Rashes from poison ivy and poison oak can be extremely itchy. To stop the itch, try applying a cold compress of an ice pack wrapped in a towel for 15 to 20 minutes at a time. Calamine lotion, a topical antihistamine, hydrocortisone cream, or aloe vera gel may also help soothe the itch. Another thing you can try is a cool bath with baking soda or colloidal oatmeal. If the reaction is severe and home remedies do not bring relief, call your doctor. A course of steroids, such as prednisone, may be needed for the rash to heal.