Loss of Smell: Sinusitis, Nasal Polyps, Allergy or Something Else?

Loss of smell can have a major effect on quality of life. It can reduce enjoyment of food, affect safety, change appetite and make patients feel disconnected from their surroundings. Some people also notice altered taste, although much of flavour depends on smell.

There are many causes of smell loss. Some are temporary after a cold or viral infection. Others are related to chronic nasal inflammation, nasal polyps, allergy or sinus disease. A specialist ENT assessment can help identify whether the smell loss is conductive, inflammatory, post-viral or due to another cause.

At Hampshire ENT Clinics, Mr Tim Biggs and Mr Steve Hayes assess patients with loss of smell as part of their rhinology practice, particularly where symptoms are associated with nasal blockage, chronic sinusitis or nasal polyps.

Quick answer: what causes loss of smell?

Common causes include viral infections, chronic rhinosinusitis, nasal polyps, allergic rhinitis, non-allergic rhinitis, head injury, medication effects and age-related change. If smell loss is persistent, one-sided, associated with bleeding, severe blockage or neurological symptoms, ENT assessment is recommended.

How smell works

Smell depends on odour molecules reaching the smell receptors high in the nose. The signal then travels through the olfactory nerves to the brain. Problems can occur if airflow cannot reach the smell area, if the lining is inflamed, or if the nerve pathway has been affected.

In sinus and nasal disease, smell loss is often caused by inflammation and blockage around the upper nasal cavity, particularly in patients with nasal polyps.

Smell loss after a virus

Viral infections are a common cause of sudden smell loss. Some patients recover quickly, while others have persistent reduced smell or distorted smell. Smell training may be recommended in post-viral smell loss and can also be useful alongside treatment for inflammatory nasal disease.

If smell loss is prolonged or the diagnosis is unclear, ENT assessment can help exclude treatable nasal causes.

Chronic sinusitis and nasal polyps

Chronic rhinosinusitis with nasal polyps is one of the most important treatable causes of smell loss. Patients often have nasal blockage, congestion, post-nasal drip, reduced smell and sometimes asthma or sensitivity to aspirin/NSAIDs.

Treatment may include saline rinses, intranasal steroid sprays or drops, short courses of oral steroid in selected cases, surgery, and in severe recurrent disease, biologic treatments where criteria are met.

Allergy and smell loss

Allergic rhinitis can cause congestion, sneezing, itching and watery discharge. When the nose is very inflamed or blocked, smell can be reduced. Treatment usually starts with allergen avoidance where possible, intranasal steroid sprays, antihistamines and saline irrigation.

If symptoms are persistent despite good treatment, ENT review can check for nasal polyps, septal deviation, turbinate enlargement or chronic sinusitis.

When smell loss should be assessed urgently

Most smell loss is not dangerous, but certain symptoms need prompt assessment. These include one-sided blockage, bleeding, crusting, facial swelling, eye symptoms, severe headache, neurological symptoms, or a progressive one-sided loss of smell.

A careful nasal examination and nasendoscopy can identify whether there is a visible cause within the nose.

What happens at an ENT assessment?

The consultation explores timing, severity, triggers, nasal blockage, sinus symptoms, allergy, viral illness, head injury, medication history and safety issues. Nasendoscopy may be performed to inspect the nasal cavity, smell cleft region and sinus drainage areas.

A CT scan may be arranged if chronic sinusitis, nasal polyps or structural obstruction is suspected.

Treatment options

Treatment depends on the cause. Inflammatory disease may improve with steroid nasal treatments and saline rinses. Nasal polyps or chronic sinusitis may need more intensive medical therapy or endoscopic sinus surgery. Post-viral smell loss may be supported with smell training.

The key is matching treatment to the cause rather than using repeated antibiotics or sprays without a clear diagnosis.

Why see a rhinology specialist?

Smell loss is complex and often frustrating. A rhinology specialist can assess the nose and sinuses in detail, decide whether imaging is needed, identify treatable inflammation or obstruction, and advise on realistic expectations.

Hampshire ENT Clinics provides consultant-led assessment for smell loss, nasal polyps, chronic sinusitis and nasal blockage across Hampshire and the South Coast.

Frequently asked questions

Is loss of smell always caused by COVID or a virus?

No. Viral infections are common causes, but chronic sinusitis, nasal polyps, allergy and structural nasal problems can also reduce smell.

Can nasal polyps cause loss of smell?

Yes. Nasal polyps are a common treatable cause of reduced or absent smell.

Can sinus surgery improve smell?

It can improve smell in some patients with chronic sinusitis or nasal polyps, especially when smell loss is due to inflammatory blockage. Results vary.

What is smell training?

Smell training involves regularly smelling a set of familiar odours to stimulate olfactory recovery. It is often used for post-viral smell loss.

Do steroid nasal sprays help smell loss?

They may help if inflammation, allergy or polyps are contributing. Correct technique and consistent use are important.

Should I have a CT scan for smell loss?

CT may be useful if chronic sinusitis, nasal polyps or structural disease is suspected. It is not needed for every case.

Is one-sided smell loss concerning?

Persistent one-sided symptoms should be assessed, especially if associated with blockage, bleeding or discharge.

Can allergies affect taste?

Yes. Many patients describe loss of taste when the main problem is actually reduced smell from nasal inflammation.

Can smell loss be permanent?

Sometimes, depending on the cause. Treatable nasal inflammation should be assessed because early targeted management may help.

Who treats smell loss at Hampshire ENT Clinics?

Mr Tim Biggs and Mr Steve Hayes assess smell loss related to nasal and sinus disease.