Smell Loss After Upper Respiratory Infection

Losing the sense of smell is not uncommon with upper respiratory infections (URI), typically with a viral common cold or flu. According to some studies, smell loss or decrease may occur between 18-45% of  patients who suffer from a URI.

It is estimated that about 1/3 of such patients will fully recover their sense of smell with 2-3 years, most within the first year. Unfortunately, that leaves 2/3 of these patients who suffer from some degree of smell dysfunction.

The key determining factor whether full recovery is expected or not is whether there is still some smell sense present (hyposmia). Those with COMPLETE smell loss (anosmia) have a much higher risk of no recovery.

A secondary factor to predicting whether full smell recovery will happen or not is age. The older the patient's age, the worse potential for smell recovery.

In terms of treatment, literature reports that steroids, vitamin B, zinc, theophylline, and α-lipoid acid can be used to treat post-infectious olfactory loss, but thus far there is no definitive effective therapy available to date.

In spite of smell and taste dysfunction being relatively common complaints, there's only a few centers that actively evaluate and treat patients with these complaints.

In our area, there's only two...

Taste and Smell Clinic in Washington DC

VCU Smell and Taste Disorders Center in Richmond, VA

References:

Postinfectious olfactory loss: A retrospective study on 791 patients. The Laryngoscope, 128: 10–15. doi:10.1002/lary.26606

Complaints of olfactory disorders: epidemiology, assessment and clinical implications. Curr Opin Allergy Clin Immunol 2008;8:10–15.

Smell and taste disorders, a study of 750 patients from the University of Pennsylvania Smell and Taste Center. Arch Otolaryngol Head Neck Surg 1991;117:519–528.

Olfactory dysfunctions. Epidemiology and therapy in Germany, Austria and Switzerland [in German]. HNO 2004;52:112–120.

Postviral olfactory loss. Otolaryngol Clin North Am 2004;37:1159–1166

Characteristics of olfactory disorders in relation to major causes of olfactory loss. Arch Otolaryngol Head Neck Surg 2002;128:635–641.

Long-term follow-up of olfactory loss secondary to head trauma and upper respiratory tract infection. Arch Otolaryngol Head Neck Surg 1995;121:1183–1187.

Local and systemic administration of corticosteroids in the treatment of olfactory loss. Am J Rhinol 2004;18:29–33.

Topical therapy in anosmia: relevance of steroid-responsiveness. Laryngoscope 2008;118:1681–1686.

Lipoic acid in the treatment of smell dysfunction following viral infection of the upper respiratory tract. Laryngoscope 2002;112:2076–2080.