What is anosmia and is it a symptom of COVID-19?

There are many causes of anosmia that EMTs and paramedics regularly encounter


Perhaps you have read somewhere recently that losing your sense of smell may mean you have COVID-19. The American Academy of Otolaryngology- Head and Neck Surgery, released a statement on March 23 suggesting that “anosmia, hyposmia, and dysgeusia” be added to the symptom screening tools for possible COVID-19 infection.

What do these medical terms mean?

  • Anosmia is loss of a sense of smell
  • Hyposmia is reduced ability to smell
  • Dysgeusia is altered sense of taste
Losing your sense of smell does not automatically mean that you have COVID-19. (Photo/Getty Images)
Losing your sense of smell does not automatically mean that you have COVID-19. (Photo/Getty Images)

Currently, there are only anecdotal reports of this symptom presenting in COVID-19 patients; there are no documented studies right now that demonstrate that anosmia is a common symptom of this viral illness.

A report from ENT UK reports that “in Germany, it is reported that more than 2 in 3 confirmed cases have anosmia. In South Korea, where testing has been more widespread, 30% of patients testing positive have had anosmia as their major presenting symptom in otherwise mild cases”. This data, however, is not verified or published at the moment, so it remains purely anecdotal.

We should continue to follow research on anosmia, hyposmia and dysgeusia, however, as these patient-reported symptoms may become a helpful early screening tool for suspected COVID-19 cases.

Other causes of anosmia

Losing your sense of smell does not automatically mean that you have COVID-19. In fact, in an analysis of a national health survey, in adults > 40 years of age smell impairment was present in 13.5% of the U.S. population (Liu et al 2016). There are many other causes of anosmia, and this symptom should be considered within the whole picture of a patient’s presentation.

  • Stroke: a stroke, caused by hemorrhage or decreased blood flow to areas of your brain, may also affect your sense of smell if the stroke occurs in the geographic area that is tied to smell. If you are concerned that you or someone you know is having an acute stroke (remember, F.A.S.T.: Face droops, Arm weakness, Speech difficulty, Time is critical), please call 911 or go to an Emergency Department immediately.
  • Head injury/trauma: head trauma can cause smell impairment through direct damage to structures in the nose and/or sinuses, or through damage or bruising to the olfactory nerves.
  • Nasal or sinus disease (sinusitis, nasal polyps, allergies): these are the most common causes of anosmia and are caused by thickening of mucosa inside your nose.
  • Other viruses: “post-viral anosmia” is the cause of up to 40% of cases of anosmia (ENTUK). There are hundreds of different types of viruses that cause the common cold, or upper respiratory tract infections, which can temporarily damage some of the smell receptors in your nose.
  • Central nervous system abnormalities (Alzheimer’s disease, Parkinson disease, dementia, multiple sclerosis): there are many different inherited and acquired CNS abnormalities that may also result in a loss or change in your sense of smell.
  • Aging: as with many things, as we age, our sense of smell decreases, and this is normal. This is something, however, that happens over an extended period of time, so if you notice a very rapid change in your sense of smell (over hours to days), it may be something else.
  • Chemicals, toxins, metals, medications, and tobacco: other acutely or chronically inhaled, ingested or absorbed substances may all also contribute to changes in your sense of smell.

If I lose my sense of smell, should I be worried I have COVID-19?

If you lose your sense of smell and have other symptoms concerning for COVID-19 (fever, cough, shortness of breath), and you cannot identify another reasonable cause of your anosmia (like seasonal allergies), then your loss of smell may be another symptom of COVID-19. You should self-isolate at home, monitor your symptoms, and notify your primary care provider.

References:

  1. Liu G, Zong G, Doty RL, Sun Q. Prevalence and risk factors of taste and smell impairment in a nationwide representative sample of the US population: a cross-sectional study. BMJ Open. 2016 Nov 9;6(11):e013246. doi: 10.1136/bmjopen-2016-013246. PubMed PMID: 28157672; PubMed Central PMCID: PMC5129069.
  2. Loss of sense of smell as marker of COVID-19 infection. ENTUK. https://www.entuk.org/sites/default/files/files/Loss%20of%20sense%20of%20smell%20as%20marker%20of%20COVID.pdf

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