A product called Ivy Block provides an effective barrier against urushiol if you are going hiking or doing yard work. There is no approved safe oral desensitizing medicine. Clothes that might be contaminated with the allergic resin should be washed with soap and water. If the rash is weeping, then cool wet compresses applied for 15 minutes several times a day will lead to rapid drying and relief. Shake lotions like Calamine, Caladryl, and Tech-nu provide relief in mild cases.
More intense cases require prescription steroid medication.
Steroid creams will reduce itching and shorten the course if the rash is limited. Oral steroids work within 48 hrs to reduce the spread and intensity of the rash.