Blocked Nose: Why It Happens and How to Fix It

Close-up of a person with a blocked nose, holding a tissue

A blocked nose happens when inflamed sinuses trap mucus, blocking airflow. This swelling is usually triggered by infections, allergies, or irritants.

How It Works

Your nose filters, warms, and moistens air using tiny hairs and mucus. When irritated, blood vessels in your nasal passages swell, narrowing them. Mucus thickens, clogging your nose further.

Main Causes

The most common causes fall into four categories:

Infections: Viral (colds, flu) or bacterial (sinusitis) infections trigger inflammation.
Allergies: Pollen, dust, or pet dander prompt histamine release, causing swelling.
Irritants: Smoke, dry air, or chemical fumes dry out nasal passages, leading to congestion.
Structural Issues: A deviated septum or polyps physically block airflow.

When to Worry

Most cases resolve in a week. See a doctor if:

Congestion lasts over 10 days.
You have a high fever or green/yellow mucus for more than 3 days.
You experience severe facial pain or headaches.

These may indicate sinusitis or other conditions needing treatment.

Common Misconceptions

Many assume a blocked nose is always due to a cold. However, allergies account for about 20% of cases, while structural issues cause chronic congestion in others.

Worked Example

During allergy season, Sarah's nose swells after exposure to pollen. Her immune system releases histamines, inflaming nasal passages. She takes an antihistamine, which blocks histamine receptors, reducing swelling and clearing her nose within hours.

Firsthand Experience

Last winter, I woke up with a blocked nose and tight chest. After ruling out allergies, I realized it was a cold. Steam inhalation and saline sprays helped clear my sinuses within a few days.