The loss of smell that can accompany coronavirus is unique and different from that experienced by someone with a bad cold or flu, say European researchers who have studied the experiences of
patients. When Covid-19 patients have smell loss it tends to be sudden and severe. And they usually don't have a blocked, stuffy or runny nose - most people with coronavirus can still breathe freely. Another thing that sets them apart is their "true" loss of taste. It's not that their taste is somewhat impaired
because their sense of smell is out of action, say the researchers in the journal Rhinology. Coronavirus patients with loss of taste really cannot tell the difference between bitter or sweet. Experts suspect this is because the pandemic virus affects the nerve cells directly involved with smell and taste sensation. The main symptoms
of coronavirus are:
Anyone with these symptoms should self-isolate and arrange to have a swab test to check if they have the virus. Members of their household should isolate too to prevent possible spread.
Media caption,
Covid symptoms: What are they and how long should I self-isolate for?
Smell research
Lead investigator Prof Carl Philpott, from the University of East Anglia, carried out smell and taste tests on 30 volunteers: 10 with Covid-19, 10 with bad colds and 10 healthy people with no cold or flu symptoms.
Smell loss was much more profound in the Covid-19 patients. They were less able to identify smells, and they were not able to discern bitter or sweet tastes at all.
Prof Philpott, who works with the charity Fifth Sense, which was set up to help with people with smell and taste disorders, said: "There really do appear to be distinguishing features that set the coronavirus apart from other respiratory viruses.
"This is very exciting because it means that smell and taste tests could be used to discriminate between Covid-19 patients and people with a regular cold or flu."
He said people could do their own smell and taste tests at home using products like coffee, garlic, oranges or lemons and sugar.
He stressed that diagnostic throat and nose swab tests were still essential if someone thought they might have coronavirus.
The senses of smell and taste return within a few weeks in most people who recover from coronavirus, he added.
Prof Andrew Lane is an expert in nose and sinus problems at Johns Hopkins University in the US.
He and his team have been studying tissue samples from the back of the nose to understand how coronavirus might cause loss of smell and have published the findings in the European Respiratory Journal.
They identified extremely high levels of an enzyme which were present only in the area of the nose responsible for smelling.
This enzyme, called ACE-2 (angiotensin converting enzyme II), is thought to be the "entry point" that allows coronavirus to get into the cells of the body and cause an infection.
The nose is one of the places where Sars-CoV-2, the virus that causes Covid-19, enters the body.
Prof Lane said: "We are now doing more experiments in the lab to see whether the virus is indeed using these cells to access and infect the body.
"If that's the case, we may be able to tackle the infection with antiviral therapies delivered directly through the nose."
Overview
What is anosmia?
Anosmia is the loss of sense of smell. This condition affects your ability to detect odors.
What is the difference between ageusia and anosmia?
While anosmia refers to a total loss of smell, ageusia refers to a complete loss of taste. These two conditions sometimes occur together because sense of smell and sense of taste are closely related.
Are there other smell disorders?
Yes. In addition to anosmia, people can also develop phantosmia (smelling things that aren’t there), parosmia (a distorted sense of smell) and hyposmia (a reduced sense of smell).
Who does anosmia affect?
Temporary anosmia can affect people of all ages. But a long-lasting loss of sense of smell is more common among adults over the age of 50. In rare cases, people have congenital anosmia. In other words, they were born with the condition. Congenital anosmia affects roughly one in 10,000 people.
How common is anosmia?
Anosmia is a common side effect of many conditions, including colds, sinus infections and allergies. Most of the time, symptoms are temporary and resolve themselves in a short amount of time. Anosmia is also a common symptom of COVID-19.
Is anosmia dangerous?
While anosmia itself usually isn’t dangerous, it can be related to many concerning health issues. Additionally, it can reduce your ability to detect the smell of smoke, gas leaks or spoiled food. As a result, people with anosmia should take extra steps to ensure that their environment is safe. Change the batteries in your smoke detectors frequently and read food expiration dates carefully.
Diagnosis and Tests
How is anosmia diagnosed?
Anosmia is usually diagnosed by an ear, nose and throat specialist (ENT). They’ll ask you about your symptoms, examine your nose and run tests to determine the extent of your loss of smell. In some cases, a CT (computed tomography) scan may be necessary to help your provider see what’s going on inside your body.
Management and Treatment
How is anosmia treated?
In most cases, treating the underlying condition can help restore your sense of smell. For example, if you have sinusitis, then antibiotics can help clear up the infection. If certain medications are affecting your sense of smell, then switching meds may help ease your anosmia symptoms. If you have nasal polyps or another type of blockage, surgery may be necessary. Your healthcare provider can help determine any underlying conditions and recommend appropriate treatment.
Can anosmia be cured?
It depends on the type of anosmia you have. There is currently no known cure for congenital anosmia. In most cases, however, anosmia goes away on its own. Generally, once the underlying problem is treated, your sense of smell is restored.
Prevention
Can anosmia be prevented?
Because anosmia is a symptom of many health-related conditions, it can’t always be prevented. However, there are certain things you can do to reduce your risk:
- Avoid toxic chemicals and environments.
- Don’t smoke.
- Wear protective gear when playing contact sports, since anosmia can be caused by brain injuries.
Can anosmia be permanent following a COVID-19 infection?
Loss of sense of smell is a common side effect of COVID-19. However, current research has determined that coronavirus may cause smell dysfunction, but it doesn’t cause permanent anosmia.
Outlook / Prognosis
What can I expect if I have anosmia?
If you’ve been diagnosed with anosmia, your healthcare provider can help manage your symptoms until your sense of smell is restored.
How long can anosmia last?
It depends on the underlying cause of your anosmia. Most of the time, your sense of smell returns once treatment is complete.
How long is anosmia after COVID?
People who have anosmia as a COVID-19 side effect usually regain their sense of smell in approximately two to three weeks. This is an estimate; recovery times can vary.
Living With
When should I see my healthcare provider?
Anosmia related to colds, flus and infections usually goes away within a few days. If you have lingering anosmia, schedule a consultation with your healthcare provider.
What questions should I ask my healthcare provider?
If you have anosmia, understanding your condition can put your mind at ease and help you make decisions regarding treatment. Here are a few questions you may want to ask your provider:
- Is my loss of smell due to a cold, flu or infection?
- Do I have an underlying condition that needs to be treated?
- Could any of my medications be causing anosmia?
- Are there other things I can do to restore my sense of smell?
Frequently Asked Questions
Can you taste without smell?
Smell and taste are closely related. Your tongue can detect sweet, sour, salty and bitter tastes. But without your sense of smell, you wouldn’t be able to detect delicate, subtle flavors.
A note from Cleveland Clinic
Most of the time, losing your sense of smell isn’t serious. But there are instances in which anosmia indicates other, more serious health conditions. If you develop sudden or prolonged loss of smell, contact your healthcare provider. They can find the underlying cause of your anosmia and recommend treatments to ease your symptoms.