<<Disclaimer: Verify this information before applying it to your situation.>> I cannot tolerate Lactaid milk and couldn't figure out why. (Same symptoms as though there WERE lactose in it!) Someone told me that when Lactaid first came out, it had a warning on it for people who are allergic to penicillin (as did Beano, when it first came out). The enzymes in both are developed on a mold similar to penicillin, apparently. Both products stopped putting the warning on quite some time ago. I am allergic to penicillin, and I think this person solved the mystery for me! My son can use Lactaid with no ill effects, but he is not allergic to any medications (yet!) So, if any of you out there react to Lactaid and assumed it was gluten, there may be another reason (since it IS gluten free!) Anne Washburn