For years, eating even a smidgen of peanut butter would make Tng Shih Kai feel nauseated, giddy and break out in rashes.
Now - three months after completing a programme to increase his tolerance to the food - he can eat more than 10 peanuts at a go without triggering an allergic reaction.
It sounds like a small thing, but it has made a big difference to the 13- year-old and his family.
"We had to diligently check the menu before we ordered food (at restaurants), and at supermarkets, we would check all the labels," recalled his father Tng Yan Hui, 45.
In 2015, the National University Hospital (NUH) started its food oral immunotherapy programme, focusing only on peanuts.
No medication is involved. Instead, a child is fed minuscule amounts of the food that he is allergic to, with the dose gradually increased until he can safely stomach small amounts.
Cow's milk was added last year, and there are plans to expand it to include other common allergens such as eggs or tree nuts.
Dr Soh Jian Yi, who is from the hospital's division of paediatric allergy, immunology and rheumatology, said the standard advice for parents is to keep their children away from foods that trigger allergies.
"It is easy for us as physicians to say that," he said. "But for the parents and the child, it translates into a lot of worry and work over the days and months."
Around 20 children with persistent food allergies lasting past age five, when many children have outgrown them, have been enrolled in the scheme so far.
Though allergies are rarely studied here, it is estimated that peanut allergies affect up to 0.5 per cent of children of school-going age.
The whole process typically takes between six and 10 months, after which children will need to keep eating some of this food in small doses, at least twice a week indefinitely, for it to remain effective.
NUH said the entire course of treatment costs between $2,500 and $4,500 for subsidised patients, and that any child over age five with these allergies can enrol. It hopes to expand it to adults in the future.
Dr Soh said parents should not attempt this treatment regimen on their own. It is difficult to accurately measure food portions of less than a milligram, and the child may have a severe adverse reaction.
Since completing the treatment, Shih Kai and his parents no longer worry about trace amounts of peanuts in his food.
Even better, he can now indulge in something he has wanted to eat for a long time - satay sauce.
Shih Kai said: "I would see my friends eat it, and it smelled good. I would feel envious."