The senses of taste and smell are closely related in terms of the proximity of the receptors in the nose and mouth and the anatomical sites in the brain where these sensations are perceived and interpreted. The co-existing loss of taste and smell most often occurs due to a malfunction in the sense of smell that secondarily disrupts taste sensations. A variety of disorders and conditions can cause transient or permanent disruptions in the senses of taste and smell.
Nasal Congestion
Nasal congestion associated with head colds, allergies and sinusitis remains among the leading causes of decreased smell and taste sensations, reports Dr. Steven Bromley in a January 2000 article published in "American Family Physician." With these conditions, mucus overproduction and blocked airflow limit the transmission of inhaled aromatic chemicals to the nasal smell receptors, leading to decreased odor sensitivity. Taste distortions arise due to the disruption in aromatic sensory input. Resolution of the underlying nasal congestion typically leads to restoration of fully functional smell and taste sensations.
Head Trauma
Head trauma proves a frequent cause of a decreased sense of smell with an associated loss in taste acuity. Ear, nose and throat specialist William Harrill, M.D., reports in the Grand Round Archives of the Baylor College of Medicine's Department of Otolaryngology--Head and Neck Surgery that the risk for a traumatic disruption in the sense of smell correlates with the severity of the head injury. Head trauma may cause tearing of the delicate nerve fibers that transmit aroma signals from the nose to the brain, resulting in a partial or complete loss of the sense of smell.
Medications
A variety of medications may cause disturbances in the sense of smell, reports the National Institute on Deafness and Other Communication Disorders. Decreased or distorted taste often accompanies medication-induced loss of smell.
In his "American Family Physician" article, Bromley points out several medications associated with a loss of the sense of smell, including certain antibiotics, such as azithromycin, ofloxacin, ampicillin, ciprofloxacin and tetracycline; antidepressants, such as doxepin, nortriptyline, amitriptyline and imipramine; heart and blood pressure medications, including captopril, enalapril, acetazolamide, propranolol, nifedipine and hydrochlorothiazide; the decongestant pseudoephedrine; the allergy medications loratidine and chlorpheniramine; corticosteroids, such as hydrocortisone and dexamethasone; and anticancer drugs, including methotrexate, cisplatin, vincristine and doxorubicin.
Notably, in 2009, the U.S. Food and Drug Administration issued a public health advisory warning the public of a significant risk for loss of the sense of smell associated with the use of over-the-counter, zinc-containing nasal sprays. The FDA recommended that the public stop using the products and discard them. Oral zinc was not implicated in the advisory.
References
- American Family Physician: Smell and Taste Disorders: A Primary Care Approach
- Baylor College of Medicine Department of Otolaryngology--Head and Neck Surgery: Anosmia
- National Institute on Deafness and Other Communication Disorders: Smell Disorders
- U.S. Food and Drug Administration: Warnings on Three Zicam Intranasal Zinc Products
- American Academy of Otolaryngology--Head and Neck Surgery: Smell and Taste
