Smell (olfactory) disorders can present in many forms: complete loss (anosmia), reduced loss (hyposmia), or change in smell (parosmia or phantosmia). All forms can be quite debilitating and affect 6 million people in the U.S.
Not being able to detect bad smells can be quite troublesome, such as a parent not being able to detect the smell of a dirty diaper, or even dangerous, such as not smelling smoke or natural gas fumes.
The Relationship Between Loss of Smell and Loss of Taste
You’d be surprised how your sense of smell is directly connected to your sense of taste. 80% of taste disorders (ageusia) are from an impaired sense of smell.
When you eat, special chemical substances called aromatics are released and travel from the back of your throat up to your nose. These aromatics stimulate your nose and, coupled with your taste buds, determine how you perceive food.
Causes of Loss of Smell and Taste
Olfactory disorders have many causes, and a specialist such as an ear, nose, and throat (ENT) doctor is typically necessary to sort out the root cause. As a rule, if you have lost your sense of smell for more than two weeks, you should seek a physician to determine the cause.
Nasal Obstruction
The most common cause for loss of smell and taste is simply nasal obstruction, such as from congestion due to a cold or bad allergies. Long-standing nasal obstruction from something like nasal polyps or severe nasal septal deflections can also be a cause of obstruction.
Either way, if your nose is blocked, you won’t be able to get those aromatic particles to reach the top of your nose to stimulate the nerves of olfaction.
Infection
The second most common cause is damage from an infection, especially viruses. Viruses are known to damage all kinds of nerves (especially cranial nerves), including the nerves in the nose used for smell.
After a viral infection, sense of smell typically returns within two weeks, although recovery can vary from weeks to months. Permanent damage to the nerves may also occur.
Coronavirus
The coronavirus that has led to the COVID-19 pandemic has caused an increase in patients losing their sense of smell and taste. Like any virus, the coronavirus attaches to the nasal receptors (specifically the ACE2 receptor) and causes damage.
In our clinic, we’ve found that recovery is often extended to several months post-COVID and is often associated with a temporary phase of parosmia, where your sense of smell or taste changes (oftentimes for the worse).
Additional Causes
Less common causes of olfactory disorders include head trauma (concussions), various nasal and brain masses and tumors, neurodegenerative disorders (dementia), as well as toxin and medicine side effects. In some patients, the cause may simply be unknown.
[Related: What Can Cause Loss of Smell?]
Treatments for Loss of Smell & Taste
In Dr. Pasha’s clinic, several steps are required in the work-up of olfactory issues to formulate a treatment plan, including nasal endoscopy (a painless microscopic evaluation of the nose), allergy testing, and a CT scan (X-ray). All tests can be performed in the office.
Treatment for loss of smell and taste depends on the cause. For example, if you have nasal polyps, then have them removed. If you have a viral infection, you may need to take medications to reduce the inflammation caused by the infection.
For those who have long-standing loss of smell, olfactory training (or smell training) may be beneficial. Dr. Pasha has his own olfactory training regimen that he may provide for you. The future of anosmia management is growing and includes stem cell research and even gene therapy for some congenital causes.
Loss of smell can be frustrating for patients. The key is to spend the time necessary to identify the cause so you can focus your therapy.
