Abnormal Sense of Taste & Smell Causes, Symptoms, Diagnosis, Treatment

Abnormal Sense of Taste & Smell Causes, Symptoms, Diagnosis, Treatment

Smell and Taste Abnormalities


Although abnormal taste sensations may be due to mental disorders, local causes should always be sought. Glossopharyngeal and facial nerve integrity can be determined by testing taste on both sides of the dorsum of the tongue with sugar, salt, vinegar (acid), and quinine (bitter). 

Drying of the oral mucosa caused by heavy smoking, Sjögren's syndrome, radiation therapy of the head and neck, or desquamation of the tongue can impair taste, and various drugs (eg, those with anticholinergic properties and vincristine) alter taste. In all instances, the gustatory receptors are diffusely involved. When limited to one side of the tongue (eg, in Bell's palsy), ageusia (loss of the sense of taste) is rarely noticed.


The inability to detect certain odors, such as gas or smoke, may be dangerous, and several systemic and intracranial disorders should be excluded before dismissing symptoms as harmless. Whether brain stem disease (involvement of the nucleus solitarius) can cause disorders of smell and taste is uncertain, because other neurologic manifestations usually take precedence. 

Anosmia (complete loss of the sense of smell) is probably the most common abnormality. Hyperosmia (increased sensitivity to odors) usually reflects a neurotic or histrionic personality but can occur intermittently with seizure disorders. Dysosmia (disagreeable or distorted sense of smell) may occur with infection of the nasal sinuses, partial damage to the olfactory bulbs, or mental depression. Some cases, accompanied by a disagreeable taste, result from poor dental hygiene. Uncinate epilepsy can produce brief, vivid, unpleasant olfactory hallucinations. Hyposmia (partial loss of smell) and hypogeusia (diminished sense of taste) can follow acute influenza, usually temporarily.

What causes abnormal sense of taste and smell?

The most common causes of smell disorders are nasal and/or sinus disease, viral upper respiratory infections, and head trauma. The most common causes of taste disorders are upper respiratory tract infections and head injuries. Other infrequent causes of both include masses in the nasal or oral passageways, endocrine problems, side effects from medications, and degenerative processes of the brain.

What are the symptoms of abnormal sense of taste and smell?

Abnormal sense of smell can refer to either a decreased or absent sense of smell, smelling odors that are not really present, or the inability to identify odors. These can significantly affect quality of life for a patient, causing anxiety and decreased enjoyment of food. Changes in taste and smell can occasionally be dangerous for patients, such as when you cannot smell smoke or other warning odors.

How are these diseases diagnosed?

The first step in diagnosis is a thorough history and physical examination. It is important to provide information to your doctor regarding respiratory illnesses, nasal or sinus symptoms, history of trauma, other medical conditions, and medication use.

What are the treatments of taste and smell disorders?

Treatments of taste and smell disorders are directed towards the underlying cause. Nasal or sinus conditions should be managed with either medication or surgical therapy, depending on the severity of the disease. Endocrine disorders such as hypothyroidism should be treated appropriately. Medications that may be causing the smell and/or taste disturbance can sometimes be substituted with another medication.