How do you prune a century plant?

I attempted to prune this plant with a chain saw and WHAT A MISTAKE. Every where my skin was in contact with the sap or juice from inside I was covered in an instant burning sensation. A day later I felt flu like. The same day later I had very bad red bumps all over my legs and stomach or anywhere it got on me. And the third day they turned into white blisters. Very painful and very itchy. Do not attempt to cut them and if you have children or animals I would pay someone to get rid of them.