Why does nasal mucus (booger) form inside the nose?

Nasal mucus or crusts in the nose may be a normal physiological phenomenon, or they could result from pathological factors such as nasal diseases, upper respiratory tract infections, Sjögren's syndrome, etc.

I. Physiological Phenomenon

The nasal cavity normally contains abundant nasal hairs that filter and remove dust, impurities, and airborne particles inhaled into the nose, preventing them from entering the respiratory system. These impurities mix with nasal secretions and adhere to the nasal mucosa. As moisture evaporates during breathing, they dry out and form nasal crusts (commonly known as "boogers").

II. Pathological Factors

1. Nasal Diseases

Conditions such as chronic rhinitis, deviated nasal septum, and sinusitis can cause structural changes in the nasal mucosa. Patients often experience symptoms like runny nose, nasal congestion, and sneezing. Excessive nasal discharge, when exposed to airflow, loses moisture and dries into crusts that remain in the nasal cavity.

2. Upper Respiratory Tract Infection

The most common example is the common cold, often associated with exposure to cold or pathogen infection. Patients typically develop nasal symptoms accompanied by increased nasal secretions. As these secretions dry due to evaporation, they form significant amounts of nasal crusts.

3. Sjögren's Syndrome

Patients with this condition experience dryness in various body tissues, including the skin and lips. The nasal passages are also prone to dryness, which reduces the secretory function of the nasal mucosa. Secretions decrease in volume, become thicker, and are less likely to drain properly. They then dry within the nasal cavity and form crusts.

If nasal crusts are large enough to cause nasal obstruction, it is advisable to seek medical evaluation at a hospital to determine the underlying cause and receive appropriate treatment.