Poison sumac can be treated effectively with calamine lotion, according to WebMD. The itchiness and burning can be soothed by applying cold ice and pressure to the affected location for 15 to 20 minutes at a time. Antihistamines are also shown to help with symptoms.
Those that suspect they have come in contact with poison sumac should wash the exposed area with soap and water to help prevent a rash, suggests WebMD. Clothing that comes in contact with these plants should be laundered, as the oil that causes skin irritation may remain on the fabric for a period of time. Individuals with severe allergic reactions or complications from extreme exposure should seek medical attention.
Known as urushiol, the toxic oil can spread through light contact, whether with the plant, its roots or something the oil has transferred onto, states WebMD. The oil remains toxic and dangerous even when the plant is dead. However, unless the oil remains on the skin, the rash cannot be transferred by touching someone's blister.
Symptoms include itching, hives, blisters and red streaks, according to WebMD. The symptoms are triggered by an allergic reaction to the oil that causes the body to treat uroshiol as a harmful substance. Repeated exposure can worsen reactions. More serious symptoms are swelling, widespread blisters and trouble breathing.
The rash first appears anywhere from a day to a week after initial contact, reports WebMD. It can last between 10 days to six weeks.