Ivarest is a cream that relieves the itching and dries out the boils caused by poison ivy, oak, and sumac. Poison ivy, oak, and sumac all cause allergic reactions in most people. Itchy painful boils break out on the skin, and they can last for weeks. In severe cases, it can put some people in the hospital, especially if it reaches the throat and lungs.
As someone who once got intimately familiar with a patch of poison ivy, I can say that Ivarest saved me from several unbearably itchy weeks. It is not magic; it will not stop the itching completely; it will not cure the allergic reaction; but it did let me sleep at night without tearing my skin off from itching.
Ivarest only relieves the symptoms of the reaction, so use it with diphenhydramine (Benadryl) pills for added benefit.