Learning Center: Nasal Breathing

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anatomy of the nose

Last reviewed: October 4, 2026

Introduction

Trouble breathing through the nose (nasal obstruction) is one of the most common reasons people see an otolaryngologist. It can come from swelling of the nasal lining, which changes from day to day, or from the structure of the nose, which does not. Swelling is caused by allergies, irritants, infections and overuse of decongestant sprays, and it is treated mainly with medication. Structural causes include a deviated septum, enlarged turbinates and a weak or narrow nasal valve, and they are treated with surgery or office procedures when medication is not enough. Many people have more than one cause, so the evaluation looks at all of them.

Symptoms are often measured with the NOSE (Nasal Obstruction Symptom Evaluation) scale, a validated five-question survey scored from 0 to 100 that rates congestion, blockage, trouble breathing through the nose, trouble sleeping and air hunger with exercise [1]. The scale helps track how much a treatment helps.

This page covers the anatomy of the nose, the normal nasal cycle, swelling of the lining, and the three main structural causes of obstruction, with the evidence for each treatment. A numbered reference list is at the end of the page.

Anatomy

Air enters through the nostrils and passes the nasal valve, the narrowest part of the airway, formed by the septum, the side wall of the nose and the front end of the inferior turbinate. Because airflow resistance rises steeply as a passage narrows, small changes here make a large difference in how easily a person breathes.

The septum is the wall of cartilage and bone that divides the nose into left and right sides. On the side walls are three curled shelves of bone covered by thick lining, the inferior, middle and superior turbinates. The turbinates warm, humidify and filter the air, and their lining contains spongy blood vessels that swell and shrink. Behind the nose, the nasal passages open into the nasopharynx and the throat. The sinuses drain into the nose under the middle turbinate (see the sinusitis page).

nasal cycle

The nasal cycle is the unconscious alternating partial congestion and decongestion of the nasal cavities. This results in greater airflow through one nostril with periodic alternation between the nostrils. It is a physiological congestion of the nasal turbinates (curled bony projections within the nasal cavities), due to blood filling up spaces in the tissue on one side while the opposite side’s turbinates relatively free of blood. One side is congested while the other side is decongested for an average of duration of two and a half hours (but the duration varies widely with age, body-posture, and other conditions), and then the sides switch, and the previously decongested side becomes congested. The nasal cycle should not be confused with pathological nasal airway resistance.

In a classic study that measured airflow resistance on each side for about seven hours, 36 of 50 healthy adults (72%) showed at least one full nasal cycle [2]. Most people do not notice it because total airflow through both sides stays about the same. It becomes noticeable when one side is already narrowed, for example by a deviated septum, because the normal swelling of that side then blocks it. Lying on one side also makes the lower side congest. A blockage that alternates from side to side is usually the nasal cycle; a blockage that is always on the same side points toward a structural cause.

inflammation and swelling of the lining

The lining of the nose swells in response to many triggers. Common causes include:

Allergic rhinitis: swelling, sneezing, itching and runny nose triggered by pollens, dust mites, pets or molds. Allergy testing identifies the triggers. Steroid nasal sprays are the most effective single medication for allergic rhinitis and are the only common allergy medication that substantially relieves congestion; antihistamine nasal sprays are also effective, and allergen immunotherapy (allergy shots or tablets) is an option when medications are not enough [3, 4].
Nonallergic rhinitis: similar symptoms triggered by temperature changes, odors, smoke or spicy food, without allergy. Steroid and antihistamine sprays help, and an ipratropium spray helps a runny nose [4].
Rhinitis medicamentosa: rebound congestion from using decongestant sprays such as oxymetazoline for more than a few days. Each dose works for a shorter time, leading to more frequent use. Treatment is stopping the spray, usually with a steroid nasal spray to ease the transition [5]. Decongestant sprays should be limited to a few days at a time [4]. See also its treatment.
Infections and sinus disease: colds, sinus infections and chronic rhinosinusitis, including nasal polyps (see the sinusitis page).
Other causes: pregnancy, hypothyroidism, some blood pressure medications and other drugs, and in children, enlarged adenoids.

Saline rinses (see saline) clear mucus and irritants and are a safe addition to any of these treatments. Steroid sprays work best when used daily and aimed slightly outward, away from the septum, and take several days to reach full effect.

deviated nasal septum

The septum is rarely perfectly straight, and a mild bend usually causes no symptoms. A deviation matters when it narrows one or both sides enough to cause obstruction, especially when it involves the front of the septum near the nasal valve. It can be present from birth or follow an injury. Septal deviation does not respond to medication, although treating swelling of the lining can make it less noticeable.

Septoplasty straightens the septum through the nostrils, without an outside incision, by reshaping or removing the bent cartilage and bone. Two randomized trials have compared septoplasty with medication alone in adults with a deviated septum and nasal obstruction:

In a Dutch trial of 203 adults, septoplasty (with turbinate surgery when needed) led to better health-related quality of life at 12 months than nonsurgical treatment, and the benefit lasted through 24 months [6].
In the British NAIROS trial of 378 adults, sinonasal symptom scores at six months were about half as high after septoplasty as after medical treatment with a steroid spray and saline (a 20-point difference on the 22-item SNOT-22 survey). People with more severe symptoms at the start benefited most [7].

Septoplasty carries small risks, including bleeding, infection, a hole in the septum (perforation) and, rarely, numbness of the front teeth or a change in the shape of the nose; there were more adverse events after surgery than after medication in NAIROS [6, 7]. An American Academy of Otolaryngology–Head and Neck Surgery consensus statement gives guidance on patient selection and counseling for septoplasty with or without turbinate reduction [8]. More information is on the septoplasty page.

enlarged turbinates (turbinate hypertrophy and concha bullosa)

The inferior turbinates can be enlarged permanently, from long-standing allergic or nonallergic rhinitis, or on one side to fill the extra space opposite a deviated septum. A concha bullosa is an air pocket inside the middle turbinate that makes it larger; it is common, usually harmless, and occasionally contributes to obstruction or sinus blockage.

When enlarged turbinates continue to block breathing despite steroid sprays and allergy treatment, they can be reduced. Modern techniques shrink or reposition the turbinate while preserving its lining, using radiofrequency energy, a microdebrider under the lining, or outfracture (moving the turbinate toward the side wall). These are often done together with septoplasty and sometimes in the office. Turbinate reduction is widely performed and generally effective, but high-quality randomized trials are limited, particularly for patients with allergic rhinitis [9]. In the NAIROS septoplasty trial described above, the improvement after surgery did not depend on whether turbinate reduction was added [7].

Removing too much turbinate tissue can lead to empty nose syndrome, an uncommon condition in which the nose feels blocked or the person feels short of breath despite a wide-open airway, often with dryness and crusting. It is difficult to treat, which is why turbinate tissue is preserved [10]. More information is on the turbinate reduction page.

nasal valve(s)

Nasal valve compromise is narrowing or collapse at the nasal valve. It may be static (narrow all the time, from the shape of the nose, a deviated front septum or a prior injury or surgery) or dynamic (the side wall of the nose collapses inward when breathing in, from weak cartilage). A national consensus panel concluded that nasal valve compromise is a distinct condition best diagnosed by history and examination, that CT scans are not useful for diagnosing it, and that steroid sprays do not help it unless rhinitis is also present [11]. A simple test is gently pulling the cheek outward beside the nose (the Cottle maneuver) or supporting the side wall with a small instrument; breathing that improves suggests a valve problem. See nasal valve collapse and nasal airflow.

Treatment options include:

Nasal strips and internal dilators: inexpensive, help many people, especially during sleep or exercise, and also serve as a test of whether opening the valve will help [11].
Surgery: the main treatment. Cartilage grafts (often taken from the septum) strengthen or widen the side wall or the angle between the septum and side wall, usually as part of a functional rhinoplasty [11]. See the rhinoplasty page.
Office procedures: in a sham-controlled randomized trial, temperature-controlled radiofrequency treatment of the valve (VivAer) gave a meaningful improvement in 88% of treated patients compared with 43% after a sham procedure at three months [12], with results maintained at two years [13]. In another sham-controlled trial, an absorbable implant placed to support the side wall (Latera) gave a meaningful improvement in 83% compared with 55% after sham [14]. These procedures are done under local anesthesia and are reasonable for selected patients with milder collapse; the trials were funded by the device makers, and long-term comparisons with surgery are limited.

Summary

Nasal obstruction comes from swelling of the lining, from the structure of the nose, or both; the NOSE scale measures symptoms and response to treatment [1].
The nasal cycle is a normal side-to-side alternation in congestion; blockage that always stays on one side suggests a structural cause [2].
Swelling from allergic and nonallergic rhinitis is treated first with steroid and antihistamine sprays and saline; decongestant sprays should be limited to a few days [3, 4, 5].
For a deviated septum causing obstruction, two randomized trials found septoplasty better than medication alone [6, 7].
Enlarged turbinates can be reduced with techniques that preserve the lining, to avoid empty nose syndrome [9, 10].
Nasal valve compromise is diagnosed by examination and treated with dilators, surgery, or office procedures that outperformed sham in randomized trials [11, 12, 14].

References

Stewart MG, Witsell DL, Smith TL, et al. Development and validation of the Nasal Obstruction Symptom Evaluation (NOSE) scale. Otolaryngol Head Neck Surg. 2004;130(2):157-63. doi:10.1016/j.otohns.2003.09.016 PubMed 14990910
Hasegawa M, Kern EB. Variations in nasal resistance in man: a rhinomanometric study of the nasal cycle in 50 human subjects. Rhinology. 1978;16(1):19-29. PubMed 635366
Seidman MD, Gurgel RK, Lin SY, et al. Clinical practice guideline: Allergic rhinitis. Otolaryngol Head Neck Surg. 2015;152(1 Suppl):S1-43. doi:10.1177/0194599814561600 PubMed 25644617
Dykewicz MS, Wallace DV, Amrol DJ, et al. Rhinitis 2020: A practice parameter update. J Allergy Clin Immunol. 2020;146(4):721-767. doi:10.1016/j.jaci.2020.07.007 PubMed 32707227
Zucker SM, Barton BM, McCoul ED. Management of Rhinitis Medicamentosa: A Systematic Review. Otolaryngol Head Neck Surg. 2019;160(3):429-438. doi:10.1177/0194599818807891 PubMed 30325708
van Egmond MMHT, Rovers MM, Hannink G, et al. Septoplasty with or without concurrent turbinate surgery versus non-surgical management for nasal obstruction in adults with a deviated septum: a pragmatic, randomised controlled trial. Lancet. 2019;394(10195):314-321. doi:10.1016/S0140-6736(19)30354-X PubMed 31227374
Carrie S, Fouweather T, Homer T, et al. Effectiveness of septoplasty compared to medical management in adults with obstruction associated with a deviated nasal septum: the NAIROS RCT. Health Technol Assess. 2024;28(10):1-213. doi:10.3310/MVFR4028 PubMed 38477237
Han JK, Stringer SP, Rosenfeld RM, et al. Clinical Consensus Statement: Septoplasty with or without Inferior Turbinate Reduction. Otolaryngol Head Neck Surg. 2015;153(5):708-20. doi:10.1177/0194599815606435 PubMed 26527752
Jose J, Coatesworth AP. Inferior turbinate surgery for nasal obstruction in allergic rhinitis after failed medical treatment. Cochrane Database Syst Rev. 2010;2010(12):CD005235. doi:10.1002/14651858.CD005235.pub2 PubMed 21154359
Leong SC. The clinical efficacy of surgical interventions for empty nose syndrome: A systematic review. Laryngoscope. 2015;125(7):1557-62. doi:10.1002/lary.25170 PubMed 25647010
Rhee JS, Weaver EM, Park SS, et al. Clinical consensus statement: Diagnosis and management of nasal valve compromise. Otolaryngol Head Neck Surg. 2010;143(1):48-59. doi:10.1016/j.otohns.2010.04.019 PubMed 20620619
Silvers SL, Rosenthal JN, McDuffie CM, et al. Temperature-controlled radiofrequency device treatment of the nasal valve for nasal airway obstruction: A randomized controlled trial. Int Forum Allergy Rhinol. 2021;11(12):1676-1684. doi:10.1002/alr.22861 PubMed 34240571
Silvers SL, McDuffie CM, Yen DM, et al. Two-year outcomes of radiofrequency device treatment of the nasal valve for nasal airway obstruction. Rhinology. 2024;62(3):310-319. doi:10.4193/RhinRhin23.377 PubMed 38217847
Stolovitzky P, Senior B, Ow RA, et al. Assessment of bioabsorbable implant treatment for nasal valve collapse compared to a sham group: a randomized control trial. Int Forum Allergy Rhinol. 2019;9(8):850-856. doi:10.1002/alr.22362 PubMed 31226238

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