Steroid prescription creams or ointments like high-potency triamcinolone 0.5% may be helpful during the first few days of a poison ivy rash on a small area, but have little effect once the fluid-filled blisters have appeared. Over-the-counter (OTC) products like hydrocortisone cream 1% are not usually strong enough for poison ivy. Your doctor may prescribe oral prednisone pills for a more severe rash.