We know that the common symptoms of coronavirus include a fever, cough, sore or scratchy throat and shortness of breath, however, one symptom that doesn't seem to be as commonly spoken about is olfactory hallucinations – or smelling odours that aren't actually there.
And it seems those with the virus who are experiencing these olfactory hallucinations are more often than not smelling smoke – more specifically: cigarette smoke.
A Facebook user with coronavirus took to the social media site to ask others who had the virus if they'd experienced anything similar, "Has anyone experienced 'olfactory hallucinations', i.e. smelling odours that aren't there? In my case, it is a constant burning smell, like cigarette smoke."
A number of other Facebook users agreed, revealing they too had experienced the strange symptom.
One commenter wrote, "Yes I could smell cigarettes and burning it drove me mad! I was convinced the kids were up to no good!"
"Yes. Cigarette smoke. Absolutely no reason or source for this," another user added.
"That was me! For my 2 weeks quarantine and maybe before it smelled like something burning in the kitchen. I noticed I got over it after that," someone else wrote.
Another said, "I keep thinking houses are on fire!" Someone else wrote, "I'm so glad to see others are experiencing this. I just thought my neighbours became heavy smokers all of a sudden."
Some were smelling different odours, one user wrote, "Chemicals. Smelled them again yesterday at day 131."
Another said, "I have smelled several different scents. The strongest was an ammonia smell."
"Chemical taste, fire smell," someone else added.
One user revealed a solution, "Try using a neti pot or saline spray daily, it really helps."
Australian Medical Association president Dr Tony Bartone spoke to Yahoo Lifestyle and revealed that olfactory hallucinations are indeed a symptom of coronavirus.
"Quite early on it's been made clear, it's actually now one of the criteria for testing, that COVID-19 – even before someone gets sick with other symptoms – can have an altered smell or taste. Or a loss of smell or taste.
"The three things we call them are – either you lose the smell, which is called anosmia, so you lose smell completely, or parosmia, which is basically an altered smell or taste or a thing called phantosmia, which is basically phantom smells. This is basically, in effect, smells that aren't there," he said.
Dr Bartone continued, "So you've got those three levels: loss, altered, or completely made up smells that aren't actually there. So we've known that that is actually something that can occur early on. It can persist and can actually be quite prolonged, although, hopefully the majority do recover, but some people are not recovering from their loss of smell."
He revealed that initially it was thought that the sense of smell was being lost simply due to blocked noses.
"But it's not. It's not due to just mucus blocking your nose. It's caused by direct effect on the nerves that you smell with, which are at the top of your nose. Coronavirus does something to damage them. So the nerves sit right at the top of your nose and they go straight into the brain.
"The virus is getting to these nerves where you do the smell and it's damaging them early. Doing something to them, hopefully temporarily in the majority of cases, but in many cases actually happened before people are getting the other symptoms and it's actually now become a criteria for testing."
"If you get a big change in your smell or taste, you should get a COVID test," Dr Bartone concluded.