What Can Cause a Loss of Taste and Smell?

What Can Cause a Loss of Taste and Smell?

Do you like to take time to smell the roses, but lately they don’t smell as sweet? Several viruses and conditions, including COVID-19, could be the culprits behind a loss of taste and smell.

A bouquet of flowers. A home-cooked meal. Milk that’s past its best-by date. Our senses of taste and smell help us to detect and catalogue a wide spectrum of flavors and scents. Both can also serve to tell us when something’s not safe to eat. And interestingly, what we perceive as a disruption in our ability to taste may often be rooted in issues related to our sense of smell.

Smell disorders can present different symptoms, including:

  • Hyposmia – a lessened ability to detect odors
  • Anosmia – a complete inability to detect odors
  • Parosmia – a change in the normal perception of scents (e.g., what used to smell pleasant is now foul)
  • Phantosmia – the perception of an odor that is not present

If you’re experiencing issues with your ability to taste and smell, here are some of the conditions that may be at the root of these changes.

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1. Viral infections like the flu, colds and COVID-19

If you’ve had a cold, you may be all too familiar with a stuffy nose that makes it hard to smell. In fact, both the common cold and influenza can cause temporary anosmia. Scientists have also identified a loss of taste and smell among the symptoms associated with COVID-19.

“Viruses can disrupt the nerves related to smell, and they can target the tissues in the nose,” says Elisabeth D. Ference, MD, an otolaryngologist at Keck Medicine of USC and assistant professor of clinical otolaryngology – head and neck surgery at the Keck School of Medicine of USC. “The viruses can cause inflammation, either to the nerve or to the lining of the nose, that impacts the normal function of our sense of smell.”

When smell is lost, often taste is, too. “Approximately 80% of the flavors we taste come from our sense of smell, so if our nerves related to smell are not working, then we also have an impairment in our sense of taste,” Ference explains. “Taste that is sensed on the tongue — salty, sweet, sour and bitter — will still be present. However, the subtlety of food, such as oregano on pizza, will be lost.”

2. An early sign of neurological conditions

Smell and taste are processed through the brain, so it might not be surprising that conditions affecting the brain, like Parkinson’s disease or Alzheimer’s disease, are linked to disruptions or a loss of these senses, especially smell.

“Neurological or nervous system conditions such as Parkinson’s disease may affect smell by impacting the olfactory bulb, the part of the brain where the smell nerves come from. Therefore, loss of smell can be an early sign of the disease,” Ference says.

It’s important to note that just because you’re experiencing a loss of smell doesn’t mean you will develop Parkinson’s.

“Not all patients who lose their sense of smell will eventually develop a neurologic or nervous system disease,” Ference explains. “The olfactory bulb can be damaged by trauma and other causes, while the nerves themselves can be affected by viruses and several other factors.”


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3. Nasal polyps

If you’re prone to frequent sinus infections, you may develop nasal polyps, benign growths in the nose.

Nasal polyps and chronic sinus disease affect smell because they lead to inflammation of the lining of the nose, which prevents odor molecules from reaching the smell nerves,” Ference says.

Treatment may include topical medications such as steroid sprays and nasal saline rinses that shrink the polyps. In some cases, surgery may also be performed.

“Often, if the inflammation in the nose is controlled, the patient will have a full return of their sense of smell, since neither the smell nerves nor the brain are impacted,” Ference explains.

4. Age

According to the National Institutes of Health, up to one in four Americans over the age of 40 may experience changes in their sense of smell; that number increases to nearly one in three for people over the age of 80. When it comes to taste, one in five Americans may experience changes after they turn 40.

As we age, several factors can contribute to a loss of taste and smell, including dental issues, dry mouth, certain medications, alcohol consumption and smoking. In addition, less mucus production in the nose, a loss of nerve endings and changes in the taste buds can occur as we age, affecting smell and taste.

If you’re experiencing a loss of taste and smell, talking to your primary care physician or visiting an otolaryngologist, a doctor who specializes in the conditions of the ear, nose and throat, may help you pinpoint what’s causing these changes in your senses.

by Tina Donvito

Are you experiencing a loss of smell or taste? Our otolaryngology specialists at Keck Medicine can help. If you are in the Los Angeles area, request an appointment or call (800) USC-CARE (800-872-2273).

2020-06-12T10:24:28-07:00Blog, Ear Nose and Throat|