MSD Manual

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Some Causes and Features of Anosmia

Some Causes and Features of Anosmia

Cause

Common Features*

Tests

Blockage within the nose

In people who have chronic allergy symptoms (such as nasal congestion and a clear discharge)

No pain

Symptoms that often occur during certain seasons or after exposure to specific substances

A doctor's examination

Polyps that are usually seen during the examination

A doctor's examination

Destruction of smell receptors

A thick, foul-smelling nasal discharge most or all of the time

Previous sinus infections

A doctor's examination

Usually computed tomography (CT)

Coronavirus disease 2019 (COVID-19)†

Loss of smell is often followed by other symptoms of infection (for example, fever or cough)

Viral testing when available

Some viral upper respiratory infections (such as influenza)

Loss of smell that occurs after an infection

A doctor's examination

Tumors (a rare cause)

Possibly vision problems or only loss of smell

CT

Magnetic resonance imaging (MRI)

Drugs (such as amphetamines, enalapril, estrogen, naphazoline, phenothiazines, and reserpine or use of decongestants for a long time)

Usually in people who report taking such drugs

A doctor's examination

Toxins (such as cadmium and manganese)

Usually in people who report exposure to such toxins

A doctor's examination

Destruction of olfactory pathways in the brain

Progressive confusion and loss of recent memory

MRI

Sequential memory tests

In people who have had a head injury

CT or MRI

Degenerative neurologic disorders (such as multiple sclerosis)

Intermittent episodes of other symptoms of nervous system dysfunction, such as weakness, numbness, or difficulty speaking, seeing, or swallowing

MRI

Sometimes a spinal tap

Brain surgery or infection

In people who have had brain surgery or a brain infection

CT or MRI

Sometimes headache and/or symptoms of nervous system dysfunction

CT or MRI

* Features include symptoms and results of the doctor's examination. Features mentioned are typical but not always present.

† Destruction of smell receptors has not yet been confirmed as the mechanism for anosmia.