Wash the area immediately with strong soap. Application of an antihistamine cream or steroid cream may help with the itching or taking an antihistamine, especially Benadryl may relieve some of the itching. See Poison Control centers for telephone numbers and addresses.
Fatalities are very uncommon.
At worst the individual will be very uncomfortable for a while. A secondary skin infection may develop if the exposed areas are not kept clean. This is a typical appearance of a poison ivy rash. The person then spreads the toxins to other areas of the body by scratching. Poison oak rash on the arm.