Avoid scratching. Scratching may intensify the itching and increase the size of the hives. Take a long acting antihistamine such as Allegra (fexofenadine) or zyrtec to help decrease the hives and itching. See an allergist if they are persistent or recurrent.
Don't scratch. Scratching hives makes them worse. Cool showers will ease the itch. Taking over the counter Cetirizine (generic of zyrtec) 10 mg, 1 tab, at bedtime, every day, will control hives in the majority of cases. If the Cetirizine doesn't control the hives then you should consult an allergist.