Poison Ivy, Oak, and Sumac
Definition
Poison ivy, oak, and sumac are allergic skin rashes (or Rhus dermatitis) caused by the plants of the same name. All three plants secrete a potent, irritating oil known as urushiol that causes blistering and intense itching once it penetrates the skin.
Description
The allergic rash of poison ivy, oak, and sumac is characterized by red, weeping blisters and severe itching. The rash usually appears within one to two days of initial contact with the plant oil, although it may take longer to appear in areas where the skin is thicker, and lasts from one to three weeks (longer in severe cases). It starts as itchy, inflamed red patches...
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