Jon Bon Jovi was shocked to discover his daughter was taking drugs.

Stephanie Bongiovi, 19, was rushed to hospital after being found unresponsive in her dorm room at Hamilton College in Kirkland, New York last month and the rocker admitted he was devastated at the teenager's ''sudden and steep decline'' when drugs including heroin and marijuana were reportedly found in her room.

He said: ''I didn't have any sisters. We bring home this girl the first day. Now what? Where's the manual? There was no manual. So you bring her up the best you can, you surround her with hugs and kisses and know that she may eventually fall down... I'm shocked as much as the next parent with this situation and had no idea. But then you surround them with best help and love and move on, and that's where we're at with it. Steph is a great kid... Cool school, Hamilton College up in Clinton, New York.

''Everything about it is idyllic. She was doing great. Then a sudden and steep decline.''

While Jon and his wife Dorothea believe Stephanie will be fine, the 50-year-old rocker admitted the incident has left him shaken.

He said: ''Hopefully, we caught it when we did and that's the end of it. But who knew? I've got three more (children) to come (grow up).''