An NHS doctor has developed a breathing technique that he says can help coronavirus patients.
JK Rowling also claimed Dr Sarfaraz Munshi’s technique, which he devised while helping his mother, helped her when she was suffering from coronavirus symptoms.
Since the author shared his video on social media the new breathing exercise, which involves a controlled cough, has been viewed on YouTube more than 3 million times.
Despite its popularity, other doctors point out the exercise has not been subject to clinical tests.
"There are no clinical trials available to say whether controlled coughing helps the symptoms of people suffering from this coronavirus," Dr Roger Henderson wrote in the Spectator.
'We were panicking'
Ms Rowling said she was suffering with symptoms consistent with Covid-19 and Dr Munshi’s method helped her to feel better.
Dr Munshi, who works as an urgent care lead at Queen's Hospital in Romford, London, told BBC radio how he developed the technique.
“It’s very simple," he said. "I’m not someone who’s on social media so it really wasn’t for the mass public.
"But essentially my mother and father had Covid for the preceding 10 days, and Dad recovered quite well but unfortunately Mum started deteriorating.
“She had become so weak that she was laying on the couch for long periods.
"So the day before [making the video], my brother, who is also a doctor, and I were Facetiming and remotely assessing her oxygen levels, pulse and temperature.
"Mum’s oxygen levels weren’t picking up, so we did some simple respiratory exercises based on simple medical knowledge that she was getting mucus plugging and something called basal atelectasis.
“Initially, we were panicking but when oxygen levels came up we were reassured.
“The next day I spoke to my colleague Sue Elliot and she said: ‘Why don’t you make a quick video?’”
Not 'a cure or a miracle'
The video was initially sent to four people in her family WhatsApp group.
“The point here ... was that it’s not formal advice, but it’s a simple breathing technique that you can use that can help to oxygenate the lungs and open up the small airways.
“I just want to clarify, because some papers are quoting that this is in some way a cure or a miracle, that it’s far from it. There are many breathing techniques.”
