Lipton ice tea mix is acidic. The “tea” in Lipton ice tea mix is somewhat bitter tasting, so the product contains a lot of sugar crystals to take away that bitter taste. The product’s acidity comes from both the “tea” and the sweetener mixed with the tea. When the ice tea is made, ice water is also acidic while boiling water is alkaline. Thus in ice tea, the acidity comes from the “tea”, the sweetener and the ice water.
This triple acidity causes heartburn.