Nasal polyps typically occur in both nostrils. Because they are the result of systemic inflammation affecting the entire nasal and sinus lining, the immune response usually triggers growth on both the left and right sides simultaneously. In the UK, bilateral polyps are frequently seen in patients with underlying conditions such as asthma, aspirin sensitivity, or chronic allergies. These polyps are benign and tend to grow in clusters throughout the sinus cavities.
While bilateral polyps are the norm, it is possible for a growth to occur in only one nostril. This is referred to as a unilateral polyp. When a patient presents with symptoms on just one side, UK medical guidelines require a more cautious approach. A single growth may still be a common polyp, but it can also represent a different type of nasal mass that requires specialised investigation.
What we will discuss in this article
- Why inflammatory nasal polyps usually affect both nostrils
- The clinical significance of a unilateral or single sided nasal growth
- Common symptoms that differ between bilateral and unilateral polyps
- The role of the Antro choanal polyp in one sided nasal blockage
- Why UK doctors prioritise investigations for single sided symptoms
- Diagnostic steps for identifying the nature of a unilateral mass
- When to seek an urgent ENT referral for one sided nasal issues
Why inflammatory polyps are usually bilateral
Most nasal polyps are driven by a type of inflammation that involves the entire respiratory tract. When the immune system is overactive, it does not discriminate between the left and right nasal passages. The triggers that cause the mucous membrane to swell and form polyps, such as airborne allergens or fungal spores, are inhaled into both nostrils.
The significance of unilateral nasal growths
If you have a growth or a complete blockage in only one nostril, it is considered an atypical presentation. While it could simply be a standard inflammatory polyp that has grown much faster on one side, UK specialists must rule out other possibilities.
One specific type of single sided growth is the Antro choanal polyp. These polyps originate in the maxillary sinus and grow through the sinus opening into the back of the nasal cavity. They are almost always unilateral and are more common in children and young adults than the typical inflammatory polyps. Other one sided masses can include inverted papilloma’s, which are benign but locally aggressive, or more rarely, nasal tumours.
Red flags for single sided symptoms
Because of the potential for more serious conditions, any one sided nasal symptom is treated with extra attention in UK ENT clinics. A specialist will look for specific red flags that suggest the growth is not a standard inflammatory polyp.
Key symptoms that require a professional review include:
- Complete blockage on one side: Especially if it does not respond to steroid sprays.
- Persistent nosebleeds: Occurring from the same nostril regularly.
- Visible change in the nose shape: External swelling or deviation on one side.
- Pain or numbness: In the cheek, teeth, or around the eye on the affected side.
- Blood stained discharge: Specifically coming from only one nostril.
Comparison: Bilateral vs Unilateral Nasal Polyps
| Feature | Bilateral Polyps | Unilateral Polyp |
| Common Cause | Asthma or chronic allergies | Antro choanal polyp or structural issue |
| Symmetry | Both nostrils affected | Only one side affected |
| UK Medical View | Suggests chronic inflammation | Requires investigation to rule out tumours |
| Sense of Smell | Often totally lost | May be partially preserved |
| Nosebleeds | Rare | More common |
| Initial Treatment | Steroid sprays and drops | Specialist referral and imaging |
To Summarise
Nasal polyps usually occur in both nostrils because they are driven by widespread inflammation of the respiratory lining. This symmetrical pattern is common in UK patients with asthma and long term allergies. However, a growth appearing in only one nostril is an atypical finding that requires a thorough medical investigation. While it may be a simple Antro choanal polyp, specialists must rule out other types of masses. If you experience a persistent blockage, pain, or bleeding on only one side of your nose, it is essential to move beyond home care and seek a professional diagnosis.
If you have a nasal blockage or a visible growth that affects only one nostril, book an appointment with your GP as soon as possible for a physical examination.
Is it common for polyps to be much larger on one side?
Yes. Even with bilateral polyps, one side may feel more blocked than the other if the polyps in that nostril have grown larger. However, a specialist will still check both sides to confirm the presence of inflammatory tissue.
What is an inverted papilloma?
This is a benign growth that usually occurs on one side of the nose. Unlike a soft polyp, it is often firmer and has a higher risk of turning into something more serious if not removed, which is why UK doctors investigate unilateral growths carefully.
Can a deviated septum look like a one sided polyp?
Yes. A deviated septum occurs when the wall between the nostrils is crooked, making one side feel very blocked. To an untrained eye, the bent cartilage or the swollen tissue next to it can be mistaken for a polyp.
Why is my smell okay if I have a polyp in one nostril?
Because the other nostril is clear, scent molecules can still reach the olfactory nerves on that side. This is another reason why unilateral growths are often diagnosed later than bilateral ones.
Will a GP refer me to an ENT for a one sided blockage?
In the UK, a persistent one sided nasal blockage is usually a reason for a specialist referral. This is to ensure a nasal endoscopy can be performed to see the exact nature of the growth.
Can a one sided polyp be treated with sprays?
If the growth is a standard inflammatory polyp that happens to be on one side, steroids may help. However, for many other unilateral masses, surgery is the primary recommendation to ensure a full diagnosis.
Authority Snapshot
This article was reviewed by Dr. Stefan Petrov, a UK trained physician with an MBBS and postgraduate certifications including Basic Life Support (BLS), Advanced Cardiac Life Support (ACLS), and the UK Medical Licensing Assessment (PLAB 1 and 2). Dr. Petrov has extensive clinical experience in general medicine, surgery, and emergency care. He has worked in both hospital wards and intensive care units, performing diagnostic procedures and contributing to patient focused medical education. This guide follows the standard UK clinical pathways for investigating unilateral nasal symptoms and inflammatory airway disease.
