My daugther is having a reaction and is itching?

To what?: You don't mention what you think she is having a reaction to. Is she on a medication, have bug bites, ate something new? If the reaction is just the itchy rash, oral Diphenhydramine (benadryl) will help settle down the reaction and relieve the itch. If she is having any facial swelling, tongue or throat swelling or difficulty breathing, this is medical emergency and she needs to go to er.

"reaction": If you're unable to describe what the "reaction" is, it may be safer to have her looked at in-person by a doctor. Shortness of breath, wheezing, facial and throat swelling are some signs and symptoms which would require immediate medical attention.