Hmmm i'm not sure, I don't know of the sugar content?
In the past, if I had run out of rennie etc, I would take a glass of water with a teaspoon of bicarbonate of soda in it. It works a treat (although it tastes like sh*te), my gran recomended it years ago and it works. But I don't know if thats allowed either?
Heartburn is horrible, and I hope you feel better *hugs*