I would recommend using Tecnu Original Cleanser as it does not contain alcohol. See label info here. However, please note that Tecnu is a strong detergent so if your friend is allergic to alcohol, she may also be sensitive to other ingredients.

After washing with Tecnu, which will remove the plant's rash causing oil, your friend may need an anti-itch medication.  Calagel also does not contain alcohol - see label here or she can use whatever anti-itch medication she has at home that is effective for her.