① Allergic rhinitis is one of the most common causes.
Pollen, house dust, and other allergens can cause swelling of the nasal mucous membrane, leading to nasal congestion.
[Main symptoms]
• Nasal congestion • Sneezing • Clear nasal discharge • Itchy eyes

② Sinusitis (chronic rhinosinusitis)
Inflammation of the sinuses can occur after a cold, etc.
It can cause nasal congestion.
[Main symptoms]
Symptoms include: nasal congestion, yellow nasal discharge, postnasal drip, cough, and pain in the cheeks or forehead. If left untreated, these symptoms may persist for a long time.

③ Deviated nasal septum: This is a condition in which the wall separating the left and right sides of the nose (nasal septum) is bent.
[Main symptoms]
Symptoms include: • Congestion on one side of the nose • Chronic nasal congestion • Snoring • Mouth breathing Depending on the severity, surgical treatment may be considered.

④ Nasal polyps
This is a benign swelling that forms inside the nose.
[Main symptoms]
Symptoms may include: nasal congestion, difficulty smelling, postnasal drip, and mouth breathing. These symptoms may be associated with chronic sinusitis.

⑤ Vasomotor rhinitis Even if allergy tests show no abnormalities,
Nasal symptoms can occur due to temperature changes, fatigue, stress, etc.

⑥ Common cold (acute rhinitis)
It's usually just a temporary nasal congestion that improves within a few days to a week.

⑦ Eosinophilic sinusitis is often accompanied by nasal polyps.
This is a disease characterized by a loss of smell and persistent severe nasal congestion.
Treatment or surgery may be necessary.