The Poison Ivy is the brokenness that we all have, deep down in our souls.
The scalding shower and the scratching are the ways we try to cover over our brokenness or numb the pain... maybe it's a codependent relationship, an addiction, escaping to video games or TV or comfort foods... Feels REALLY good, but does more harm than good...
The "trying not to scratch" is the way we try to help ourselves by "controlling" our lives and fixing our problems.
Jesus is the Tecnu; the Solution; the Way, the Truth and the Life; the One who satisfies our deepest longings; the One who heals us.