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Is Loss of Smell a Symptom of COVID-19?

Published on Apr 01, 2020 and last reviewed on Jan 06, 2022   -  5 min read

Abstract

Doctors have noted that coronavirus (COVID-19) patients exhibit loss of taste much before they develop cough, fever, and breathing problems. Read the article to know more.

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Is Loss of Smell a Symptom of COVID-19?

Is Loss of Smell a Symptom of COVID-19?

According to the World Health Organization (WHO), the symptoms of novel coronavirus disease (COVID-19) during the onset of the pandemic were dry cough, fever, runny or stuffy nose, fatigue, and dyspnea (shortness of breath). But as months passed by, evidence from around the globe suggested that loss of smell and taste were also symptoms of COVID-19. A significant number of coronavirus patients in South Korea, China, and Italy had developed anosmia (loss of smell), ageusia (loss of taste), and hyposmia (reduced ability to smell). The British Association of Otorhinolaryngology stated in an online post that a large number of coronavirus-infected patients who did not show any other symptoms had a loss of taste and smell. Statistics showed that there was a sudden rise in cases of a partial or total loss of smell in the UK, France, the US, and Italy. This made scientists and researchers explore more about the link between loss of taste and smell and coronavirus. Finally, they concluded that loss of smell was a notable symptom in most people with COVID. Eventually, it became one of the common symptoms of COVID.

Why Are People Reporting a Loss of Taste Along With Smell?

It is important to note that we smell and taste food together when we eat. If you pinch your nose and then eat, you will notice that the only things you can perceive are if the food is salty, sour, sweet, savory, and bitter, as these elements come from the taste buds present on the tongue. You will not exactly be able to appreciate the essence and flavor of what you are eating. This is why most people who lose the sense of smell also think that their sense of taste is lost.

The other strains of coronaviruses, that resulted in SARS and MERS, were also responsible for causing 10 to 15 % of anosmia cases, which is why researchers are not surprised that the novel COVID-19 virus can also result in similar symptoms.

How Is the Sense of Smell Affected?

Usually, the viruses that cause common colds and the flu result in nasal congestion, nasal obstruction, edema of the nasal mucosa, and excess nasal secretions, resulting inloss of smell. But in the case of COVID, it was found that the sustentacular cells in the olfactory epithelium express two entry proteins, ACE 2 and TMPRSS 2, in abundance. The SARS-CoV-2 targets these entry proteins and causes damage to these sustentacular cells. But these sustentacular cells are found to rapidly get replenished, which is why the temporary loss of smell is regained within a week’s time. To date, it is believed that an inflammation-mediated loss of odorant receptor expression could be the possible cause for anosmia in COVID.

Loss of smell and taste due to a viral infection usually is temporary, and the patient regains these senses once he or she recovers. Only around 1 % of patients suffer from persistent anosmia and ageusia.

What to Do If You Experience Smell or Taste Loss?

If you have a sudden loss of smell and taste and if you feel you might have contracted the virus in the past couple of weeks, you should self-isolate. And wait and watch for any other symptoms for the next 14 days. Also, ask your family members to stay at home for 2 weeks.

Avoid using oral steroids to treat these symptoms, as it is believed that oral steroids can exacerbate the underlying viral infection. You may use nasal steroids after consulting a doctor first.

COVID-19 Patients and Damaged Sense of Smell (Parosmia):

Many recovered COVID-19 patients are now reporting that certain food items smell and taste awful. This temporary condition that distorts odors, making them unpleasant, is called parosmia. While the patient can at least smell something after a complete loss of smell and taste, it indicates that these senses are returning. But, parosmia can last for long periods and can make foods like coffee, eggs, fried foods, and chocolate intolerable. Some patients also report smelling odors that are not there, like sewage, rotten food, and cigarette smoke. This distortion is called phantosmia.

This can be frustrating for recovering patients, as the food they once loved might smell revolting. A report published by the Global Consortium for Chemosensory Research stated that out of 4,000 COVID-19 patients, 7% had a distortion in their sense of smell. But this finding is not surprising as parosmia and phantosmia usually occur after viral infections. Doctors believe that parosmia due to COVID-19 is actually a good sign because it indicates that your olfactory tissues are regenerating and returning to normal.

What Should Doctors Do?

As anosmia was commonly seen in patients who tested positive and are otherwise asymptomatic, it was finally included in the early symptoms of coronavirus.

If your patient complains of anosmia and ageusia, and-

Then the best thing to do would be to test the patient for the virus. But if the healthcare guidelines at your place recommend testing only if the patient has a fever, cough, and shortness of breath, you can advise the patient to self-isolate for at least 14 days, and to report back in case he or she develops shortness of breath or fever.

How Common Are Anosmia and Ageusia Reported as Symptoms of COVID-19?

Based on different study estimates and demographics, it is said that around 20 to 50 % of the population worldwide express anosmia as an early sign of COVID. It is especially common among young COVID patients when compared to older patients. Also, anosmia is prevalent in asymptomatic individuals though it can occur in symptomatic individuals too. Unlike the common cold, flu, and sinusitis, COVID anosmia can happen in the absence of nasal congestion.

If Not COVID-19, What Are the Other Causes of Anosmia?

Apart from COVID-19, there are other causes for anosmia which could be causing you loss of smell in this pandemic, such as,

  1. Nasal Mucous Membrane Irritation:

    1. Sinusitis.

    2. The common cold.

    3. The flu.

    4. Allergic rhinitis.

    5. Smoking.

  2. Nasal Passages Blockage:

    1. Nasal tumors and polyps.

    2. Deviated nasal septum.

  3. Brain or Nerve Disorders or Damage:

    1. Aging.

    2. Head injury.

    3. Hormonal imbalance.

    4. Medications such as antibiotics and antihypertensives.

    5. Alzheimer’s.

    6. Brain tumors.

    7. Multiple sclerosis.

    8. Parkinson’s.

    9. Epilepsy.

    10. Brain surgery.

    11. Stroke.

    12. Schizophrenia.

    13. Diabetes.

    14. Congenital anosmia (babies born without the sense of smell)

    15. Chemical injury to the nose.

    16. Malnutrition.

    17. Radiotherapy.

    18. Alcoholism.

Can Anosmia Be Treated?

If the cause of anosmia is a cold, COVID, sinus infection, or allergy, it usually gets better on its own in a few days. In case it does not, then it is better to consult a doctor. The doctor might prescribe decongestants, antihistamines, steroid nasal sprays, or antibiotics (if it is a bacteria infection).

If the cause is nasal obstruction, then the doctor will perform a procedure to straighten the nasal septum or remove nasal polyps.

Loss of smell seen in older people and people with congenital anosmia is unfortunately permanent and cannot be cured.

There are a lot of myths and fake news surrounding the spread and symptoms of coronavirus, so do not believe and act on those without confirming it by a doctor online. Stay home and be safe!

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Last reviewed at:
06 Jan 2022  -  5 min read

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