Altered smell refers to changes in the sense of smell, including complete loss, reduced sensitivity, distorted perception of familiar odors, or sensing odors that are not present. This page outlines typical causes, how clinicians approach evaluation, and which specialties may be involved. It is general information and not a substitute for personalized medical assessment.
What altered smell means
Changes in smell can present as anosmia (no smell), hyposmia (reduced smell), parosmia (existing smells perceived differently), or phantosmia (smelling things that are not there). Symptoms may be temporary or persistent and can affect one or both nostrils.
Common causes and how they affect smell
Frequent causes include viral upper respiratory infections, chronic sinus disease and nasal polyps, allergic rhinitis, head trauma, and age-related decline. Neurological conditions and environmental exposures (toxins) can also alter smell by affecting receptors, neural pathways, or airflow to the olfactory region.
How clinicians evaluate altered smell
Assessment usually begins with medical history and a focused ENT examination, possibly including nasal endoscopy. Objective smell tests help quantify deficits. Blood tests and imaging (CT or MRI) are used selectively to examine sinuses or neurological structures. Neurology or infectious disease consultation may be recommended if other neurologic or systemic signs are present.
Which specialists to see and when
Initial assessment is commonly done by a primary care clinician or Ear, Nose and Throat (ENT) specialist. Depending on findings, referrals may include Neurology, Infectious Diseases, or Allergy/Immunology. Sudden loss of smell accompanied by severe headache, vision change, weakness, difficulty speaking, or breathing/swallowing problems should prompt urgent evaluation.