Sinusitis occurs when the normal drainage of mucus from the sinuses is obstructed, leading to inflammation and infection. This blockage creates a moist environment where bacteria, viruses, or fungi can grow. Multiple factors—ranging from infections to structural issues—can contribute to the development of sinusitis.

1. Infections

• Viral infections: The most common cause, especially following the common cold
• Bacterial infections: Develop when mucus remains trapped, allowing bacteria to multiply
• Fungal infections: Less common, but more likely in individuals with weakened immunity

2. Allergies (Allergic Rhinitis)

Allergic reactions to dust, pollen, mold, or pet dander can inflame the nasal lining. This swelling blocks sinus openings and disrupts normal mucus drainage, increasing the risk of sinus infection.

3. Excess Mucus Production

Conditions like colds or chronic allergies can lead to excessive mucus formation. Thick mucus can clog the sinus passages, creating a breeding ground for microbes.

4. Structural Abnormalities

• Deviated nasal septum: A shift in the nasal wall that restricts airflow
• Narrow sinus openings: Naturally small drainage pathways
• Nasal polyps: Soft, non-cancerous growths that block nasal passages

5. Environmental Irritants

Exposure to pollutants such as smoke, dust, chemical fumes, or strong odors can irritate the nasal lining and trigger inflammation, leading to sinus blockage.

6. Weak Immune System

Individuals with low immunity are more susceptible to infections, making it harder for the body to fight off pathogens in the sinuses.

7. Dental Infections

Infections in the upper teeth can spread to the maxillary sinuses due to their close proximity, leading to sinusitis.

8. Frequent Upper Respiratory Infections

Repeated colds or throat infections can cause persistent inflammation of the nasal passages, increasing the likelihood of chronic sinusitis.

9. Lifestyle Factors

• Smoking or exposure to secondhand smoke
• Poor hydration (leading to thick mucus)
• Sudden weather changes
• Poor air quality

Sinusitis typically develops following a common cold or during episodes of untreated or persistent allergic rhinitis. When the sinus passages become blocked and inflamed, pressure builds up within the cavities, leading to a range of uncomfortable symptoms. These may vary depending on whether the condition is acute or chronic, but often affect daily comfort and breathing.

The most noticeable symptom is a feeling of heaviness or pressure in the face—especially around the cheeks, forehead, eyes, or nose—which may worsen on bending forward or lying down.

Common Signs and Symptoms

• Persistent nasal congestion or blocked nose
• Thick nasal discharge, often yellow or green in color
• Postnasal drip with an unpleasant taste in the throat
• Facial pain, tenderness, or pressure
• Headache or a dull, constant heaviness in the head
• Reduced or complete loss of smell and taste
• Cough, which may worsen at night
• Toothache, particularly in the upper jaw
• Swelling around the eyes, cheeks, or face
• General fatigue, weakness, and a feeling of being unwell

Symptoms Based on Severity

• Acute Sinusitis: Symptoms are more intense and short-lived, often accompanied by fever, severe facial pain, and thick nasal discharge
• Chronic Sinusitis: Symptoms persist for several weeks or longer and may be milder but recurrent, commonly including long-term nasal blockage, reduced smell, and ongoing facial discomfort

When to Seek Medical Attention

You should consult a doctor if:

• Symptoms last more than 10 days without improvement
• There is high fever or severe headache
• Swelling around the eyes or vision disturbances occur
• Symptoms keep recurring frequently

An X-ray of the paranasal sinuses is often used as an initial screening tool. It may show haziness or opacities in the affected sinus, suggesting inflammation or fluid accumulation.

However, for a more accurate evaluation—especially in recurrent or chronic cases—additional diagnostic tests may be required to identify the underlying cause and severity of the condition.

Common Diagnostic Tests Include:

• Nasal Endoscopy: A thin, flexible scope is used to directly visualize the nasal passages and sinus openings
• CT Scan of the Sinuses: Provides detailed imaging to assess blockage, structural abnormalities, and extent of infection
• Mucus Culture: Helps identify the specific bacteria or pathogens responsible for infection
• Allergy Testing: Detects allergic triggers that may be contributing to recurrent sinusitis
• Blood Tests: May be used to evaluate infection or underlying immune conditions

Fungal Evaluation

If a fungal cause is suspected, samples of nasal discharge may be collected for microscopic examination (scrapings and smears) and fungal cultures to confirm the diagnosis.