Anosmia

Anosmia is the complete loss of sense of smell. It may be temporary or permanent and can occur alone or with a diminished sense of taste. It can affect appetite, safety, and quality of life.

Common causes include upper respiratory infections such as colds, nasal obstruction from chronic rhinosinusitis or nasal polyps, allergic rhinitis, and sinonasal diseases; head trauma can damage olfactory nerves; aging is associated with gradual deterioration; exposure to toxins or certain medications can impair smell; viral infections, including SARS-CoV-2, are a well-recognized cause.

Evaluation involves medical history and physical examination, nasal endoscopy, and sometimes imaging. Objective olfactory tests assess detection, discrimination, and identification. Distinguish conductive loss (blocked nasal passages) from sensorineural loss (nerve damage).

Treatment aims at the underlying cause. Inflammatory conditions may respond to nasal corticosteroids; obstruction may require medical or surgical management. Olfactory training, using repeated exposure to a set of odors over several months, has some evidence of benefit. Safety precautions, such as smoke and gas detectors, should be used.

Prognosis varies. Many individuals recover after viral infections or obstruction removal, but some have persistent anosmia. People with persistent anosmia may benefit from referral to an otolaryngologist or an olfactory specialist and participation in smell rehabilitation programs.