People in certain jobs or with outdoor hobbies have an increased risk for contact with poison ivy, oak, or sumac and the resulting rash (allergic contact dermatitis). These people include:

• Landscapers.
• Forest firefighters and forestry workers.
• Electrical linemen.
• Those who install fences.
• Maintenance workers in parks, gardens, and nurseries.
• Hikers, campers, rafters, kayakers, and fishermen.

Your risk of reacting to poison ivy, oak, or sumac and the severity of your allergic reaction depend mainly on your age and on the extent of the first contact or first few contacts with the plant. Other influences include physical activity and immune system function.³ Some studies show that how allergic you are to the plants may be inherited.³