What is the best colon cleanse, and are they safe?

Hello, I have been wanting to try a colon cleanse. I need someone who knows or who has used one to tell me a few things:
is it ok to use one at my age of 15,
will it be painful,
will I be spending the majority of my days on the toilet,
are they safe,
and which one would you personally recommend?
I don’t want to get in over my head here.