Hi, I can understand your concern for mouth dryness related to poison ivy on face. After reading your query the closest possibility of your problem appears to be allergic dermatitis . This is a condition caused by bursting of allergy producing cells known as mast cells . As the chemical inside them is released causes the kind of rash which you mentioned. Kindly follow the suggestions below: -Apply fluticasone cream 2 times a day. For dryness you can apply a moisturzing cream alternatively. -You can do cold water compresses to reduce the intensity of itching. -Do not scratch or rub the skin as it can lead to further aggravation. -you can give her oral anti histamine like loratadine or levocetrizine under medical advise. Despite above measures if the problem is not getting better then it is better to consult a dermatologist for best guidance. Take care.