It can be used to treat gastric reflux (a condition in which the acid stomach contents flow upwards into the food pipe) and flatulence caused by gastric reflux. Gaviscon infant sachets are an oral powder which is suitable for children ages 1 to 2. It contains two main ingredients, sodium alginate and magnesium alginate which form a gel in the stomach when they come in contact with the stomach acid. This causes stomach contents to thicken and prevents reflux.