What is the treatment for a chronic lack of smell (anosmia)?

Treatment of Chronic Anosmia

For chronic anosmia, implement olfactory training as the primary evidence-based intervention, continuing for at least 3-6 months, while simultaneously addressing any underlying treatable causes such as chronic rhinosinusitis with intranasal corticosteroids or surgical intervention for obstructing polyps. 1, 2, 3

Initial Diagnostic Approach

The first step is determining the underlying etiology, as this directly impacts treatment strategy and prognosis 2, 3:

• Post-viral anosmia (including COVID-19): Most common cause in patients without nasal obstruction symptoms; recovery rates vary from 13-73% depending on the cohort, with mean improvement time of 7.2 days for acute cases, though chronic cases may persist 4
• Chronic rhinosinusitis: The most treatable form of olfactory dysfunction; look for nasal obstruction, discharge, and facial pressure 3, 5, 6
• Medication-related: Review all medications, particularly intranasal antihistamines which commonly cause taste/smell disturbances 1, 3
• Post-traumatic: History of head injury with immediate onset 2, 3
• Neurodegenerative disease: Gradual onset with other neurological symptoms 2

Perform nasal endoscopy to identify polyps, masses, or inflammatory changes that may be surgically correctable 3, 5. Formal olfactory testing with validated instruments (e.g., UPSIT) establishes baseline severity 4.

Treatment Algorithm by Etiology

Post-Viral Anosmia (Including COVID-19)

Olfactory training is the cornerstone intervention 1:

• Begin immediately and continue for minimum 3-6 months 1
• Involves systematic exposure to distinct odors (typically rose, eucalyptus, lemon, clove) twice daily 1
• Recovery data from COVID-19 studies show 44-73% improvement rates, though chronic cases beyond 3-6 months have less favorable prognosis 4

Supportive measures 1:

• Refer to registered dietitian for dietary counseling and flavor enhancers to maintain nutrition 1
• Install smoke detectors and gas alarms for safety 1
• Counsel on checking food expiration dates vigilantly 1

Chronic Rhinosinusitis-Related Anosmia

This represents the most treatable form of olfactory dysfunction 3, 5:

First-line therapy 6:

• Intranasal corticosteroids (primary treatment) 6
• Nasal saline irrigation 6

Second-line therapy 6:

• Systemic corticosteroids for acute exacerbations 6
• Surgical excision of obstructing polyps or masses 3, 5

Emerging biologic therapies for CRS with nasal polyps (CRSwNP) 6:

• Dupilumab, omalizumab, and mepolizumab target type 2 inflammation and have demonstrated smell improvement in randomized controlled trials 6

Important caveat: While treatment improves olfactory function in chronic sinusitis, effects are usually transient and incomplete, requiring ongoing management 5

Medication-Related Anosmia

For intranasal antihistamines causing taste/smell aversion 1:

• Switch to different formulation within same class (olopatadine, azelastine 0.1%, or azelastine 0.15%) as first-line approach 1
• Only switch if symptomatic benefit was achieved despite adverse effects 1

For other medications: Review and discontinue or substitute offending agents when possible 3

Follow-Up Schedule

Structured reassessment is essential 1:

• 1 month: Assess treatment adherence and early response 1
• 3 months: Determine if improvement is occurring 1
• 6 months: If no improvement, refer to otolaryngologist or specialized smell/taste clinic 1

Common Pitfalls to Avoid

• Do not order neuroimaging when there is clear temporal relationship to viral infection or medication use 1
• Do not confuse patient reports of "taste" versus "smell" dysfunction; patients frequently confuse flavor (which requires smell) with taste 3
• Do not overlook safety counseling regarding inability to detect warning odors (gas leaks, smoke, spoiled food) 1, 2
• Do not assume irreversibility in chronic rhinosinusitis cases without attempting medical or surgical intervention, as this is the most responsive etiology 3, 5

Prognosis Considerations

Recovery likelihood varies significantly by cause 4, 2:

• Post-viral (COVID-19): 44-73% show some recovery, though timing is variable and some cases persist beyond 6 months 4
• Chronic rhinosinusitis: Most treatable but often requires ongoing management with incomplete resolution 5
• Post-traumatic and congenital: Generally poor prognosis with limited treatment options 2, 7
• Age-related: Natural decline with advancing age; limited reversibility 2, 3

Quality of life impact is substantial across all etiologies, affecting safety, nutrition, social interactions, and emotional well-being, justifying aggressive management even when complete recovery is unlikely 2, 3, 6.