People can have allergies/ or an intolerence to beer ingredients, someone could have an allergy to hops, or yeast, or the gluten in the grain, someone could be lactose in tolerant and have gastric issues from a sweet stout.
There's going to be two kinds of reactions, things like hives and respiratory, like a peanut allergy, and someone can get cramps and the runs-which is more like a lactose issue.
But they are going to be pretty immediate, the hives and resp are going to happen within minutes, if not sooner, and the GI would still more than likely happen within an hour maybe 2.
True food allergies are your body's immune (IgE) response to food proteins, and only food proteins. The most common are milk, egg, peanuts, tree nuts and shellfish. Food intolerance (Gluten/Lactose) causes strictly GI issues, although food allergens will cause vomiting, but along with the other symptoms, such as hives, swelling, etc.
And the thing is, if someone is allergic to most of the beer ingredients then a) then they will be allergic to all beers, even commercial, unless it is yeast, then it would be with SOME commercial beers, that are unfiltered. BUT they would also then be allergic to bread as well. Since the same yeast is used in baking.
The hardest one to figure would be a hop allergy, since except for beer, hops don't really appear in other things. BUT then also, the person would be allergic to other beers as well.
When people post asking about this, I usually caution them to look to other things in their environment rather than homebrew, since those allergies are rare and manifest with similar ingredients (like bread) or happen with commercial beers as well.
There's no difference really between Homebrew and Commercial brew EXCEPT for the fact that it's unpasteurized (except the commercial ones that aren't pasteurized) and a lot more yeast (except for those that are bottle conditioned) so she'd really more than likely have it happen with commercial beers as well.
Rather than ask a bunch of non doctors though, if she really has an issue she should consult an allergist, maybe even taking a bottle of HB with her.