What is the treatment for anosmia (loss of smell) resulting from a past COVID-19 infection?

Treatment Options for COVID-19-Related Anosmia

Olfactory training is the most strongly recommended first-line treatment for anosmia resulting from COVID-19 infection, with additional therapies such as intranasal corticosteroids considered in persistent cases. 1

Understanding COVID-19-Related Anosmia

Anosmia (loss of smell) is a common symptom of COVID-19 infection, often presenting as an early or even isolated symptom. The pathophysiology appears to involve:

• Inflammation of the olfactory clefts
• Damage to the olfactory epithelium
• Possible involvement of ACE2 receptors on sustentacular cells
• Local inflammation rather than direct neural damage 1, 2

Most patients experience spontaneous recovery within a few weeks, with studies showing:

• Complete resolution in 13-44% of patients
• Partial resolution in 14-16% of patients
• Mean time to improvement of 7.2-7.8 days 1, 3

However, some patients experience persistent anosmia that requires treatment.

Treatment Algorithm for COVID-19-Related Anosmia

First-Line Treatment:

1. Olfactory Training
   • Systematic exposure to different strong odors (e.g., essential oils like rose, eucalyptus, lemon, clove)
   • Practice twice daily for at least 12 weeks
   • Involves sniffing each odor for 10-20 seconds with focus and concentration 1, 2

Second-Line Options (for persistent anosmia):

1. Intranasal Corticosteroids

   • Consider mometasone furoate nasal spray in combination with olfactory training
   • Studies show 62% recovery with combined therapy vs. 52% with olfactory training alone 1
   • Use with caution as early COVID-19 guidelines initially advised against corticosteroids 1

2. Other Potential Therapies (limited evidence):

   • Intranasal insulin (fast-dissolving film) - showed significantly higher olfactory detection scores in one RCT 1
   • Oral supplements (zinc, vitamin A) - limited evidence
   • Sodium citrate nasal spray - limited evidence 2, 4

Important Considerations:

• Timing: Treatment should begin as soon as possible after the acute phase of COVID-19 has resolved
• Duration: Persistent anosmia may require extended treatment (3+ months)
• Safety Precautions: Advise patients about safety concerns related to anosmia:
  • Install gas and smoke alarms
  • Check food expiration dates carefully
  • Be cautious with gas appliances 1

Special Considerations

• Prognosis: Reassure patients that most COVID-19-related anosmia cases resolve spontaneously within 2 weeks (97% in one study) 3
• Associated Symptoms: Ageusia (loss of taste) frequently accompanies anosmia (66% of cases) 3
• Quality of Life Impact: While not life-threatening, persistent anosmia significantly decreases quality of life and should be addressed proactively 5

Common Pitfalls to Avoid

1. Delayed Treatment: Don't wait too long to begin olfactory training; earlier intervention may improve outcomes
2. Inappropriate Imaging: Routine imaging is not recommended unless other neurological symptoms are present
3. Overlooking Comorbidities: Underlying conditions like type 2 diabetes or rhinitis may influence recovery 6
4. Inadequate Duration: Olfactory training requires persistence; patients should continue for at least 12 weeks even if initial improvement is slow

Olfactory training remains the cornerstone of treatment with the strongest evidence base, while additional therapies may be considered for persistent cases under appropriate medical supervision.