Try 'smell training' while recovering from Covid-19: New study

London - The research against the use of corticosteroids is contrary to conventional prescription to regain smell.

By Prasun Sonwalkar

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Published: Sat 24 Apr 2021, 6:18 PM

Instead of using drugs such as corticosteroids to regain the sense of smell while recovering from Covid-19, a new study by an international team of researchers suggests a period of ‘smell training’ as a free and simple way to retrain the brain to recognise smells.

Losing the sense of smell and taste is recognised as one of the key symptoms of Covid-19, with many losing smell on a long-term basis. Usually, corticosteroids are prescribed to help regain smell, but the study published in the journal International Forum of Allergy & Rhinology does not recommend using them.


Instead, the researchers recommend ‘smell training’, which involves sniffing at least four different odours twice a day for several months.

Smell loss expert Carl Philpott from the University of East Anglia’s (UEA) Norwich Medical School notes that the rise in smell loss caused by Covid-19 has created an unprecedented worldwide demand for treatment.


Around one in five people who experience smell loss as a result of Covid-19 report that their sense of smell has not returned to normal eight weeks after falling ill.

He said: “Corticosteroids are a class of drug that lowers inflammation in the body. Doctors often prescribe them to help treat conditions such as asthma, and they have been considered as a therapeutic option for smell loss caused by Covid-19”.

“But they have well-known potential side effects including fluid retention, high blood pressure, and problems with mood swings and behaviour,” he added.

The team carried out a systematic evidence-based review to see whether corticosteroids could help people regain their sense of smell.

Philpott said: “We found that there is very little evidence that corticosteroids will help with smell loss. And because they have well known potential adverse side effects, our advice is that they should not be prescribed as a treatment for post-viral smell loss.

“Luckily, most people who experience smell loss as a result of Covid-19 will regain their sense of smell spontaneously. Research shows that 90 per cent of people will have fully recovered their sense of smell after six months”.

“But we do know that smell training could be helpful. This involves sniffing at least four different odours twice a day every day for several months. It has emerged as a cheap, simple and side-effect free treatment option for various causes of smell loss, including Covid-19, he added.

According to him, smell training aims to help recovery based on neuroplasticity: the brain’s ability to reorganise itself to compensate for a change or injury.

The research was led by researchers at the Cliniques Universitaires Saint-Luc in Brussels (Belgium) in collaboration with the Univeristé Catholique de Louvain, Brussels (Belgium), the UEA (the United Kingdom), Biruni University, Istanbul (Turkey), Aarhus University (Denmark), Université du Québec à Trois-Rivières (Canada), Geneve University Hospitals (Switzerland), Harvard University (USA), Aristotle University, Thessaloniki (Greece), University of Insubria (Italy), University of Vienna (Austria), the University of Chicago (USA) and the University of Colorado (USA).

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