HI, thanks for using healthcare magic These are anti histamines. It is the same anti histamine with just different names, she should not use them together since she would be using excess of the same drug. Anti histamines are appropriate for allergic reactions. Since the reaction is severe, her doctors may also want to consider the use of montelukast. She may also want to have allergy testing done to determine the source of her allergic reaction so that her exposure can be reduced or eliminated. I hope this helps