Nasal breathing

Blocked Nose on One Side

Septum, turbinates, allergy or nasal valve?

Why one nostril may feel blocked, including septal deviation, turbinate swelling, allergy, nasal valve issues and when to arrange ENT assessment.

Nasal breathing6 min readGeneral informationUpdated May 2026

A one-sided blocked nose can come from structure, swelling or a combination of both.

Pattern matters

A nose that is always worse on the same side suggests a different problem from congestion that changes side during the day.

More than one cause is common

Septal deviation, turbinate swelling, allergy, polyps and nasal valve narrowing can overlap.

Treatment depends on the cause

The useful first question is not “Do I need surgery?” but “What is narrowing the airway?”

First, is it always the same side?

Many people notice that one nostril feels more open than the other. That can be normal. The lining of the nose naturally swells and decongests in a rhythm called the nasal cycle, so airflow may feel uneven even when nothing serious is happening.

The pattern becomes more important when the blockage is persistent. A nose that is nearly always worse on the same side may point towards a structural narrowing, such as a deviated septum, a narrow nasal valve, scarring or a local obstruction. Blockage that clearly swaps from side to side is often more suggestive of swelling of the nasal lining or turbinates, especially if it changes with allergy, colds, alcohol, lying down, temperature change or irritants.

A helpful starting pointKeep a simple note for one or two weeks: which side is blocked, whether it changes, what makes it worse, whether smell is affected and whether there is mucus, bleeding, facial pressure or snoring.

Common causes of one-sided or uneven nasal blockage

The nose is not a straight pipe. Airflow depends on the septum, turbinates, nasal lining, nasal valve, sinuses and the shape of the outside of the nose. A small change in more than one area can make breathing feel much worse than any single finding might suggest.

Septal deviationThe septum is the wall between the nostrils. If it is bent enough, one side may feel persistently narrow. Some bends are related to growth; others follow injury.

Turbinate swellingTurbinates are normal structures that warm and humidify air. Allergy, infection, irritants and chronic rhinitis can make them swell.

Allergy or rhinitisSneezing, itching, watery eyes, clear mucus and predictable triggers can point towards allergic rhinitis. Non-allergic rhinitis can be triggered by temperature, perfume, smoke, alcohol or spicy foods.

Nasal valve narrowingThe nasal valve is the narrow front part of the airway. It may feel tight at the front of the nose or collapse during stronger breathing, exercise or sleep.

Nasal polyps or sinus inflammationPolyps and chronic inflammation can cause blockage, post-nasal drip, reduced smell, facial pressure and snoring. They often affect both sides but can still feel uneven.

A combined pictureA mild septal bend may not matter until allergy, a cold or turbinate swelling narrows the remaining airway.

Watercolour panels showing different causes of nasal blockage including allergy, swelling, polyps and narrow nasal airflow — The pattern of blockage matters: always the same side, changing sides, seasonal, post-cold, exercise-related or sleep-related.

What an ENT assessment tries to clarify

Assessment usually starts with the story: duration, side, triggers, smell, discharge, bleeding, previous injury, previous nasal surgery, allergy symptoms, sinus symptoms and sleep quality. The outside of the nose may be examined as well as the inside, because a person can have both septal narrowing and nasal valve collapse.

Depending on the symptoms, the nose may be inspected with a light or with a small flexible camera. The aim is to separate inflammatory causes from structural causes. Inflammatory problems may respond to measures such as allergen control, saline irrigation or anti-inflammatory nasal sprays when appropriate. Structural problems such as significant septal deviation, turbinate enlargement or nasal valve narrowing may need a different discussion.

Surgery is not the starting assumption. It is one possible option after the pattern is understood, after medical treatment has been considered, and after the likely benefits and limitations have been discussed.

When to seek medical advice

Arrange a medical review if nasal blockage is persistent, unexplained, always on one side, affecting sleep or exercise, associated with reduced smell, or not settling after a reasonable period. Children with one-sided blockage and unpleasant discharge should be checked because a small object in the nose is one possible cause.

Use urgent care for red flagsSeek urgent advice for severe headache, swelling around the eye, visual symptoms, facial swelling, significant bleeding, high fever, confusion, neck stiffness, or if breathing feels unsafe.

Sources and further reading

This article is general public information and was written using UK, European and well-regarded US sources. It should not replace personal medical advice.

Septal deviation and unilateral nasal obstructionRight Decisions / NHS Scotland
Septal surgeryENT UK
Allergic rhinitisNHS
Nasal polypsNHS
Position statement: nasal valve repairAmerican Academy of Otolaryngology–Head and Neck Surgery