My husband takes Hydroxyzine HCL (a strong antihistamine) and
uses Triamcinolone (an ointment) when the rash is bad. Both are prescriptions. He also
uses Eucerin body wash in the shower and Eucerin cream after the shower. When he had blisters on his back due to the rash, we put tea tree oil on them. I have also heard people say that pressing the itchy area up against a cold surface, stepping outside, standing in front of a fan, and putting ice on it helps.