Covid Is Distorting People's Sense Of Smell In Really Unpleasant Ways

We all know loss of sense of smell or taste is one of the key symptoms of Covid-19 , but less spoken about is the distorted sense of smell – and subsequently, taste – that some people are left with (known as parosmia).

Professor Nirmal Kumar, an ear, nose and throat (ENT) consultant and president of ENT UK, says he used to come across the issue “once in a blue moon” before Covid-19, but now he’s seeing five or six patients every week with a persistent distorted sense of smell.

Often, the issue occurs after someone has lost their sense of smell completely and begin to recover, noticing their smell and/or taste is altered – and not in a very nice way.

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People impacted will often describe foods they’d previously enjoyed as smelling disgusting, foul, acrid, fishy, unpleasant, or similar to burning or charred flesh.

Chrissi Kelly, founder of AbScent.org,  a charity supporting people with smell loss, is in regular contact with people whose smell is impacted post-Covid and says while some have recovered, others are still waiting for their senses to return to normal nine months after falling sick.

“There’s nothing unusual in parosmia taking over a year to right itself,” says Kelly, who temporarily lost her sense of smell following a virus in 2012, “and it may not ever get back 100% to what it was.”

A study from Italy of 202 mildly symptomatic Covid-19 patients found that after four weeks from the onset of illness, 55 patients (48.7%) reported complete resolution of smell or taste impairment, and 46 (40.7%) reported an improvement in the severity. A further 12 (10.6%) reported the symptom was unchanged or worse.

Discussing the impact of this issue on people’s lives, Kelly says there is a “spectrum of distress”. Some people notice their food tastes funny but otherwise they’re ok, while others are vomiting excessively and in some cases losing a lot of weight.

There are common trigger foods like coffee, meat (especially if it’s been fried or roasted), onions, eggs, garlic, peanuts and cucumber that people can no longer stand, she adds. Hygiene products, like toothpaste, can also become a problem.

Other people have found that while the smell of food becomes disgusting, the smell of poo becomes almost palatable, says Kelly. “Everyone knows poo is a disgusting smell. For people with parosmia, suddenly food smells disgusting and poo starts to smell like food – it’s a crazy thing for people to get their head around.” 

Why does it happen? 

Experts have believed for a while now  that the virus enters the nasal tissues through an enzyme called the angiotensin converting enzyme II (ACE-2) receptor (which is basically a Covid magnet, and there’s lots of it in the nose) – and then causes damage to the olfactory receptor nerve endings or supporting olfactory cells within the nose. This results in a change to a person’s sense of smell.

A team of ENT specialists and researchers from University College London are currently examining biopsies of damaged olfactory cells to see how the virus impacts them – and determine whether something can be done to help restore people’s senses.

It’s not yet known whether the damage is permanent. Researchers believe potential regeneration of these cells could take at least 18 months.

Consultant rhinologist Peter Andrews, who is involved in this research, said: “Olfaction (the cells which enable us to smell) is the only part of the central nervous system which can regenerate. They usually regenerate every six weeks in the nose to replace receptors that have been damaged by pollution and toxic fumes. However, frustratingly following a viral attack such as flu or Covid-19 this capacity to regenerate is sometimes lost.”

So that explains the loss of smell, but what about parosmia specifically? Dr Afroze Khan, a consultant ENT surgeon at Hampshire Hospitals NHS Trust, tells HuffPost UK that while we don’t know why parosmia is taking place, there’s a theory (based on previous studies) that there’s an increase in “immature neurons or cells” in the part of the nose responsible for a person’s sense of smell.

These cell have been destroyed by the virus that causes Covid-19. However in this part of the body, cells can regrow. The cells’ ‘immaturity’ could explain why people’s sense of smell becomes, for want of a better word, messed up. Once these cells are matured, the hope is that the sense of smell return to normal.