I just want to make sure I understand–
Is it a juice or a tea? If it’s just squeezed lemon/grated ginger steeped in water, that’s one thing. If it’s a prepackaged/etc juice packed with sugar, it’s going to massively spike your insulin in the AM. If you drink it in the morning it will definitely break your fast (the sugar version) if you take it before 2:30.
As far as whether or not it will upset your stomach, the juice might. Many people don’t do well with sugar. The tea would actually probably help settle your stomach.