Poison Ivy, Oak and Sumac
These three plants are responsible for more cases of dermatitis than any other substances. When contact is made with any part of the plant a rash develops on the skin which is caused by a reaction to a chemical compound in the resin called urushiol that is found worldwide.  When the plant is burned, the smoke is an irritant that can cause a reaction in the respiratory tract. 

Red pimples extremely itchy, swelling, blisters, burning, fever and/or inflammation in the face or genitals area. The appearance of the symptoms can be between anywhere from a few hours to seven or ten days after contact with the plant. It can then spread rapidly during the next three days, especially with scratching. 

The areas most likely affected are hands, arms, face or legs. Scratching the rash can spread the inflammation to other parts of the body. Redness, swelling and itching usually begin to heal after the second day of the rash appearing.  Normally a person can be completely healed within fourteen days of first contact.