In short
- Most people have a septum that's a little off-center, and most of them have no symptoms.
- A severely deviated septum usually makes breathing harder on one side, and the blockage tends to stay put.
- Allergies usually bring itching, sneezing, a runny nose and watery eyes, and often follow seasons or triggers.
- Medicines can ease congestion from either cause, but healthdirect says they won't change the shape of the septum.
- An ENT or other doctor can examine the inside of your nose and check for allergies, polyps and other causes of a persistent blockage.
A deviated septum usually blocks one side of your nose most of the time, and the blockage doesn't change much with the seasons. Allergies tend to come with itching, sneezing, a runny nose and watery eyes, and they flare with pollen, dust or pets. You can have both, and if a blockage is persistent, an ENT doctor can tell you which one you're dealing with.
The good news is that either way, there's a lot you can do to breathe more easily at night. Here's how to read the clues.
What is a deviated septum?
The septum is the thin wall of bone and cartilage that divides the inside of your nose into two sides. healthdirect Australia says a deviated septum means it's crooked, which can make one side narrower than the other. You can be born with it or it can follow an injury to the nose.
It's very common. Cleveland Clinic puts it at about 8 out of 10 people. healthdirect says most people have no symptoms and may not know they have one. A crooked septum only matters when it gets in the way of your breathing.
What are the signs of a deviated septum?
healthdirect says that with a severe deviation, the most common symptom is difficulty breathing through the nose, usually worse on one side. It also lists a blocked nose on one side or switching between nostrils, nosebleeds, frequent sinus infections, headaches or facial pain, and snoring and noisy breathing during sleep. Our guide to deviated septum symptoms covers these in more detail.
Cleveland Clinic suggests a simple check: hold one nostril closed and notice how easily you breathe through the other, then switch. Trouble on one or both sides could point to a deviated septum, but it says the only sure way to know is a diagnosis from a healthcare provider. Our nose test walks you through a similar check.
What are the signs of allergies?
Allergic rhinitis happens when you breathe in something you're allergic to, such as pollen, mold, animal dander or dust. MedlinePlus lists symptoms that come on shortly after contact, including an itchy nose, mouth, eyes or throat, sneezing, a runny nose and watery eyes. Stuffiness, coughing and fatigue can follow later.
Timing is the other clue. When pollen is the trigger, MedlinePlus says the allergy may occur only during certain seasons, and the NHS notes that hay fever can last for weeks or months, unlike a cold. Our guide to hay fever and sleep covers pollen season.
How can you tell them apart?
The easiest way to tell a deviated septum from allergies is to put the clues side by side.
A blockage that stays on the same side, day after day and season after season, points toward something structural like a deviated septum. Cleveland Clinic says that if you consistently have congestion on one side, a structural issue might be responsible.
Itching, sneezing, watery eyes and symptoms that come and go with pollen, pets or dust point toward allergies. MedlinePlus says doctors ask whether symptoms vary by time of day or season and about exposure to pets and other allergens.
A blocked side that switches is often normal. Cleveland Clinic explains that in the nasal cycle, one side of the nose becomes more congested and the other less so every four to six hours. Sleeping on your side can also stuff up the nostril facing the pillow. Read more in the nasal cycle.
How you respond to allergy treatment can be a hint too. healthdirect says medicines can ease symptoms such as a blocked or runny nose, but they won't change the shape of your septum. If allergy treatment clears your nose, allergies were likely a big part of it. If one side stays blocked, ask about the structure.
Can it be something else?
A blocked nose can come from something other than a deviated septum or allergies. When a doctor examines a blocked nose, healthdirect says they also check for allergies, infections, nasal polyps, overuse of nasal sprays and, rarely, a tumor. That's one reason a persistent blockage deserves a proper look rather than a guess.
Can nasal strips help a deviated septum or allergies?
Research: limited (what this means)Nasal strips can make breathing easier with either a deviated septum or allergies. US regulations describe a nasal dilator as intended to provide temporary relief from breathing difficulties caused by structural abnormalities and/or transient nasal congestion. The external version uses a spring material and skin adhesive to gently pull the nostrils open.
A 1998 study in Laryngoscope tested an external nasal dilator in people with congestion from swollen nasal lining, people with a septal deviation in the nasal valve area at the front of the nose, and healthy people. The dilator opened the airway and lowered nasal resistance in all three groups. The effect was largest in the septal deviation group, and the authors called the dilator an effective nonsurgical option for that kind of deviation. People in the congestion group improved on the measurements but didn't clearly feel the difference.
So strips tend to do the most when the narrowing is near the front of the nose. They don't straighten a septum or treat an allergy, but they can make nights more comfortable while you sort out the cause. See do nasal strips help with a deviated septum? and nasal strips for allergies.
If you use mouth tape, save it for nights when you can breathe comfortably through your nose.
Check this first. Skip mouth tape and see a doctor if you snore loudly, wake up gasping, have been told you stop breathing in your sleep, or can't breathe comfortably through your nose. More on safety
When should you see a doctor or ENT?
If your nose is blocked most of the time, see a doctor rather than living with it. Cleveland Clinic suggests talking to a provider if symptoms interfere with your breathing, disrupt your sleep or affect other parts of your life, and to tell your provider about frequent nosebleeds. MedlinePlus advises contacting a provider if allergy symptoms are severe or stop responding to treatment.
An ENT can examine your nose inside and out, and healthdirect says this may include a nasal endoscope, a thin tube with a light and camera. Many deviations never need treatment. If one is causing ongoing problems, Cleveland Clinic says septoplasty is the only way to fix it. healthdirect also lists obstructive sleep apnoea among possible symptoms of a severe deviation, so snoring with gasping or pauses in breathing is a reason to see a doctor promptly; our guide to snoring vs sleep apnea explains why.
Our pick (paid partner)
For easier breathing while you work out the cause, our pick is TitanAir Nasal Strips. This is our recommendation, not the result of testing or ranking products ourselves.
Titan says the strips are drug-free external nasal dilators with flexible spring-loaded bands, placed just above the flare of the nostrils on the soft part of the nose rather than the bony bridge. Titan offers a 30-night guarantee. More is on our nasal breathing topic page.
Read next
- Deviated septum: symptoms, nighttime effects and when to see an ENT
- Why is my nose stuffy at night?
- Hay fever and sleep: 9 tips for pollen season
Common questions
How do I know if I have a deviated septum or allergies?
Look at the pattern. A deviated septum tends to block the same side most of the time, while allergies often come with itching, sneezing and watery eyes and change with seasons or exposure. Only an exam can confirm a deviated septum.
Can you have a deviated septum and allergies at the same time?
Yes, they're separate problems. When doctors examine a nose for a deviated septum, healthdirect says they also check for other causes such as allergies, infections and nasal polyps.
Is it normal for one nostril to be blocked?
Often, yes. Cleveland Clinic says the nasal cycle makes one side more congested and the other less congested every four to six hours. A blockage on one side that never switches is worth getting checked.
Do nasal strips help with a deviated septum?
They can, when the narrowing is near the front of the nose. In a 1998 study, an external nasal dilator opened the nasal airway in all groups, with the biggest effect in people with a deviation in the nasal valve area. A strip doesn't straighten the septum, but it can make breathing through the nose easier at night.
When should I see an ENT about a blocked nose?
If the blockage is persistent, affects your sleep or keeps coming back despite treatment. Cleveland Clinic suggests seeing a provider if symptoms interfere with breathing or disrupt your sleep, and frequent nosebleeds or sinus infections are also reasons to go.
Can a deviated septum be fixed without surgery?
Medicines and nasal strips can ease symptoms, but Cleveland Clinic says the only way to fix a deviated septum is septoplasty. Many people with a deviation never need treatment.
Sources
About this article
- Research
- 8 published sources, listed above.
- Evidence
- Limited. How we rate it
- Last checked
- October 10, 2026
- Funding
- Paid partner of Titan Recovery. Their ads are labeled.
- Found an error?
- Tell us. We log fixes on the corrections page.
* This content is for informational and educational purposes only and is not medical advice. It is not intended to diagnose, treat, cure or prevent any disease or health condition. Talk to a qualified healthcare provider about your health.
