Anosmia (Loss of Smell)
Reduced or absent sense of smell
Quick Facts
- Type: Sensory (smell) disorder
- Common causes: Nasal congestion, viral infections
- Related sense: Often dulls taste as well
- Often reversible: Many cases improve over weeks to months
Overview
Anosmia is the loss of the sense of smell. It can be complete, where no odors are detected, or partial (called hyposmia), where smell is reduced. The loss may be temporary, such as during a heavy cold, or long-lasting when the smell pathway is damaged.
Because flavor depends heavily on smell, people with anosmia often notice that food tastes bland even though the tongue still detects basic tastes like sweet and salty. Beyond enjoyment of food, smell also serves an important safety role by warning of smoke, gas leaks, and spoiled food, so losing it has real day-to-day consequences.
Symptoms
The central feature is an inability to detect odors, which may be noticed gradually or suddenly. Associated experiences include:
- Food tasting flat or bland despite a normal appetite
- Not being able to smell familiar scents such as coffee, perfume, or smoke
- Difficulty noticing one's own body odor or whether food has spoiled
- In some cases, distorted smells (parosmia) where ordinary odors smell unpleasant
When smell loss is sudden and not explained by a blocked nose, or comes with other neurological symptoms, it should be evaluated promptly.
Causes
Smell loss happens when odors cannot reach the smell receptors high in the nose, or when those receptors or their nerve connections are damaged. Common causes include:
- Nasal and sinus conditions: Congestion from colds, allergies, sinus infections, and nasal polyps that block airflow.
- Viral infections: Some viruses, including those causing the common cold and COVID-19, can damage smell receptors.
- Head injury: Trauma can shear the delicate smell nerves.
- Aging: Smell naturally fades with age.
- Neurological conditions: Early Parkinson disease and Alzheimer disease can reduce smell.
Less commonly, certain medications, chemical exposures, and tumors affect smell.
Risk Factors
- Frequent sinus infections, allergies, or nasal polyps
- Recent viral illness, including upper respiratory infections
- Older age
- Head injuries
- Smoking, which dulls the sense of smell
- Exposure to certain industrial chemicals
Diagnosis
Evaluation aims to find why smell is reduced. A clinician may:
- Ask about the timing, recent illnesses, head injury, and medications
- Examine the inside of the nose, sometimes with a small scope, to look for congestion or polyps
- Use scratch-and-sniff or other standardized smell tests to measure the degree of loss
- Order imaging such as a CT or MRI scan when nerve damage or a structural cause is suspected
Treatment
Treatment depends on the cause. Smell often returns when a reversible problem is corrected:
- Treating nasal blockage: Steroid sprays, allergy treatment, or surgery for polyps can restore airflow.
- Clearing infection: Smell frequently recovers as a cold or sinus infection resolves.
- Smell training: Regularly sniffing a set of distinct scents over weeks to months may aid recovery after viral loss.
- Stopping smoking: Quitting can improve smell over time.
When smell loss results from permanent nerve damage, recovery is less certain, and care focuses on safety, such as installing smoke and gas detectors.
Prevention
- Treat allergies and sinus problems promptly
- Avoid smoking and secondhand smoke
- Protect the head during sports and while driving
- Use protective equipment around strong chemical fumes
- Install smoke and natural-gas detectors if your smell is already reduced
When to See a Doctor
See a doctor if your sense of smell is reduced or lost for more than a couple of weeks, or if it comes on suddenly without a blocked nose. Seek prompt care if smell loss occurs alongside:
- A recent significant head injury
- New confusion, weakness, vision changes, or trouble walking
- Persistent one-sided nasal blockage or bleeding
Frequently Asked Questions
Why does food taste bland when I can't smell?
Most of what we experience as flavor actually comes from smell. When smell is lost, the tongue still senses sweet, salty, sour, and bitter, but the rich aroma that gives food its character is missing, so meals taste flat.
Will my sense of smell come back?
Often, yes. Smell loss from a cold, congestion, or sinus problem usually returns once the cause clears. Recovery after viral infection or nerve injury is less predictable and can take weeks to months, and some loss may be permanent.
Can smell training help?
Smell training, which involves deliberately sniffing a set of distinct scents twice a day over several weeks to months, may help some people regain smell after a viral illness. It is safe and inexpensive to try.
Is sudden loss of smell dangerous?
Sudden smell loss is most often from a viral infection and is not dangerous by itself, but it can be a safety concern because you may not smell smoke, gas, or spoiled food. Sudden loss with head injury or new neurological symptoms should be evaluated promptly.
Does smoking affect smell?
Yes. Smoking dulls the sense of smell over time. Quitting often leads to gradual improvement, though it may take a while.
References
- National Institute on Deafness and Other Communication Disorders (NIDCD). Smell Disorders.
- Mayo Clinic. Loss of smell (anosmia).
- MedlinePlus, U.S. National Library of Medicine. Smell — impaired.