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A Change in Smell After COVID-19 Infection: What You Need to Know

Being able to taste and smell are essential parts of enjoying everyday life. But for some COVID-19 long haulers, these senses can become extremely unpleasant. Some people experience a change to their taste and smell following COVID-19 infection, also known as parosmia (abnormal sense of smell), hyposmia (decreased sense of smell), and anosmia (loss of sense of smell). The good news is it's usually only temporary—in most cases. However, no matter how long these conditions last, it can be very disruptive.

Kristine Smith, MD, a rhinologist and assistant professor in the Division of Otolaryngology (Head and Neck Surgery) at University of Utah Health, answers eight questions about parosmia.

How is parosmia associated with COVID-19?

While it's not known exactly what triggers parosmia, smell disruption can be caused by viral illnesses such as the common cold or influenza. Head trauma, medications, and neurologic diseases such as Parkinson's and other neurodegenerative diseases can also cause parosmia. During a viral illness, the nerve receptors in your nose can be damaged and change your perception of smell. It's believed this same phenomenon occurs during COVID-19 infection.

How are COVID-19 long haulers experiencing parosmia?

A loss of taste and smell is a common symptom of COVID-19 infection. In the recovery phase of COVID-19, a patient normally regains their senses back. However, some people experience a change to their sense of smell about three to four months following infection. People report certain things—like food or body odor—smelling like garbage, rotten eggs, or chemicals. This altered sense of smell is called parosmia.

How common is parosmia?

The number of patients who experience a loss of smell and taste during or after COVID-19 infection ranged widely. The loss or change of taste and smell during COVID-19 infection impacts about 50-75 percent of people. About 25-75 percent go on to develop parosmia in the recovery phase of COVID-19.

When will I get my sense of smell and taste back?

Patients usually improve slowly with time. About 65 percent of people with COVID-19-induced parosmia or hyposmia regain these senses by about 18 months, while 80-90 percent regain these senses by two years.

Who is more likely to develop parosmia?

If you lose your sense of smell or have a reduction in your sense of smell while you have COVID-19, you are more likely to develop a disturbance in your sense of smell later. But you can still experience parosmia even if you didn't originally have smell loss. Patients who are younger and female also seem to have a higher incidence of experiencing post-COVID-19 smell disruption. It's unclear why these groups are more impacted.

Are people still experiencing parosmia with different COVID-19 variants?

The number of people reporting parosmia seems to be changing with COVID-19 variants over time. More cases of parosmia were reported at the beginning of the pandemic with the original SARS-CoV-2 virus. While patients are still experiencing parosmia, the number of patients seeking help with their symptoms is less with the newer variants.

Can parosmia be treated?

There are no guaranteed treatments for post-COVID-19 parosmia. However, some therapies may help some patients. These include:

  • Olfactory retraining is the process of retraining your nose to smell. It involves smelling strong scents (citrus, cloves, eucalyptus) every day while thinking about what they smell like to try to help reform normal responses to your nose and brain. Research has shown it can improve parosmia in long COVID patients. It often takes about 6 to 12 weeks to notice an impact and up to 24 weeks for maximal impact.
  • Intranasal steroids (fluticasone or mometasone) are low-risk nasal spray therapies. Studies have shown that these therapies can improve sense of smell in about 10-25 percent of patients.
  • High-volume saline irrigations or sinus rinses (Neilmed, Netipot, Navage) help improve inflammation in the nose after an infection and may improve recovery after infection.
  • Neuromodulating medications alter the way nerve cells send signals. Limited research has shown some improvements in olfactory dysfunction. These medications, such as gabapentin and amitriptyline, are also used to control chronic pain or headaches. Due to side effects, they are mostly used in patients with severe symptoms.
  • Lifestyle modifications can help improve a patient's quality of life, such as:
    • Eating simpler or bland meals: The more complex the aroma, the more likely it seems to trigger parosmia.
    • Eating food cold or at room temperature: Steam is what carries that sense of smell to your nose, which can trigger parosmia.

Other therapies like stellate ganglion blocks, alpha-lipoic acid, and plasma-rich plasma (PRP) injection are being investigated as potential treatments for COVID-induced parosmia. The risks or potential benefits are not yet known.

Home or natural therapies are becoming increasingly common, but DO NOT try these without talking to your doctor first. What you put in your nose could be absorbed in your bloodstream, which could potentially be dangerous to your health.

Can parosmia be dangerous to your health?

Losing your sense of smell or having a change in your sense of smell is not going to directly cause you harm, but it can increase your risk of some potentially harmful things, such as:

  • Food poisoning: When your sense of smell comes back wrong or is decreased long-term, it can put you at risk of experiencing food poisoning because you may not be able to tell when something in your fridge has gone bad. People with parosmia should pay attention to expiration dates and labeling leftovers.
  • Smoke or natural gas: A person with parosmia may not be able to detect smoke or natural gas in their home. It's important to ensure you have up-to-date smoke and natural gas detectors in your home. If you have a natural gas stove, you may want to consider getting a handheld natural gas detector.
  • Mental health: The ability to smell and enjoy food is really important to our well-being. These types of alterations can significantly impact someone's quality of life. Having persistent parosmia can potentially increase the risk for anxiety and depression. It's important to seek help to treat those associated issues.