Dr Lai Yirong was packing up to go home at 8.20pm last Friday when she heard a worried mother rush into her clinic asking for help.
There was also a disturbing sound. "I heard a cough and it sounded high-pitched; it didn't sound normal," said Dr Lai, who runs a private clinic in United Square.
Striding out to the reception area, she saw four-year-old Braxton Ong in distress.
Braxton, who is allergic to peanuts, had eaten soba and oranges for dinner with his mother at a nearby eatery. Shortly after, his lips and eyes turned reddish, while his stomach began to bloat, said his father, Mr Steve Ong, 38, in a Facebook post on Saturday.
Dr Lai said: "He looked like he was struggling to breathe and I realised he had had a life-threatening allergic reaction that required immediate treatment."
There was not a moment to lose.
Dr Lai administered adrenaline and anti-allergy medication to the child to dilate his airways. She used a nebuliser - a device that turns medication into a breathable mist.
But she was concerned that Braxton appeared to be getting drowsy as he inhaled the drug.
AWARENESS IS CRUCIAL
People are not always aware that a reaction to an allergy can be life-threatening. Parents have to be aware of the food that they introduce to their children as they grow up, in case they are allergic to something.
DR LAI YIRONG
"Don't let him sleep!" she told his mother, who wanted to be known only as Mrs Ong. The doctor was afraid that if he fell asleep, he would lose the conscious effort to breathe.
The injection and nebuliser stabilised the boy's breathing, but a rash had erupted all over his body, causing him to scratch, said Mr Ong.
Mr Ong had been at an event but rushed to the clinic after his wife called him. "We were worried and fearful of losing him," he said.
Dr Lai stayed with the family in the clinic until she was sure that the boy's lungs were clearer, and he was then admitted to KK Women's and Children's Hospital (KKH).
Braxton was discharged from KKH yesterday and is "all good now" and active, said Mr Ong, who has another son, aged eight.
A test to determine the cause of the anaphylaxis, a serious allergic reaction, will be done in six weeks.
"I wanted to warn parents about allergic reactions and not to take them lightly," Mr Ong said of his Facebook post.
Dr Lai, who practises at Physicians Practice Family Medical Centre, said the incident has made her vigilant about alerting patients.
"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 something."
Allergic reactions, in which the body reacts to certain substances, are very common among children, she said, and can range from mild (a skin rash) to life-threatening (anaphylaxis). Common allergy-causing foods are peanuts and seafood. Bee stings can also cause anaphylaxis.
Mild allergic reactions can usually be treated with antihistamines to stop the symptoms, while a life-threatening one may require the use of an EpiPen - an adrenaline injection that can be self-injected - especially if there is no immediate medical help around, said Dr Lai.