Lost or changed sense of smell

Lost or Changed Sense of Smell (Anosmia, Hyposmia, or Parosmia)

Loss or alteration of the sense of smell can occur suddenly or gradually and may be temporary or permanent. It is a symptom that significantly affects quality of life, appetite, and overall well-being.

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Causes

• Infections

  • Viral upper respiratory tract infections (common cold, influenza, COVID-19).

  • Sinus infections causing swelling and blockage of nasal passages.

• Nasal and sinus problems

  • Nasal polyps, deviated septum, allergic rhinitis, chronic sinusitis.

  • Swelling prevents odor molecules from reaching the olfactory receptors.

• Neurological conditions

  • Alzheimer’s disease, Parkinson’s disease, multiple sclerosis.

  • Traumatic brain injury affecting the olfactory nerves.

  • Brain tumors involving the olfactory bulb or frontal lobe.

• Medication-related causes

  • Antibiotics (clarithromycin, amoxicillin–clavulanate).

  • Antihypertensives (nifedipine, enalapril).

  • Antidepressants (SSRIs, tricyclics).

  • Chemotherapy agents.

• Lifestyle and environmental causes

  • Smoking or long-term exposure to toxic chemicals.

  • Aging (natural decline in olfactory sensitivity).

• Other causes

  • Hormonal changes (pregnancy, hypothyroidism).

  • Vitamin B12 or zinc deficiency.

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Symptoms Associated

• Complete loss of smell (anosmia).

• Reduced sense of smell (hyposmia).

• Distorted or unpleasant smell perception (parosmia, phantosmia).

• Taste changes, since smell contributes heavily to flavor perception.

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Evaluation

• History and physical exam to identify onset, duration, and associated symptoms.

• Nasal endoscopy for structural or inflammatory issues.

• CT or MRI scan if a neurological cause is suspected.

• Olfactory function tests in specialized centers.

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Treatment

• Underlying cause treatment

  • Viral infections: Usually resolve spontaneously.

  • Allergies: Antihistamines (loratadine, cetirizine), intranasal corticosteroids (fluticasone, mometasone).

  • Nasal polyps: Intranasal steroids, surgery if needed.

  • Bacterial sinusitis: Antibiotics such as amoxicillin–clavulanate.

  • Nutritional deficiency: Zinc or vitamin B12 supplementation.

• Neurological causes

  • Symptom management, as recovery may be limited in degenerative disorders.

• Medications sometimes prescribed

  • Corticosteroids (oral prednisone in short courses) for severe inflammation.

  • Saline nasal sprays to keep nasal passages moist.

• Non-pharmacological management

  • Olfactory training: Repeated exposure to strong scents (e.g., lemon, rose, clove, eucalyptus) for months has shown benefit in some patients.

  • Avoidance of irritants such as smoke and strong chemicals.

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When to Seek Medical Help

• Sudden, complete loss of smell (especially linked with COVID-19).

• Persistent loss lasting more than 2–3 weeks.

• Accompanied by severe headache, vision changes, or neurological symptoms.

• Associated with blood-stained nasal discharge (possible tumor).

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Medications (Generic Names and Typical Doses)

• Fluticasone nasal spray: 50 mcg per spray, 1–2 sprays in each nostril once daily.

• Mometasone nasal spray: 50 mcg per spray, 2 sprays in each nostril once daily.

• Prednisone (short course, for severe inflammation under supervision): 30–40 mg orally once daily, tapered over 5–7 days.

• Cetirizine: 10 mg orally once daily for allergies.

• Loratadine: 10 mg orally once daily for allergies.

• Amoxicillin–clavulanate: 875/125 mg orally every 12 hours for 7–10 days (for bacterial sinusitis).

• Vitamin B12 (cyanocobalamin): 1000 mcg orally daily or intramuscularly monthly, if deficient.

• Zinc sulfate: 220 mg orally once daily, if deficient.