SINGAPORE - It was around 8.20pm on Friday night (Oct 6) when Dr Lai Yirong was packing up to go home that she heard a worried mother rush into her clinic to get assistance for her son.

"I heard him cough and it sounded high-pitched; it didn't sound normal," recalled Dr Lai, who runs a private clinic at United Square.

"He looked like he was struggling to breathe and I realised he had an allergic reaction that required prompt treatment."

She immediately administered adrenaline and anti-allergy medication to four-year-old Braxton Ong to dilate his airways. This was done through a nebuliser - a device that turns medication into a breathable mist.

Braxton started breathing better, but he had a rash on his entire body and kept scratching, said his father, Mr Steve Ong. He had been at an event but rushed down to the clinic after his wife informed him of the incident.

"We were worried and fearful of losing him," said Mr Ong, 38, a manager at Samsung Asia.

Dr Lai remained with Braxton's parents in the clinic until she was sure that his lungs were clearer, and he was admitted to KK Women's and Children's Hospital (KKH) more than half an hour later.

Braxton was discharged from KKH today (Oct 8) and is "all good now" and "very active", said Mr Ong, who has another son, aged eight.

A test to determine the cause of the severe allergic reaction, called anaphylaxis, will be done in six weeks' time, he added.

Braxton, who is allergic to peanuts, had eaten soba noodles and oranges for dinner and shortly after, his lips and eyes turned reddish while his stomach began to bloat, recounted Mr Ong in a Facebook post, which has since gone viral.

"I wanted to warn parents about allergic reactions and not take them lightly," he said.

For Dr Lai, who practises at Physicians Practice Family Medical Centre, the incident has made her more vigilant about educating her patients about severe allergic reactions.

"People are not always aware that a reaction to an allergy can be life-threatening," she said. "Parents have to be aware of the food that they introduce to their children as they grow up, in case they are allergic to one of the food items."