My dog reacted to liver vitamins. Is she having an allergic reaction?

Dogs can have allergic reactions to almost anything, but I think it would be fairly rare to have a drug eruption from liver vitamins. Allergic reactions typically cause hives and/or facial swelling, while a drug eruption causes skin lesions that are typically not itchy. It might help to know exactly what is in the vitamins since some medications are more likely than others to cause a reaction. Of course there are many other things that can cause skin lesions to the liver vitamins might not be to blame.