What if someone is allergic to an element of the Lord’s Supper?
How do people with severe allergies take communion? If someone has a severe allergy to gluten or flour or something else that is needed to make the bread, what are they supposed to do? Can they bring their own tapioca wafer or are they merely doomed to Hell? What about the fruit of the vine? If someone has a grape allergy are they simply lost forever? There are people out there that have allergies that are so severe that a bit of communion bread or a sip of grape juice can have terrible consequences. What are they to do?
Regarding gluten-free, see: What do you think about offering wafers with the communion bread?
In regards to grape juice, the question would be what a person is allergic to. It can be an allergy to the pesticides used on grapes, the yeast on grapes, the mold sometimes found on grapes, or the sulfites added to preserve grapes. Some people are allergic to a particular type of grape, so while they can't drink red grape juice, they aren't bothered by white grape juice. So often alternatives can be found.
A rule doesn't become invalid because you believe there might be an exception. Such is never the case. And since it doesn't apply to your situation, it isn't a concern for you personally.