Loss of smell (anosmia) — causes and treatment
Loss of smell dramatically affects quality of life — inability to smell food, the danger of unnoticed smoke or gas, and the loss of emotional connection with scents. After the COVID-19 pandemic, anosmia has become a much more common ENT symptom. The good news is that in many cases it is treatable.
What is loss of smell
We distinguish:
- Anosmia — complete loss of smell
- Hyposmia — reduced sense of smell
- Parosmia — smells perceived differently than they should be (often unpleasant)
- Phantosmia — the patient perceives a smell that isn’t there
There are two basic mechanisms: conductive (air doesn’t reach the receptors — obstruction) and sensorineural (damage to the nerve cells or pathways themselves).
Most common causes
Post-viral anosmia (including COVID-19)
Viruses can damage the olfactory neurons in the nasal mucosa. After COVID-19, millions of people worldwide have lost their sense of smell. Most recover spontaneously within 3–6 months, but there is a significant portion (10–20%) with prolonged or partial recovery.
Chronic rhinosinusitis with polyposis
Polyps and chronic mucosal inflammation mechanically block the airflow to the olfactory receptors. The most common treatable cause — smell often returns within weeks after FESS surgery or conservative therapy.
Deviated nasal septum
A significant deviation can close off one nasal cavity and limit access of odors to the receptor area. Correction with septoplasty often restores the sense of smell.
Allergic rhinitis
Chronic mucosal inflammation reduces the ability to detect smells. Often reversible with adequate therapy.
Traumatic anosmia
A head impact can shear the olfactory neurons where they pass through the cribriform plate. Recovery is limited.
Neurological causes
Anosmia can be an early sign of Parkinson’s disease, Alzheimer’s, or multiple sclerosis. With loss of smell and no obvious ENT cause, a neurological evaluation is warranted.
Medications and toxins
Certain medications (e.g., ACE inhibitors, antibiotics, neuroleptics), exposure to heavy metals, chronic occupational corrosion.
⚠️ When to definitely see a doctor
- Sudden complete loss of smell without infection
- Loss of smell accompanied by headache, vertigo, or vision problems
- Anosmia lasting more than 4 weeks after a cold or COVID
- Parosmia or phantosmia (smells distorted or imaginary)
- Accompanied by nosebleeds or unilateral discharge
Diagnostics
- Detailed history — when it started, whether it was sudden, whether there was a viral infection
- Endoscopic nasal exam — directly shows whether there are polyps, inflammation, deviation, or a mechanical obstruction
- Olfactometry — testing the ability to detect and identify smells
- CT of the paranasal sinuses (as needed) — complete anatomic map
- MRI (as needed) — when a neurological cause is suspected
Treatment
Olfactory training (smell training)
Particularly effective after post-viral anosmia. The patient sniffs 4 different odors (rose, eucalyptus, lemon, clove) for 20 seconds each, twice a day, for 3–6 months. Studies show a significant recovery rate.
Corticosteroids
Topical (nasal spray) or short-term systemic course for polyposis or pronounced inflammation.
Surgical treatment
FESS sinus surgery for polyposis, septoplasty for a significant deviation — often leading to dramatic improvement in the sense of smell.
Allergy / immunotherapy
For allergic rhinitis with anosmia.
💡 Smell training — do it at home
- Prepare 4 scents: rose, lemon, clove, eucalyptus (essential oils)
- Twice a day (morning/evening), 20 seconds per scent
- Try to recall the “true” smell while inhaling
- Patience — it may take 3–6 months for improvement
- Keep a progress diary
Related topics
👃 Nose & sinuses (hub)
🔍 All symptoms
Lost your sense of smell?
A thorough ENT workup identifies the cause and provides a recovery plan. The earlier we start (especially after post-viral loss), the better the chances of full recovery.