What are the causes and clinical manifestations of taste disorders?

Abnormal taste can generally be caused by oral mucosal lesions, neurological disorders, endocrine imbalances, drug side effects, nutritional deficiencies, and other factors. Clinically, it typically manifests as hypogeusia (reduced taste), taste hypersensitivity, dysgeusia (distorted taste), ageusia (complete loss of taste), or oral malodor accompanying taste disturbances. A detailed analysis is as follows:

I. Etiology

1. Oral Mucosal Lesions: Inflammation, ulcers, fungal infections, and other oral mucosal conditions may damage taste buds and surrounding tissues, impairing taste signal transmission. This often leads to abnormal taste perception and is commonly seen in individuals with gingivitis or recurrent oral ulcers.

2. Neurological Disorders: Cerebrovascular diseases, neuritis, Parkinson’s disease, and similar conditions can damage neural pathways related to taste—such as the glossopharyngeal and facial nerves—preventing normal transmission of taste signals to the brain, thereby causing taste abnormalities.

3. Endocrine Imbalances: Endocrine disorders such as diabetes mellitus and thyroid dysfunction can disrupt metabolic processes, alter saliva composition and secretion, and consequently impair the taste buds’ ability to perceive flavors, leading to taste disturbances.

4. Drug Side Effects: Certain antibiotics, antihypertensive medications, and antidepressants may affect taste receptor function or reduce saliva production, resulting in taste abnormalities. Symptoms usually improve gradually after discontinuation of the medication.

5. Nutritional Deficiencies: Deficiencies in vitamin B complex, zinc, iron, and other nutrients can impair the growth and regeneration of taste bud cells, reducing taste sensitivity and causing hypogeusia or distorted taste. This is commonly observed in individuals with unbalanced diets.

II. Clinical Manifestations

1. Hypogeusia (Reduced Taste): Decreased ability to perceive basic tastes such as sweet, sour, bitter, and salty. Food may seem bland during meals, requiring stronger flavors for detection. Severe cases may reduce appetite and interest in eating.

2. Taste Hypersensitivity: Excessive sensitivity to certain tastes; even mild sweetness or sourness may cause strong discomfort, nausea, or oral pain. This is commonly found in individuals with sensitive oral mucosa or neurological abnormalities.

3. Dysgeusia (Taste Distortion): Misinterpretation of taste sensations—for example, perceiving sweetness as bitterness or sourness as saltiness. This results in taste experiences inconsistent with the actual flavor of food, interfering with normal dietary judgment.

4. Ageusia (Loss of Taste): Complete inability to detect basic tastes. During eating, only texture and temperature of food can be perceived, while taste cannot be distinguished. This is often due to severe nerve damage or complete destruction of taste buds.

5. Oral Malodor Accompanying Taste Abnormalities: Presence of persistent unpleasant oral odors—such as bad breath, metallic taste, or bitterness—alongside taste disturbances. These odors persist despite oral hygiene measures and are often associated with oral infections or systemic diseases.

To manage these issues, maintain good oral hygiene through regular cleaning to prevent oral mucosal lesions. If taste disturbances occur after starting a new medication, inform your doctor promptly to evaluate possible adjustments. If taste abnormalities persist for more than two weeks or are accompanied by other symptoms, seek medical evaluation promptly to identify the underlying cause and avoid delayed treatment.