There are a number of variables, but I expect like most things it will bother some people quite a bit and be just fine for plenty of other people.There generally are no absolutes in IBS (X is bad for everyone Y is safe for everyone, but there are some things that are often bad for a goodly percentage of us).Is the Lemonade commercially prepared?If so check the label to see if it has high-fructose corn syrup. That can be a major problem for some people.Others may not do well with large amounts of sucrose eitherStill others will do badly if it is artificially sweetened.If most soft drinks bother you and it has high fructose corn syrup I would avoid it.If most diet drinks bother you then avoid the artificially sweetened kind.If anything sweet bothers you than lemonade may not be for you because it takes a goodly amount of sugar to make it drinkable.If any other acidic foods bother you (tomatoes, other citrus) then it may not be for you.K.