My son, who does not have CF got this awful rash/hive/? bug bites all over his legs yesterday. It looked pretty awful, itchy and red, not sure where he got it. But I immediately gave him a good dose of benadryl and rubbed on hydrocortisone cream. It helped sooo much. Our CF doc and ped always tell us not to give Maggie benadryl because it will dry her out. They've drilled this into me, So what'll give for allergic reactions and such. She's going to camp in a couple weeks so I figure it's possible she'll get bit by something. What happened to my son just got me thinking. Maggie has had benadryl once when she was getting Vanco(red man syndrome) and it did seem to dry her out.