A swollen feeling inside one nostril is usually caused by something harmless, like your body’s natural nasal cycle or mild irritation. But one-sided nasal swelling can also signal infections, structural issues, or (rarely) something that needs prompt medical attention. The cause depends on how long it’s lasted, whether you have other symptoms, and whether it came on suddenly or gradually.
Your Nose Naturally Swells One Side at a Time
Before assuming something is wrong, it helps to know that your body deliberately swells one nostril more than the other throughout the day. This is called the nasal cycle. Blood flow increases to erectile tissue along the septum and the inferior turbinate of one nostril, physically narrowing the airway on that side while the other side opens up. Then the two sides switch.
The average cycle lasts about two hours while you’re awake, though it can range anywhere from 15 minutes to over 10 hours. During sleep, each side stays dominant for longer, averaging around 4.5 hours. Everyone does this, but most people never notice it unless they’re congested or paying close attention. If the swelling you’re feeling alternates sides and doesn’t come with pain, discharge, or visible sores, the nasal cycle is the likeliest explanation.
Nasal Vestibulitis: Infection Near the Opening
If the swelling is near the front of your nostril and it hurts, you may have nasal vestibulitis. This is an infection of the skin and hair follicles just inside the nose, usually caused by Staphylococcus bacteria. It shows up as pimple-like sores inside the nostril, along with pain, redness, and sometimes yellow crusting or scabbing around the septum.
Common triggers include picking your nose, plucking nasal hairs, blowing your nose too hard, nose piercings, or having a persistent runny nose from allergies. It can also develop as a complication of a cold, herpes simplex, or shingles. Most cases respond well to topical antibiotic ointment, but if it spreads or becomes a boil, you’ll need stronger treatment.
A Deviated Septum
The septum is the thin wall between your two nasal passages. In many people, it’s not perfectly centered. When it leans to one side, the passage on that side becomes physically smaller, which can make the inside of that nostril feel swollen or blocked even though the tissue itself isn’t inflamed. A deviated septum can be something you were born with or the result of an injury.
This matters here because a deviated septum also triggers a chain reaction: the turbinate (a shelf-like structure inside your nose) on the opposite, wider side often enlarges to compensate. So you can end up with genuine tissue swelling on one side as an indirect result of a structural problem on the other. If you’ve had one-sided stuffiness for months or years and it doesn’t switch sides, a deviated septum with compensatory turbinate hypertrophy is a common explanation.
Sinus Infection on One Side
A viral cold typically causes congestion on both sides, and most resolve within three to five days. But if swelling, pressure, and thick discharge persist on one side for more than 10 days, or if symptoms improve and then suddenly get worse again (sometimes called “double worsening”), it may have progressed to acute bacterial sinusitis. High fever over 102°F with one-sided purulent discharge and facial pain lasting three to four consecutive days early in the illness is another pattern that points toward a bacterial cause.
Nasal Polyps
Polyps are smooth, grape-like growths that develop from the lining of the nasal passages. They’re painless and semi-translucent, and when they get large enough, they block airflow and make the inside of your nose feel swollen. Most inflammatory polyps show up on both sides. A polyp appearing on only one side is clinically significant because it raises the question of whether it’s truly a polyp or something else. Benign one-sided polyps do exist (a type called an antrochoanal polyp, for example), but a unilateral mass generally warrants evaluation by an ear, nose, and throat specialist to rule out other diagnoses.
Septal Hematoma After an Injury
If you recently took a hit to the nose and now one side feels swollen, painful, and blocked, check for a septal hematoma. This is a collection of blood between the layers of the septum that creates a soft, balloon-like swelling inside the nostril. Left untreated, it can become infected or cut off blood supply to the cartilage, eventually leading to a hole in the septum or a visible collapse of the nose’s outer shape (called saddle nose deformity). A septal hematoma needs to be drained promptly. Any nasal injury followed by congestion and pain should be evaluated quickly.
Red Flags Worth Knowing
The vast majority of one-sided nasal swelling is benign. But certain symptoms in combination deserve attention, because nasal and sinus tumors, while uncommon, almost always present on one side. Benign conditions like general rhinosinusitis don’t usually behave that way.
Symptoms that warrant evaluation by an ENT specialist include:
- Persistent one-sided blockage that doesn’t respond to decongestants or allergy treatment
- Bloody discharge from one nostril only
- Facial numbness, particularly of the cheek
- Loose teeth or dentures that suddenly don’t fit, caused by swelling in the upper jaw area
- Facial pain on one side that doesn’t resolve
- Visual changes, including double vision or a bulging eye
None of these symptoms automatically means cancer. Many have straightforward explanations. But unilateral nasal blockage with any of these additional features will typically prompt an ENT doctor to perform an endoscopic exam and, if they find a mass, a biopsy to determine what it is.
What Doctors Look For
If you go in for evaluation, expect a head and neck exam with close attention to any visible swelling, both inside and outside the nose. For suspected infections, the clinical exam and your symptom timeline are usually enough to guide treatment. For anything that looks like a mass or polyp, most ENT specialists use fiberoptic sinus endoscopy, a thin flexible camera threaded into the nose, to get a clear view. Imaging like a CT scan is reserved for cases where complications are suspected or surgery is being considered. MRI comes into play only when there’s concern about a fungal infection or tumor.