or occurs after a head injury, it requires immediate medical assessment.
For infants and young children, a healthcare professional should be consulted if a baby’s runny nose is associated with a high fever, difficulty breathing, poor feeding, or unusual lethargy. In babies younger than three months, any fever or signs of illness should be reported to a doctor early.